Arizona Parkway Intersection/Interchange Operational Analysis and Design Concepts Study

Transcription

1 Arizona Parkway /Interchange Operational Analysis and Design Concepts Study Final Report August 2009 Prepared for: Maricopa County Department of Transportation 2901 West Durango Street Phoenix, Arizona Prepared by: 410 North 44 th Street, Suite 460 Phoenix, Arizona : 8710 North Thornydale Road, Suite 140 Tucson, Arizona 85742

2 Arizona Parkway /Interchange Operational Analysis and Design Concepts Study Final Report August 2009 Prepared for: Maricopa County Department of Transportation 2901 West Durango Street Phoenix, Arizona Prepared by: Wilson & Company, Engineers & Architects 410 North 44 th Street, Suite 460 Phoenix, Arizona : Morrison-Maierle, Inc North Thornydale Road, Suite 140 Tucson, Arizona 85742

3 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study TABLE OF CONTENTS 1 INTRODUCTION BACKGROUND PURPOSE PROJECT STUDY AREA ARIZONA PARKWAY NETWORK APPLICABLE NETWORK MODELS INTERSECTIONS IDENTIFIED FOR EVALUATION NETWORK VOLUMES NETWORK LANE RECOMMENDATIONS INTERSECTION ENTERING VOLUMES ARIZONA PARKWAY NETWORK ANALYSIS INTERSECTION ENTERING VOLUME CAPACITY THRESHOLDS Capacity Methodology Estimating Peak-Hour Volumes Identifying Volume Thresholds ENTERING-VOLUME THRESHOLDS FOR INTERCHANGE/GRADE SEPARATIONS At-/ Threshold Analysis Threshold Capacity GRADE-SEPARATED INTERCHANGE CONCEPT DESIGNS Single-Point Urban Interchange (SPUI) Standard Diamond Interchange Diverging Diamond Interchange (DDI) GRADE-SEPARATED INTERCHANGE OPERATIONS ANALYSIS PARKWAY GRADE-SEPARATED INTERCHANGE (PGSI) THE PARKWAY GRADE-SEPARATED INTERCHANGE CONCEPT Design Description Principal Characteristics of the PGSI Operational Analysis PEDESTRIAN ACCESS AND SAFETY MAINLINE ACCESS MANAGEMENT COST OPINION DETAILED TRAFFIC OPERATIONS ANALYSIS OF THE PARKWAY GRADE-SEPARATED INTERCHANGE ANALYSIS METHOD ANALYSIS RESULTS PRELIMINARY CAPACITY ESTIMATE FOR THE PGSI DETAILED ANALYSIS CONCLUSIONS FINDINGS AND RECOMMENDATIONS SEGMENT CAPACITIES AND REQUIRED NUMBER OF LANES FOR THE ARIZONA PARKWAY NETWORK AT-GRADE INTERSECTIONS GRADE-SEPARATED INTERCHANGES GRADE SEPARATION RIGHT-OF-WAY PRESERVATION RECOMMENDATIONS Page i

4 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study LIST OF FIGURES FIGURE 1.1 HASSAYAMPA & HIDDEN VALLEY FRAMEWORK STUDIES PLANNING AREAS FIGURE 1.2 ARIZONA PARKWAY INTERCHANGE DESIGN STUDY AREA FIGURE 2.1 PARKWAY-TO-PARKWAY INTERSECTIONS IN THE STUDY AREA FIGURE 2.2 STUDY AREA BUILDOUT PARKWAY NETWORK SEGMENT VOLUMES FIGURE 2.3 RECOMMENDED NUMBER OF LANES FOR BUILDOUT PARKWAY NETWORK FIGURE 3.1 INTERSECTION MAXIMUM THRESHOLD VOLUME ANALYSIS METHODOLOGY FIGURE 3.2 MAXIMUM DAILY ENTERING VOLUME THRESHOLDS BY AT-GRADE INTERSECTION TYPE FIGURE 3.3 MAXIMUM DAILY ENTERING VOLUME THRESHOLD BY INTERCHANGE TYPE FIGURE 3.4 STANDARD DIAMOND INTERCHANGE PARKWAY CONCEPT DESIGN FIGURE 3.5 SINGLE POINT URBAN INTERCHANGE PARKWAY CONCEPT DESIGN FIGURE 3.6 DIVERGING DIAMOND INTERCHANGE PARKWAY CONCEPT DESIGN FIGURE 4.1 PARKWAY GRADE-SEPARATED INTERCHANGE CONCEPT DESIGN FIGURE 4.2 MAXIMUM DAILY ENTERING VOLUME THRESHOLD BY INTERCHANGE TYPE INCLUDING THE PGSI FIGURE 4.3 PARKWAY GRADE-SEPARATED INTERCHANGE CONCEPT DESIGN WITH HIGH VOLUME DIRECT CONNECTOR/FLYOVER RAMP: INTERSECTION #23 SUN VALLEY PARKWAY/BELL ROAD AT JACKRABBIT TRAIL PARKWAY FIGURE 4.4 PARKWAY GRADE-SEPARATED INTERCHANGE CONCEPT DESIGN WITH HIGH VOLUME DIRECT CONNECTOR/FLYOVER RAMP: INTERSECTION #61 HIDDEN WATERS PARKWAY AT WATERMELON PARKWAY FIGURE 4.5 TYPICAL PGSI PEDESTRIAN MOVEMENT PATTERN FIGURE 4.6 ACCESS MANAGEMENT CONCEPT FOR PGSI AND ARIZONA PARKWAY (6-LANE TO 8-LANE) FIGURE 5.1 SIMTRAFFIC REPRESENTATION OF PGSI OPERATIONS FIGURE 5.2 COMPARISON OF DELAY PER VEHICLE BY MOVEMENT: PGSI V. SPUI FIGURE 5.3 COMPARISON OF AGGREGATE DELAY PER VEHICLE BY MOVEMENT FIGURE 5.4 COMPARISON OF AGGREGATE STOPS PER VEHICLE BY MOVEMENT FIGURE 5.5 PGSI DELAY PER VEHICLE AND TRAFFIC VOLUME BY MOVEMENT FOR ESTIMATING INTERCHANGE CAPACITY 5-5 FIGURE 6.1 ARIZONA PARKWAY NETWORK RECOMMENDATIONS FIGURE 6.2 PARKWAY GRADE-SEPARATED INTERCHANGE LIST OF TABLES TABLE 2.1 ARIZONA PARKWAY LEVEL OF SERVICE THRESHOLDS TABLE 2.2 SEGMENT ANALYSIS FOR PARKWAY-TO-PARKWAY ENTERING LANES TABLE 2.3 INTERSECTION ENTERING VOLUMES FOR THE PARKWAY-TO-PARKWAY NETWORK TABLE 3.1 ENTERING VOLUMES: FOUR-LANE PARKWAY TO FOUR-LANE PARKWAY TABLE 3.2 ENTERING VOLUMES: SIX-LANE PARKWAY TO FOUR-LANE PARKWAY TABLE 3.3 ENTERING VOLUMES: SIX-LANE PARKWAY TO SIX-LANE PARKWAY TABLE 3.4 ENTERING VOLUMES: EIGHT-LANE PARKWAY TO FOUR-LANE PARKWAY TABLE 3.5 ENTERING VOLUMES: EIGHT-LANE PARKWAY TO SIX-LANE PARKWAY TABLE 3.6 ENTERING VOLUMES: EIGHT-LANE PARKWAY TO EIGHT-LANE PARKWAY TABLE 3.7 VERIFICATION OF NEED TO GRADE-SEPARATE IDENTIFIED INTERSECTIONS TABLE 3.8 RIGHT-OF-WAY (R/W) REQUIREMENT FOR EACH INTERCHANGE TYPE TABLE 3.9 PARKWAY-TO-PARKWAY INTERSECTION ENTERING VOLUME VERSUS THRESHOLDS FOR DIFFERENT INTERCHANGE TYPES TABLE 4.1 RIGHT-OF-WAY REQUIREMENT FOR EACH INTERCHANGE TYPE TABLE 4.2 ANALYSIS OF EACH GRADE-SEPARATED INTERSECTION VERSUS INTERCHANGE TYPE TABLE 4.3 ESTIMATED COST OF DEVELOPING INTERCHANGE TYPES TABLE 5.1 TRAFFIC SIGNAL TIMING ASSUMPTIONS FOR THE PGSI TABLE 5.2 COMPARISON OF PGSI AND SPUI INTERCHANGE PERFORMANCE TABLE 6.1 ARIZONA PARKWAY LEVEL OF SERVICE THRESHOLD TABLE 6.2 FLARED PARKWAY-TO-PARKWAY INTERSECTIONS TABLE 6.3 RECOMMENDED GRADE-SEPARATED INTERCHANGE TYPE BY PARKWAY-TO-PARKWAY INTERSECTION Page ii

5 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study 1 Introduction 1.1 Background Acceptance of the Arizona Parkway concept evolved from a series of recently completed and on-going, long-range transportation studies in Maricopa and Pinal Counties. The City of Surprise first introduced this facility classification in the Surprise Transportation Plan, originally adopted in December, 2005 (updated July, 2008). Subsequently, the Maricopa Association of Governments (MAG) and its funding partners completed the I-10/Hassayampa Valley Roadway Framework Study (Hassayampa Valley Study) and initiated work on the I-8 and I-10/Hidden Valley Transportation Framework Study (Hidden Valley Study). Both studies embraced the Arizona Parkway facility as a critical component of the region s ultimate transportation network designed to serve Buildout planning horizon population and employment levels within planning areas established for the two studies. Definition of Buildout relies on full implementation of adopted general plans for all jurisdictions located within the planning areas defined for each study. There is no set timeframe within which Buildout will occur, but generally it is viewed as occurring within 40 to 60 years in the future. It is within this context that Maricopa County Department of Transportation (MCDOT) proceeded to address recommendations of the two framework studies conducted by MAG. The Arizona Parkway has been identified in these two studies as the facility of choice to serve high traffic volume corridors in the far West Valley. Therefore, MCDOT commissioned this study to assist it in evaluating the level of service in these corridors and establish required rights-of-way (R/W) for parkway-to-parkway intersections. Partnering with MCDOT, the Study Team members (identified below) have helped to identify significant corridor requirements for the future, including preferred intersection designs and R/W needs. this information, MCDOT and its study partners will be able to be proactive in identifying and preserving necessary R/W to assure full development of the region s major roadway system. 1.2 Purpose The Arizona Parkway is a roadway facility classification that has been adopted by MCDOT, the City of Goodyear, the Town of Buckeye, the City of Surprise. The Arizona Parkway design includes use of an intersection treatment referred to as the indirect left-turn (also known as the Michigan U-turn or median U-turn). This intersection treatment (shown in the diagram below) eliminates left-turns at all cross-streets and incorporates an extra wide median to facilitate U-turns downstream of cross-street intersections. These indirect left-turn operations provide additional travel capacity eliminating the need for full grade separation at most parkway-parkway intersections. However, grade-separated intersections may be required at certain high-volume locations. AZ Parkway /Interchange Analysis Study Team Committee Member Tim Oliver Nicolaas Swart Robert Herz Renee Probst Bob Hazlett Woody Scoutten Thomas Chelbanowski Cato Esquivel Luke Albert Dr. Robert Maki John Abraham Randall Overmyer Dan Marum Steve Pouliot James Witkowski Representing Maricopa County Department of Transportation Maricopa Association of Governments Representing Town of Buckeye City of Goodyear City of Surprise Wilson & Company Morrison-Maierle, Inc. This Arizona Parkway /Interchange Operational Analysis and Design Concepts Study was undertaken to review the Arizona Parkway network defined by the two regional transportation framework studies, establish at-grade parkway-to-parkway intersection thresholds, and identify where parkway-to-parkway interchanges will be needed. The results presented herein have been developed to provide a framework for categorizing future parkway-to-parkway intersection treatments for the purpose of protecting future R/W needs. The purpose of this study, therefore, was to perform a basic analysis of forecast Buildout traffic volumes at all proposed parkway-to-parkway crossing locations. This analysis was used to determine the daily entering volumes at the intersections and the threshold level at which an at-grade intersection fails and a grade-separated interchange is required. Once the threshold level for warranting upgrade to a traffic interchange was identified, an evaluation of interchange treatment alternatives was conducted to determine which type of treatment would best serve forecast traffic loadings. This evaluation resulted in development of a recommended interchange design treatment that minimizes the R/W footprint and would be applicable at all locations where an interchange will be required. Page 1-1

6 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study The primary product of the work program was a categorization of all parkway-to-parkway intersections and development of design templates for recommended grade-separated treatment solutions. This was accomplished by selecting traffic interchange treatments based on a series of operational and geometric concept design analyses. These technical recommendations have been supported by tabular and graphic summaries to document key findings, illustrate concept design sketches, and identify necessary R/W footprint limits for each recommended interchange treatment. A summary map has been prepared to designate a recommended intersection/interchange treatment for each parkway-to-parkway intersection in the combined planning area of the Hassayampa Valley and Hidden Valley Framework Studies. Nevertheless, decisions as to specific interchange type and design must await preparation of more detailed Design Concept Reports (DCRs), which will occur as development in affected areas proceeds. 1.3 Project Study Area The combined planning areas of the Hassayampa Valley and Hidden Valley Framework Studies occupy approximately 4,000 square miles of area in Maricopa and Pinal Counties (Figure 1.1). As noted above, long-range travel demand forecasts for these studies focused on Buildout conditions. The most recent Buildout travel demand forecast from these studies served as the basis for this analysis effort. The roadway networks defined for the planning areas of each study were reviewed and inventoried to identify the parkway-to-parkway intersections to be analyzed and categorized. The study area for this project constitutes approximately 3,300 square miles, including the Hassayampa Valley planning area and the western portion of the Hidden Valley planning area within Maricopa County (Figure 1.2). The project study area extends from I-8 in the south to SR-74 in the north and from SR-303L (Loop 303) on the east to 459 th Avenue on the west. It includes all of the communities of Buckeye, Gila Bend, Goodyear (including the Sonoran Valley), and Surprise. A small portion of western Glendale also lies within the project study area. Page 1-2

7 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 1.1 Hassayampa & Hidden Valley Framework Studies Planning Areas Figure 1.2 Arizona Parkway Interchange Design Study Area Page 1-3

8 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study 2 Arizona Parkway Network 2.1 Applicable Network Models As noted earlier, the two MAG regional framework studies served as the basis for assessing forecast travel demand on future parkway facilities in the study area under Buildout traffic conditions. Review and inventory of the two framework studies identified parkway-to-parkway intersections to be evaluated and categorized. 2.2 s Identified for Evaluation in the project study area, 62 parkway-to-parkway intersections were identified (Figure 2.1). Fifty-two intersections lie within the Hassayampa Valley planning area, and 10 lie within the Hidden Valley planning area. Of those located within the Hassayampa Valley planning area, 11 are south of I-10, which is the major east-west, high-capacity facility serving the West Valley. At Buildout, the combined Hassayampa/Hidden Valley study area will be served by the completed Loop 303/Estrella Freeway, the Hassayampa Freeway, which will run along the western side of the study area and through the central portion south of I-10, and the White Tanks Freeway, connecting Loop 303 to the Hassayampa Freeway. 2.3 Network Volumes The forecast daily volumes used in this analysis were derived from September 2008 MAG model runs using Buildout travel demand data from the two regional framework studies. A volume smoothing exercise was conducted to identify the highest volume level for segments containing multiple volume data. This accounted for the influence of centroid connectors as well as boundary segments that overlapped the two framework studies in the vicinity of the Gila River corridor in the Southwest Valley. The resulting volumes are depicted in Figure Network Recommendations Level of service (LOS) is a qualitative measure of traffic operations, combining measurement of the operational characteristics of traffic and the perception of traffic conditions by both motorists and passengers. Thus, the analysis of roadway segment LOS is based on the number of lanes, functional classification of the roadway, and desired LOS capacity expressed in terms of the daily traffic volume. Each LOS is given a letter designation from A to F, with A representing the optimal or best traffic conditions and F the worst. LOS provides an indication as to whether any given roadway or street segment will be under- or over-capacity at a given volume of traffic. The study area is comprised of fast growing urban and suburban as well as rural areas. Therefore, capacities used to define roadway segment LOS have been based on widely accepted guidelines developed for urban and rural areas. Generally, variable measurement acknowledges that more congestion is tolerated in developed urban and suburban areas than rural areas. However, for this study, LOS E was selected as the acceptable performance measure for all roadways in the study area, as the assumption for traffic volumes and flow rates are based on ultimate Buildout (i.e., fully urbanized) conditions. The focus of future transportation improvements should be to ensure traffic operations do not exceed this threshold. Table 2.1 shows traffic volume thresholds for LOS C, D, & E conditions for Arizona Parkway facilities with four-, six-, and eight-lane configurations. These thresholds were determined assuming a K-factor of and a peak-hour factor (PHF) of 1.0. The K-factor represents an estimate of the portion of daily volume that occurs during the peak-hour. It is the ratio of the peak-hour two-way traffic to the total two-way daily traffic volume for a given roadway segment. The assumed K-factor is based on engineering judgment of observed roadway characteristics, such as traffic type, roadway function, seasonal patterns, geographical location, functional classification, and volume group. In this case, the K-factor utilized for this analysis is consistent with current peak-hour conditions in the Phoenix metropolitan area, based on recent traffic data compiled by MAG. The PHF is simply the ratio of the peak-hour volume to four times the peak fifteen-minute volume. The PHF value of 1.0 recognizes the uniformity of saturated peak-hour traffic loads associated with Buildout conditions. Table 2.1 Arizona Parkway Level of Service Thresholds Average Daily Traffic Total Number of s (vehicles per day) (1) LOS C LOS D LOS E (2) 4 39,400 47,100 49, ,000 70,600 74, ,700 94,100 98,800 Notes: (1) Assumes a K = 0.075; balanced green time allocation per lane at high volume parkway-to-parkway intersections. (2) Assumes a capacity of 950 vehicles per hour (vph) per approach lane and a peak-hour factor (PHF) of 1.0. Shading indicates the maximum desirable daily volume level from the Arizona Parkway at LOS E LOS = Level of Service Source: Wilson & Company and Morrison-Maierle, October The LOS E maximum volume threshold (shaded) provides the basis for determining whether an operational deficiency may exist on these three differently configured facilities. That is to say, if projected traffic volumes exceed the LOS E volume threshold, it is concluded that facility capacity has likely been exceeded, and the roadway s ability to accommodate peak hour traffic may be deficient. For example, a 4-lane parkway with a traffic volume exceeding 49,400 vehicles per day (vpd) would be identified as operating at LOS F, as the traffic volume has exceeded the LOS E threshold. Therefore, the parkway is considered deficient in its capacity to accommodate assigned traffic volumes. The refined traffic volume assignments depicted in Figure 2.2 were compared to the LOS thresholds of Table 2.1 to identify the minimum number of lanes required for each parkway segment. The minimum lane requirements were then reviewed with regard to corridor cross-section continuity and jurisdictional input to arrive at a recommended number of lanes. Table 2.2 shows the resulting recommended number of lanes for each roadway segment. Figure 2.3 depicts the resulting recommended number of lanes for each parkway facility, on a segment-by-segment basis. It is important to note that the lane recommendations identified in Figure 2.3 are based on the capacity analysis conducted for this study rather than local plans or even the findings of the Hassayampa Valley Study. Also, this study focuses only on travel forecasts for parkway facilities under buildout conditions, prepared by MAG especially for this study in September, Page 2-1

9 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 2.1 Parkway-to-Parkway s in the Study Area Page 2-2

10 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 2.2 Study Area Buildout Parkway Network Segment Volumes Page 2-3

11 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Table 2.2 Segment Analysis for Parkway-to-Parkway Entering s Facility Name From To Daily Traffic Volume Capacity Based Recommended Number of s Requirement East-West , , , Dove Valley Pkwy , , , East of 8 39, West of , , , Jomax Pkwy , , , East of 15 37, , Deer Valley Pkwy , East of 18 79, , Sun Valley Pkwy , , West of , Bell Pkwy , East of , , Waddell Pkwy , , , , Northern Pkwy , , East of 32 98, , Camelback Pkwy , , , McDowell Pkwy , , East of , , , Buckeye Pkwy 44 East of 44 97, , East of 46 74, , , , Southern Pkwy , , , East of 51 94, Hazen Pkwy 52 East of 52 27, E-W 1 Pkwy 56 East of 56 78, SR-238 Pkwy , , Watermelon Pkwy , East of 62 65, Continued Page 2-4

12 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Table 2.2 Segment Analysis for Parkway-to-Parkway Entering s (Continued) Facility Name From To Daily Traffic Volume Capacity Based Recommended Requirement Number of s North-South North of , Tonopah Pkwy , , , Paloma Rd 60 South of 60 93, , Wintersburg Pkwy , , North of , , , , Hidden Waters Pkwy , , , , , , , , Palo Verde/Sun Valley Pkwy , , , South of 49 60, North of , , , Turner Pkwy , , , , South of , North of , , Wild Rose Pkwy , , , , Watson Pkwy , South of 50 52, North of , US-60 Pkwy , , South of 9 120, North of , Dean Pkwy , , , , , , Jackrabbit Trail/Perryville , Pkwy , , , , th Pkwy North of , South of 7 65, North of , Sarival Pkwy , South of , Cotton North of , North of , rd Pkwy , South of 62 52, th Ave 59 South of 59 72, Source: Hidden Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), MAG, 9/30/08. Hassayampa Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), 9/30/208. Prepared by Wilson & Company, 10/20/08, Rvsd 03/09/09. Page 2-5

13 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 2.3 Recommended Number of s for Buildout Parkway Network Page 2-6

14 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study 2.5 Entering Volumes As discussed in Section 2.3, the segment volumes used to develop network lane recommendations were indicative of the highest volume level for segments containing multiple volume data. For the intersection-level evaluation, MAG model volumes were identified separately for each intersection leg based on the volume in closest proximity to the subject intersection. These approach volumes were then use to determine entering volumes for each parkway-to-parkway intersection. Table 2.3 shows forecast average daily traffic volumes for each leg of the intersections evaluated and the intersection entering volumes, which are one-half of the two-way volumes on each leg, i.e., traffic volumes on each leg represent inbound and outbound traffic at the face of the intersection. The highest aggregate entering volumes are forecast to occur at the intersection of Sun Valley Parkway/Bell Road and Jackrabbit Trail in the City of Surprise ( #23). The eastbound and northbound average daily traffic volumes at this intersection are forecast to be 180,000 vpd or greater, resulting in an intersection entering volume of 302,500 vpd. The next highest aggregate intersection entering volumes are forecast to occur in the Town of Buckeye in connection with McDowell Parkway, where it crosses the existing Sun Valley Parkway (216,000 vpd) and the proposed Turner Parkway (247,000 vpd), s #38 and #39, respectively. Average two-daily traffic on all legs except one at these two intersections is forecast to exceed 100,000 vpd. The entering volume of 166,500 vpd at the proposed Hidden Waters Parkway and Watermelon Road intersection ( #61) in the Town of Gila Bend is lower than five other parkway-to-parkway intersections evaluated. However, the 143,000 vpd on the western leg of the intersection is especially notable. This volume exceeds all two-way traffic volumes in the study area, except those at #23. Page 2-7

15 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study ID # Table 2.3 Entering Volumes for the Parkway-to-Parkway Network Intersecting Roadway Names Average Two-Way Daily Traffic Volumes at Roadway (1) North / South East / West South Leg North Leg West Leg East Leg Entering Volume (2) 1 243rd Ave Joy Ranch Rd 57,000 59,000 64,000 51, ,500 2 Hidden Waters Pkwy (311th Ave) Dove Valley Rd 56,000 47,000 13,000 35,000 75,500 3 Turner Pkwy (267th Ave) Dove Valley Rd 65,000 64,000 37,000 47, , rd Ave Dove Valley Rd 51,000 50,000 59,000 61, ,500 5 US-60/Grand Avenue Dove Valley Rd 69,000 70,000 70,000 81, , th Ave Dove Valley Rd 95,000 67,000 81, , , th Ave Dove Valley Rd 65,000 62, ,000 77, , rd Ave Lone Mountain Rd 68,000 66,000 78,000 39, , th Ave US-60/Grand Avenue 79,000 67,000 69,000 84, , Hidden Waters Pkwy (315th Ave) Jomax Rd 58,000 56,000 45,000 65, , Turner Pkwy (267th Ave) Jomax Rd 77,000 86,000 54,000 61, , rd Ave Jomax Rd 68,000 46,000 64,000 75, , th Ave Jomax Rd 110,000 73,000 84, , Jackrabbit Trail (195th Ave) Jomax Rd 67, ,000 79, , rd Ave Jomax Rd 77,000 64, ,000 37, , Turner Pkwy (267th Ave) Deer Valley Rd 70,000 75,000 43,000 62, , rd Ave Deer Valley Rd 32,000 30,000 74,000 69, , Jackrabbit Trail (187th Ave) Deer Valley Rd 81,000 58,000 67,000 56, , Turner Pkwy (267th Ave) Sun Valley Pkwy 94,000 70,000 63,000 96, , rd Ave Sun Valley Pkwy 0 32, , , , Hidden Waters Pkwy (331st Ave) Bell Pkwy 49,000 44,000 55,000 47,000 97, Sun Valley Pkwy Bell Pkwy 41,000 58,000 60,000 31,000 95, Sun Valley Pkwy/Bell Rd Jackrabbit Trail (195th Ave) 180, , , , , Hidden Waters Pkwy (331st Ave) Cactus Rd 73,000 54,000 46,000 38, , Sun Valley Pkwy Sweetwater Ave 52,000 49,000 30,000 35,000 83, Turner Pkwy (267th Ave) Waddell Rd 66,000 84,000 36, , Tonopah Pkwy (411th Ave) Northern Ave 9,000 10,000 15,000 9,000 21, Wintersburg Pkwy (379th Ave) Northern Ave 37,000 40,000 32,000 35,000 72, Hidden Waters Pkwy (339th Ave) Northern Ave 72,000 73,000 41,000 16, , Sun Valley Pkwy Northern Ave 67,000 54,000 22,000 44,000 93, Turner Pkwy (267th Ave) Northern Ave 80,000 67,000 44, , Jackrabbit Trail (187th Ave) Northern Ave 71,000 85, ,000 91, Tonopah Pkwy (411th Ave) Camelback Rd 20,000 10,000 2,000 12,000 22, Wintersburg Pkwy (379th Ave) Camelback Rd 67,000 38,000 27,000 16,000 74, Hidden Waters Pkwy (339th Ave) Camelback Rd 93,000 76,000 56,000 33, , Sun Valley Pkwy Camelback Rd 105,000 80,000 43,000 13, , Hidden Waters Pkwy (339th Ave) McDowell Pkwy 92,000 93,000 28,000 61, , Sun Valley Pkwy McDowell Pkwy 116, ,000 97, , , Turner Pkwy (Turner Rd) McDowell Pkwy 127, , , , , Watson Pkwy McDowell Pkwy 40, , , , Tonopah Pkwy (403rd Ave) Van Buren St 25,000 10,000 17,000 22,000 37, Salome Hwy Van Buren St 12,000 17, ,000 17, Wintersburg Pkwy (379th Ave) Van Buren St 38,000 56,000 5,000 23,000 61, Hidden Waters Pkwy (339th Ave) Van Buren St 58,000 69,000 60,000 91, , Watson Pkwy Van Buren St 60,000 81,000 69, , , Perryville Rd Van Buren St 81,000 84,000 70,000 69, , Wintersburg Pkwy (379th Ave) Salome Hwy 0 38,000 12,000 50,000 50, Hidden Waters Pkwy (331st Ave) Southern Ave 85,000 73,000 73,000 79, , Palo Verde Rd Southern Ave 60,000 72,000 75, , , Watson Pkwy Southern Ave 52,000 50, , , , Perryville Rd Southern Ave 86,000 89, ,000 94, , Tonopah Pkwy (403rd Ave) Ellioit Rd 16,000 12,000 18,000 15,000 30, Cotton Pecos Rd 53,000 56,000 29,000 3,000 70, Rainbow Valley Rd Sonoran Valley Pkwy 0 12,000 3,000 37,000 26, Sonoran Valley Pkwy Dysart Rd 0 29,000 74, , , Sonoran Valley Pkwy Casa Blanca Rd 62, , , , Sonoran Valley Pkwy (107th Ave) SR-238 (Maricopa/Gila Bend Rd) 46,000 66,000 30,000 38,000 90, rd Ave SR-238 (Maricopa/Gila Bend Rd) 62,000 59,000 71,000 56, , th Ave SR-238 (Maricopa/Gila Bend Rd) 59,000 36,000 56,000 82, , Paloma Rd Watermelon Rd 74,000 39, , , Hidden Waters Pkwy (Old US-80) Watermelon Rd 24,000 84, ,000 82, , rd Ave Barnes Rd 52,000 57, ,000 80,000 Prepared by: Wilson & Company, 10/20/08 Sources: 1) Average Daily Two-Way Traffic Volumes north, east, south, and west of the intersection, e.g., North Leg identifies the two-way traffic on the roadway north of the intersection. Forecast volumes from Hidden Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), MAG, 9/30/08. Hassayampa Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), 9/30/208. 2) Entering Volume is equal to the sum of the Average Daily Two-Way Traffic Volumes on each leg of the intersection divided by two. Determined by Wilson & Company, 10/20/08. Page 2-8

16 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study 3 Arizona Parkway Network Analysis Figure 3.1 Maximum Threshold Volume Analysis Methodology 3.1 Entering Volume Capacity Thresholds Guided by the analysis of indirect left-turn intersections conducted by others, 1 daily capacity thresholds were established for six intersection configurations. Threshold values served as the basis for identifying whether or not the intersection will need to be at-grade or grade-separated, based on a comparison of daily entering volumes documented in Table 2.3 to the established thresholds Capacity Methodology Six parkway-to-parkway intersection configurations were identified based on the number of lanes on the applicable segments of intersecting facilities. The six intersection configurations shown below were selected to encompass the range of operational circumstances potentially present in the study area at Buildout: 4-lane to 4-lane (4-4) 6-lane to 4-lane (6-4) 6-lane to 6-lane (6-6) 8-lane to 4-lane (8-4) 8-lane to 6-lane (8-6) 8-lane to 8-lane (8-8). The Arizona Parkway indirect left-turn intersection concept was assumed for each of the six parkway-to-parkway intersection configurations. These were tested to determine at what daily capacity threshold the indirect left-turn concept would fail. Failure required that the location be marked for additional through lanes or grade-separation. As noted in Chapter 2, a LOS E was adopted as the threshold value for the planning-level evaluation of parkway segments. However, for the more specific analysis of parkway-to-parkway intersections, the LOS D condition, established by MCDOT guidelines for the County roadway system, was utilized for purposes of establishing design guidelines. The methodology for evaluating the threshold of at-grade, parkway-to-parkway intersections followed a three-step process: Estimate maximum average daily intersection entering volumes for each intersection type. Estimate maximum peak hour approach and turning movement volumes; Evaluate the intersection LOS and iteratively adjust volume until the threshold is attained. Figure 3.1 is a flow diagram depicting the general steps in this process Estimating Peak-Hour Volumes Peak-hour entering volumes on each intersection approach were derived assuming a peak-hour equal to 7.5 percent of daily traffic volume estimates (i.e., K-factor = 0.075), as well as a 60/40 directional split. That is to say, 60 percent of the daily peak-hour traffic volume would occur in the most heavily traveled direction entering the intersection. The model databases developed for the MAG framework studies were reviewed to obtain relevant guidance on turning movements in the study area. Turning-movement 1 MCDOT Enhanced Parkway Studies, Morrison-Maierle, Inc., 2007 and Page 3-1

17 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study volumes for the threshold analysis were based on the standard methodology for estimating future turning movements presented in National Cooperative Highway Research Program (NCHRP) Report The NCHRP methodology facilitates assessment of existing or assumed baseline turning-movement percentages, utilizing given future approach volumes, such as those provided through the framework study model outputs. It also allows calculated turning-movement volumes to be balanced to match the selected future approach volumes. Turning-movement volumes were developed for each indirect left-turn intersection configuration. Turning-movement analyses for the parkway-to-parkway intersections were based on the typical distribution of intersection turning movements 10% left, 75% through, 15% right and balanced through the intersection in accordance with the NCHRP methodology. Peak-hour factors and volume estimates were reviewed with the Technical Advisory Committee (TAC) prior to application in this study Identifying Volume Thresholds The AM and PM peak-hour turning movements were evaluated using Synchro analysis software with an 80-second cycle length and optimized splits for lane-volume distribution. Initially, all intersections were assumed to have one left-turn lane and two right-turn lanes. Subsequent testing of each intersection was conducted to determine if the double right-turn lanes were necessary. They were considered to be unnecessary, if the forecast right-turn traffic volume was less than 900 vehicles per hour (vph). Final intersection evaluations used one left-turn lane and one right-turn lane. As indicated in Figure 3.1, volumes then were adjusted in five percent increments through multiple iterations until the intersection was just over the LOS D/LOS E boundary. 3 Once the peak-hour volume threshold was identified, it was converted back to a daily volume threshold based on the 7.5 percent peak-hour ratio. Analysis revealed that traffic volumes at the main parkway/parkway intersection were first to surpass the LOS D/LOS E boundary, rather than those at the indirect left-turn locations. Figure 3.2 graphically displays the results of this indirect left-turn intersection analysis, specifically the entering daily volume thresholds calculated for the six intersection configurations. The lowest entering-volume threshold established employing the above methodology is 81,000 daily trips for the 4-4 intersection type. The graph generally indicates that an increase of the entering volume by 15,000 to 20,000 daily trips will require the addition of two through lanes to the total number of lanes serving the intersection. For example, a six-lane parkway intersecting with a four-lane parkway will have a threshold of 96,000 daily trips. When the entering volume reaches 96,000 daily trips, two additional lanes will be needed for the four-lane legs of the intersection. 3.2 Entering-Volume Thresholds for Interchange/ s Entering-volume thresholds were used to indicate when at-grade intersection operations would fail, requiring grade separation of traffic. After this determination was made, several grade-separated interchange types were evaluated to determine the best solution for each intersection. Figure 3.2 Maximum Daily Entering Volume Thresholds by At- Type At-/ Threshold Analysis Each intersection in the study area was tested with reference to established thresholds to identify which intersections could operate at-grade and which intersections would need to be grade-separated. The threshold test for grade separation assumed intersections could be flared to accommodate additional lanes, if necessary to provide additional capacity. Review of the flared-lane concept by the TAC resulted in the conclusion that the typical build scenario would be from the outside in (i.e., toward the median). Thus, additional lanes at the intersection approach would be flared to the left approaching the intersection, and traffic would diverge to the left. Post-intersection lanes would merge to right, and traffic would merge to the right. Based on TAC recommendations, the analyses assumed a balanced ratio of effective green time to cycle length (G/C) for all approaches to any given intersection with the understanding that final assessment of each intersection would be accomplished during preparation of the required DCR. Table 3.1 thru Table 3.6 shows the results of the analysis. 2 3 National Cooperative Highway Research Program Report 255, Highway Traffic Data for Urbanized Area Project Planning and Design, p LOS D is consistent with MCDOT Roadway Design Manual Guidelines for desired level of service for high-volume urban facilities. Page 3-2

18 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study ID # Entering Volume (1) Table 3.1 Entering Volumes: Four- Parkway to Four- Parkway Assumed Base Configuration (2) Maximum Entering Threshold Volume (3) Verification Threshold- Volume Based Configuration ADT Threshold Volume Verification 27 16, ,000 < Threshold ,000 < Threshold 28 72, ,000 < Threshold ,000 < Threshold 33 22, ,000 < Threshold ,000 < Threshold 41 37, ,000 < Threshold ,000 < Threshold 42 17, ,000 < Threshold ,000 < Threshold 52 30, ,000 < Threshold ,000 < Threshold 54 26, ,000 < Threshold ,000 < Threshold Prepared by: Wilson & Company, NOTES: (1) Sum of approach leg volumes from MAG model data (see source). (2) Base intersection lane configuration derived from minimum number of approach lanes to accommodate approach volumes documented in Table 2.3. (3) ADT threshold volume revised Source: Hidden Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), MAG, 9/30/2008. Hassayampa Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), 9/30/2008. ID # Entering Volume (1) Table 3.2 Entering Volumes: Six- Parkway to Four- Parkway Assumed Base Configuration (2) Maximum Entering Threshold Volume (3) Verification Threshold- Volume Based Configuration ADT Threshold Volume Verification 2 75, ,000 < Threshold ,000 < Threshold 3 106, ,000 ADD LANES , , ,000 ADD LANES , , ,000 ADD LANES , , ,000 ADD LANES ,000 s Acceptable s Acceptable s Acceptable s Acceptable 25 83, ,000 < Threshold ,000 < Threshold , ,000 ADD LANES ,000 s Acceptable 30 93, ,000 < Threshold ,000 < Threshold 34 74, ,000 < Threshold ,000 < Threshold 43 61, ,000 < Threshold ,000 < Threshold 47 50, ,000 < Threshold ,000 < Threshold 53 70, ,000 < Threshold ,000 < Threshold 57 90, ,000 < Threshold ,000 < Threshold Prepared by: Wilson & Company, NOTES: (1) Sum of approach leg volumes from MAG model data (see source). (2) Base intersection lane configuration derived from minimum number of approach lanes to accommodate approach volumes documented in Table 2.3. (3) ADT threshold volume revised Tan shading identifies the proposed lane configuration required to satisfy intersection entering volume. Source: Hidden Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), MAG, 9/30/2008. Hassayampa Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), 9/30/2008. Page 3-3

19 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study ID # Entering Volume (1) Table 3.3 Entering Volumes: Six- Parkway to Six- Parkway Assumed Base Configuration (2) Maximum Entering Threshold Volume (3) Verification Threshold- Volume Based Configuration ADT Threshold Volume 1 115, ,000 ADD LANES ,000 Verification s Acceptable (4) 4 110, ,000 < Threshold ,000 < Threshold , ,000 < Threshold ,000 < Threshold 22 95, ,000 < Threshold ,000 < Threshold , ,000 ADD LANES ,000 s Acceptable 62 80, ,000 < Threshold ,000 < Threshold Prepared by: Wilson & Company, NOTES: (1) Sum of approach leg volumes from MAG model data (see source). (2) Base intersection lane configuration derived from minimum number of approach lanes to accommodate approach volumes documented in Table 2.3. (3) ADT threshold volume revised (4) Though entering volumes exceed the capacity threshold, supplemental analysis indicated that the proposed lane configuration provides acceptable intersection operations. Tan shading identifies the proposed lane configuration required to satisfy intersection entering volume. Source: Hidden Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), MAG, 9/30/2008. Hassayampa Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), 9/30/2008. ID # Entering Volume (1) Table 3.4 Entering Volumes: Eight- Parkway to Four- Parkway Assumed Base Configuration (2) Maximum Entering Threshold Volume (3) Verification Threshold- Volume Based Configuration ADT Threshold Volume , ,000 ADD LANES ,000 Verification s Acceptable 26 93, ,000 < Threshold ,000 < Threshold 31 95, ,000 < Threshold ,000 < Threshold 32 91, ,000 < Threshold ,000 < Threshold , ,000 ADD LANES , , ,000 ADD LANES ,000 s Acceptable s Acceptable (4) , ,000 < Threshold ,000 < Threshold Prepared by: Wilson & Company, NOTES: (1) Sum of approach leg volumes from MAG model data (see source). (2) Base intersection lane configuration derived from minimum number of approach lanes to accommodate approach volumes documented in Table 2.3. (3) ADT threshold volume revised (4) Though entering volumes exceed the capacity threshold, supplemental analysis indicated that the proposed lane configuration provides acceptable intersection operations. Tan shading identifies the proposed lane configuration required to satisfy intersection entering volume. Source: Hidden Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), MAG, 9/30/2008. Hassayampa Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), 9/30/2008. Page 3-4

20 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study ID # Entering Volume (1) Table 3.5 Entering Volumes: Eight- Parkway to Six- Parkway Assumed Base Configuration (2) Maximum Entering Threshold Volume (3) Verification Threshold- Volume Based Configuration ADT Threshold Volume 5 145, ,000 ADD LANES , , , ,000 Verification s Acceptable 8 125, ,000 < Threshold ,000 < Threshold , ,000 ADD LANES ,000 s Acceptable , ,000 < Threshold ,000 < Threshold , ,000 < Threshold ,000 < Threshold , ,000 < Threshold ,000 < Threshold , ,000 < Threshold ,000 < Threshold , ,000 < Threshold ,000 < Threshold , ,000 ADD LANES , , ,000 ADD LANES , , , , , , , , , ,000 s Acceptable s Acceptable , ,000 < Threshold ,000 < Threshold , ,000 < Threshold ,000 < Threshold , ,000 < Threshold ,000 < Threshold Prepared by: Wilson & Company, NOTES: (1) Sum of approach leg volumes from MAG model data (see source). (2) Base intersection lane configuration derived from minimum number of approach lanes to accommodate approach volumes documented in Table 2.3. (3) ADT threshold volume revised Tan shading identifies the proposed lane configuration required to satisfy the demand of intersection entering volume. Light green shading identifies intersections where additional lanes will not satisfy entering volume, requiring a grade-separated interchange. ID # Entering Volume (1) Table 3.6 Entering Volumes: Eight- Parkway to Eight- Parkway Assumed Base Configuration (2) Maximum Entering Threshold Volume (3) 6 178, ,000 Verification Threshold- Volume Based Configuration ADT Threshold Volume ,000 Verification 9 149, ,000 < Threshold ,000 < Threshold , ,000 < Threshold ,000 < Threshold , ,000 < Threshold ,000 < Threshold , , , , , , , , , , , , , , , , , , , , , , , ,000 Prepared by: Wilson & Company, NOTES: (1) Sum of approach leg volumes from MAG model data (see source). (2) Base intersection lane configuration derived from minimum number of approach lanes to accommodate approach volumes documented in Table 2.3. (3) ADT threshold volume revised Light green shading identifies intersections where additional lanes will not satisfy entering volume, requiring a grade-separated interchange. Source: Hidden Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), MAG, 9/30/2008. Hassayampa Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), 9/30/2008. Source: Hidden Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), MAG, 9/30/2008. Hassayampa Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), 9/30/2008. Page 3-5

21 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study The first column in each of the tables identifies the intersection according to the study area numbering. The second column identifies the calculated intersection entering volume from the MAG data (see Table 2.3). The third column indicates the assumed number of lanes entering the intersection based on the segment volumes of Table 2.2. The fourth column indicates the calculated maximum entering volume for the intersection type assumed by the lane configuration (see Figure 3.2). The fifth column is a verification of number of lanes needed for the intersection to operate below the maximum entering volume. This column compares the entering volume to the maximum threshold volume. If the entering volume is less than the maximum threshold volume, the intersection is identified with < Threshold, meaning less than threshold. If the entering volume is greater than the maximum threshold volume, the column shows ADD LANES, indicating a need for additional lanes. The sixth column presents the proposed lane configuration adding lanes, if necessary, based on the assessment presented in column five. Column seven presents the results of evaluating the proposed lane configuration versus the maximum threshold volume. The s Acceptable conclusion in the final column indicates the intersection was tested to determine if the additional lanes would work for that particular intersection and that the additional lanes were sufficient. This column also identifies those intersections where grade separation will be the required design treatment. Thus, in some cases in the 8-6 lane configuration, the entering volume was identified to be too great to meet the threshold criteria even if additional lanes were added. These intersections were identified as. In all cases with the 8-8, if the entering volume was greater than the maximum threshold volume, the intersections were identified as not wanting to have a 10-lane parkway. The analysis reveals there are 13 intersections that likely would need to be grade-separated. The TAC requested testing of these 13 intersections with model run information to assess the impact of unbalanced approach volumes inherent in the actual intersection operations Threshold Capacity Based on the analysis methodology described for intersection thresholds in Section 3.1, the maximum threshold volumes initially were derived for three grade-separated interchange types. The results of this analysis are shown in Figure 3.3. For comparison, Figure 3.3 also shows the maximum entering volume capacity of a typical arterial intersection and an indirect left-turn intersection associated with the Michigan Indirect Left-Turn (MLT) Parkway design. It is important to note that threshold values calculated for the grade-separated interchange types are based on typical conditions. Given that each interchange type can be better or worse than another as site-specific conditions change, each intersection identified as requiring grade-separation was evaluated with site-specific conditions. The results of this evaluation are presented below. Having determined the entering thresholds at which grade separation would be required and identified those intersections that were candidates for grade separation, an analysis was performed to verify the need to grade separate the intersecting parkways. Table 3.7 shows the entering volumes of each leg and the total entering volume of 13 intersections determined to need grade separation. Based on delay analysis, the LOS for these intersections was determined to confirm whether or not grade separation was definitely necessary. As shown in Table 3.7, each these intersections would have an LOS of E or F and, therefore, definitely require grade separation. All other intersections operate at LOS D or better. Figure 3.3 Maximum Daily Entering Volume Threshold by Interchange Type 3.3 -Separated Interchange Concept Designs Three parkway-to-parkway interchange types were identified in concept to provide a basis for the operations analysis of each intersection. The concept design for each interchange assumes that the parkway median section is narrowed to reduce footprint on the bridge, as necessary. In each case, the higher volume parkway is given the priority for grade separation, and traffic signal operations on the minor parkway are maximized to provide the best progression for all approaches to the intersection. Design summaries for each interchange type are presented below. More detailed concept drawings are presented in Figure 3.4 to Figure 3.6. Page 3-6

22 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Table 3.7 Verification of Need to -Separate Identified s Leg ID # South North West East Total Entering Volume Total Delay for 8- x 8- (seconds) Level of Service (LOS)? 6 95,000 67,000 81, , , F Y 7 65,000 62, ,000 77, , F Y 19 94,000 70,000 63,000 96, , F Y , , , , ,500 1,465 F Y , ,000 97, , , F Y , , , , , F Y 45 60,000 81,000 69, , , F Y 46 81,000 84,000 70,000 69, , E Y 48 85,000 73,000 73,000 79, , F Y 49 60,000 72,000 75, , , F Y 50 52,000 50, , , , F Y 51 86,000 89, ,000 94, , F Y 61 24,000 84, ,000 82, , F Y Source: Wilson & Company, January 20, Single-Point Urban Interchange (SPUI) A single-point urban interchange (also referred to as a single-point diamond interchange), although not inherently restricted to urban environments, is a signalized intersection with a single traffic control (see graphic at right). Left-turns from ramps at the cross-street, which facilitate exiting the major street, are aligned such that they oppose each other. At-grade movements of the intersection are served by a three-phase signal. Relatively long cycle lengths are typical. This is due, in part, to longer intervals required to allow vehicles to clear the intersection. Principal Characteristics 3-phase signal operation Clearance intervals are extended Less pedestrian friendly 4 crossings Higher structural cost Low R/W requirement Moderate coordination with surrounding signals Serves very high traffic volumes Operates best with balanced left turns Moderate left-turn conflicts 4 Higher design speed on arterial crossing 24 points of conflict Standard Diamond Interchange The standard diamond interchange design physically separates through movements on the major street from other turning movements, which typically are served by one or two intersections (ramp terminals) on the minor street. On- and off-ramps, to/from the major street, respectively, connect to the ramp terminals, forming the shape of a diamond (see graphic at right). Diamond interchanges have a variety of forms, and efficient function of the design depends on separation between the two ramp terminals and the associated traffic control strategy. Principal Characteristics 3-phase signal operation Moderate clearance intervals More pedestrian friendly 2 crossings Moderate structural cost Moderate R/W requirement Easier to progress with adjacent signals Serves moderate-to-high traffic volumes Operates independently of balanced left turns Moderate left-turn conflicts 4 Higher design speed on arterial crossing 30 points of conflict Diverging Diamond Interchange (DDI) The DDI is a form of diamond interchange in which traffic in both directions on the cross-street shifts to the opposite side of the roadway at the major street. This design is unusual in that traffic on the overpass (or underpass) briefly moves on the opposite side of the road then transitions back to normal operations. The principal feature of the DDI is that no left turns must clear opposing traffic. Although all movements are discrete and most are controlled by traffic signals, there are only two clearance intervals (the time for traffic signals to change from green to yellow to red) instead of the six or more associated with other interchange designs. Page 3-7

23 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Principal Characteristics 2-phase signal operation with short cycle lengths Fewer clearance intervals Less pedestrian friendly 4 crossings Lower structural costs per lane High R/W requirement; varies with design speed Can be used to retrofit existing interchange Coordinates with 2-phase parkway signals Minimizes left-turn conflicts 2 Lower design speed on arterial crossing Violates driver expectations Reduces traffic queues Operates best with balanced left turns 21 points of conflict Separated Interchange Operations Analysis After verifying that 13 parkway-to-parkway intersections would need to be grade-separated to accommodate forecast traffic volumes, each interchange design type was modeled in Synchro/SimTraffic for each intersection to determine whether it would satisfy forecast traffic volumes. The results of this analysis are presented in Table 3.9. Table 3.9 reveals that any of the three grade separations generally would be an acceptable treatment for 9 of the 13 intersections identified as requiring grade separation. The exceptions are: s #23, # 38, #39 and #61. These locations are forecast to have exceptionally high daily volumes and, therefore, additional grade-separation of certain turning-movements may be necessary. Table 3.8 summarizes the R/W impact of each interchange type. The R/W shown in the table represents the amount of R/W required for the interchange in addition to the 200-foot R/W guideline established for all approaches to the parkway-to-parkway intersection. This concept-level analysis does not account for site-specific conditions, which may reduce or increase the amount of R/W impact (i.e. drainage, utilities, railroad). In addition, the concept analysis incorporate conservative estimates for side slope conditions. Table 3.8 Right-of-Way (R/W) Requirement for Each Interchange Type Interchange Type Total Additional Right-of-Way (R/W) (Acres) (1) Standard Diamond 29.0 Single Point Urban 19.1 Diverging Diamond 30.6 Notes: (1) Acreage represents the additional R/W required beyond the 200-foot R/W established in Design Guideline Recommendations for the Arizona Parkway, which is applicable to all intersection approaches. Source: Wilson & Company, May, Page 3-8

24 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 3.4 Standard Diamond Interchange Parkway Concept Design Page 3-9

25 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 3.5 Single Point Urban Interchange Parkway Concept Design Page 3-10

26 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 3.6 Diverging Diamond Interchange Parkway Concept Design Page 3-11

27 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study ID # Notes: Table 3.9 Parkway-to-Parkway Entering Volume versus Thresholds for Different Interchange Types Standard Diamond Single Point Urban Diverging Diamond Indicates that the identified interchange type will operate with an acceptable Levels of Service (LOS D or better) under build out traffic volume conditions during both the AM and PM peak hours for the specified intersection. - Indicates the identified interchange type will NOT operate at Level of Service D or better during both the AM and PM peak hours, based on forecast traffic volumes under Buildout conditions; therefore, this interchange type is not recommended for the specified intersection. Source: Wilson & Company, 4/27/2009 Page 3-12

28 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study 4 Parkway -Separated Interchange (PGSI) The future parkways are designed for, and anticipated to carry, very high traffic volumes, and the intersection of two parkways potentially could result in over 200,000 vehicles per day entering the intersection. Traffic volumes of this magnitude cannot be accommodated by an at-grade intersection and, typically, are serviced by some type of grade-separated interchange, such as the three described in the previous chapter. Therefore, subsequent to analyses of initial interchange designs for the parkway, the TAC pursued a new interchange concept specifically developed for application at the intersection of two Arizona Parkways, where forecast traffic volumes exceed the capacity of an at-grade intersection. 4.1 The Parkway -Separated Interchange Concept The concept behind the new interchange analysis was an interchange design that would (1) maintain consistency with the indirect left-turn treatment associated with linear travel on the parkway, and (2) accommodate the high-volume parkway intersections. During the process of evaluating various parkway-to-parkway intersection design options, a new concept for a grade-separated interchange was developed by the members of the Project Team, with encouragement from and participation by MCDOT staff. The new design concept is referred to as the Parkway -Separated Interchange (PGSI) Design Description The underlying principle of the design is that it incorporates the indirect left-turn movements of an at-grade intersection while maintaining a two-phase signal operation. Thus, this concept maintains for each intersecting parkway a traffic flow treatment consistent with that experienced at the at-grade intersections along the entire parkway. The commonly used SPUI and Diamond grade-separated interchange concepts accommodate the left-turn movement in the manner of a traditional at-grade intersection. The PGSI concept treats each approach to the interchange in exactly the same manner of design, assuring the driver of the same experience on all legs of the interchange. In addition, the concept can be designed to allow access to land in each quadrant of the interchange. Figure 4.1 shows the result of the PGSI concept design effort Principal Characteristics of the PGSI 2-phase signal operation with 80-second cycle lengths Coordinates with 2-phase parkway signals One signal per approach Double left turn at crossover and two-lane ramp Right turns to cross street are signalized U-turns at crossover permitted for the inside left Less pedestrian friendly with crossings at two locations per ramp Lower structural costs Low R/W requirement; varies with design speed Minimizes left-turn conflicts 4 Lower design speed on arterial crossing Meets driver expectations Reduces traffic queues 16 points of conflict Operational Analysis Like the other interchanges, the PGSI was evaluated in Synchro to identify the maximum average daily threshold volume. The results of the analysis are shown in Figure 4.2. Figure 4.2 shows the PGSI provides a high-capacity design with the ability to carry higher entering volumes than the other interchange types. The PGSI has entering volume thresholds of 216,100 and 247,000 vehicles per day (vpd) for the 8-6 and 8-8 intersections, respectively. This compares to the Michigan Indirect Left-Turn (at-grade) Parkway intersection, which has significantly lower thresholds for these two roadway configurations. The thresholds for the SPUI, which has the highest thresholds of the typical diamond-type interchanges, are four percent and 14 percent below those of the PGSI for the 8-6 and 8-8 lane configurations, respectively. A more detailed traffic operations analysis of this PGSI interchange concept is presented in Chapter Five. The R/W analysis of the PGSI revealed the additional R/W needed is less than the other interchange types. This is due mainly to the parkway-to-parkway ramps being generally at-grade, whereas the typical interchange requires additional R/W for embankment to raise the ramps to meet the crossing parkway. Table 4.1 shows the R/W comparison between the PGSI and the other interchange types. Table 4.2 summarizes the ability of each of the four interchange types evaluated to accommodate the traffic volumes forecast to occur at Buildout. The table shows that none of the designs, including the PGSI, is capable of accommodating forecast traffic at s #23 and #61. However, the PGSI in combination with direct connect or flyover ramps can accommodate the traffic volumes of these two intersections. Although the PGSI works for the majority of the intersections requiring grade separation, two excessively high-volume locations on the parkway network will require more than a typical gradeseparated interchange regardless of type. These two intersections #23: Sun Valley Parkway/Bell Road at Jackrabbit Parkway (Surprise), and #61: Watermelon Parkway at Hidden Waters Parkway (Buckeye) will require direct connector and flyover ramps to accommodate high-volume turning movements. The direct connections and flyover ramps will require additional R/W. Figures 4-3 and 4-4 show concept designs developed to incorporate direct connector/flyover ramps with the PGSI at these two intersections. 4.2 Pedestrian Access and Safety The high-capacity quality of the PGSI design is not conducive to easy pedestrian movements. First, the parkway intersections requiring this design will be six to eight lanes wide with a center median of 50 to 60 feet. Thus, pedestrian movements across the Arizona Parkway must be carefully planned and controlled. Pedestrian movements at a PGSI will be complicated due to the high volume of turning movements. Linear pedestrian movements will not be an issue, as the Arizona Parkway urban cross-section includes a six-foot sidewalk and seven-foot landscape buffer to accommodate pedestrian and bicycle movements. Page 4-1

29 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 4.1 Parkway -Separated Interchange Concept Design Page 4-2

30 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 4.2 Maximum Daily Entering Volume Threshold by Interchange Type Including the PGSI Table 4.1 Right-of-Way Requirement for Each Interchange Type ID # Notes: Table 4.2 Analysis of Each -Separated Versus Interchange Type Standard Diamond Single Point Urban Diverging Diamond Parkway - Separated Indicates that the identified interchange type will operate with an acceptable Levels of Service (LOS D or better) under build out traffic volume conditions during both the AM and PM peak hours for the specified intersection. - Indicates the identified interchange type will NOT operate at Level of Service D or better during both the AM and PM peak hours, based on forecast traffic volumes under Buildout conditions; therefore, this interchange type is not recommended for the specified intersection. Source: Wilson & Company, 4/27/2009 Total Additional Right-of-Way (R/W) Interchange Type (Acres) 1 Standard Diamond 29.0 Single Point Urban 19.1 Diverging Diamond 30.6 Parkway -Separated 14.8 Notes: (1) Acreage represents the additional R/W required beyond the 200-foot R/W established in Design Guideline Recommendations for the Arizona Parkway, which is applicable to all intersection approaches. Source: Wilson & Company, May, Page 4-3

31 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 4.3 Parkway -Separated Interchange Concept Design with High Volume Direct Connector/Flyover Ramp: #23 Sun Valley Parkway/Bell Road at Jackrabbit Trail Parkway Page 4-4

32 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 4.4 Parkway -Separated Interchange Concept Design with High Volume Direct Connector/Flyover Ramp: #61 Hidden Waters Parkway at Watermelon Parkway Page 4-5

33 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study respect to pedestrian crossings of the parkway facilities, the Design Guideline Recommendations for the Arizona Parkway published by MCDOT provides only the following guidance: a three-legged intersection, a crosswalk should only be installed when a signal is present. The crosswalk will only allow pedestrians to cross one-half of the Parkway and should only be installed when the remaining one-half of the Parkway can be crossed at an adjacent signalized intersection in close proximity, desirably less than 200. In general, most three-legged intersections should not include pedestrian crossings. Pedestrian crossings between full median breaks need to be evaluated on a case-by-case basis. A four-legged collector intersection can also be operated in a similar manner as described above without a full median break. Both approaches from the side-street would be required to turn right. A full median break should only be considered in the cases where a large volume of through traffic is anticipated on the side-street. In this case, a full median break can be provided as long as the one-half mile minimum spacing requirement is satisfied. The unique character of the parkway-to-parkway intersection and the impedance to pedestrian movements created by the intersection of two parkway facilities is complicated when an interchange requirement is established. A concept for pedestrian movements has been developed; however, more detailed evaluation and refinement will need to be conducted on a case-by-case basis to reach an optimal solution for addressing specific pedestrian movements and traffic levels. Figure 4.5 shows arrows indicating the manner in which pedestrians could negotiate the interchange, based on typical movements at other intersections in use today. Essentially, absent special overcrossings or undercrossings, pedestrians could traverse the major roadway of the interchange in one of two ways: (1) perform an indirect right-turn movement (opposite to vehicular movements) to get to the opposite side of the parkway, or (2) continue to the first street level crosswalk and us a pedestrian-actuated crossing signal that would be synchronized with the left-turn movement. To preclude this requirement, several methods have been identified that would permit direct (or, at least, more direct) travel patterns for pedestrians in the interchange area. On those legs of the Minor Parkway (in terms of directional volumes) that are rising over the Major Parkway, an undercrossing (see photo at right) could be installed that takes advantage of the elevation change required for the overpass. These undercrossings could be at the stop bar for traffic approaching the interchange, i.e., where the left-turn movements occur. The elevation change for the overpass would permit a minimal amount of excavation. Undercrossings would facilitate direct crossing to the other side of the Minor Parkway and provide maximum safety for pedestrians. Although this concept would take advantage of the elevation change, there still may be a need to depress the approach to the undercrossing from street level. Unfortunately, the same opportunity for an undercrossing does not exist for the Major Parkway, which would be constructed entirely at-grade. While it is possible to create an undercrossing of the at-grade parkway, even a slightly elevation of the roadway through lanes would elevate the entire interchange. Short of a significant design accommodation for an undercrossing at the left-turn intersection, pedestrian movements will need to be directed through the interchange to the area of the on-ramp in the direction of their travel. At the on-ramp, a pedestrian-actuated crossing signal could be installed and coordinated with the left-turn movement of the parkway to minimize delay. This would permit the pedestrian to go in the direction of the cross street by reaching the left-turn intersection of either roadway. A crosswalk or undercrossing would be provided outside the left-turn bays to accommodate pedestrian movements across the Major Parkway. The crosswalk would be aligned with the stop bar of the approach to the interchange. In any case, pedestrian-actuated signals on the out-bound legs of the interchange could jeopardize capacity of the interchange. A traffic signal progression analysis will need to be conducted to determine the effect of pedestrian movements. Figure 4.5 Typical PGSI Pedestrian Movement Pattern Source: Developed by Wilson & Company, June, Page 4-6

34 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study 4.3 Mainline Access Management The MCDOT Design Guideline Recommendations for the Arizona Parkway provides guidance regarding vehicular access to the parkway facility. The details of this guidance are not repeated here. Figure 4-6 shows how the typical access plan for the Arizona Parkway integrates with the PGSI interchange concept. Traffic on the three lanes approaching the interchange on the six-lane parkway would spread to four lanes after the signal, which facilitates the left-turn from the opposite direction. Through traffic on the four lanes approaching the left-turn bay and signal on the eight-lane parkway would merge prior to the signal and pass through the intersection. in a one-half mile segment downstream of the interchange, there could be at least four points of access along the approach lanes (i.e., downstream of a parkway-to-parkway intersection). Fewer access points are shown downstream of the PGSI, as it would not be advisable to have access points interfering with traffic merging into parkway traffic from the ramp that effectively accommodates the right-turn movement from one parkway to the other. 4.4 Cost Opinion Table 4.3 provides an estimate of the costs associated with developing and constructing the four interchange types evaluated within the framework of this study. Cost estimates include four elements: Right-of-Way estimated in acres and cost per acre; Structures and walls estimated by size (span, width, and square feet); Earthwork and Surface Preparation estimated in cubic yards; and Additional Requirements Utilities, Drainage, Traffic Control, Signing/Striping/Signals, Lighting, Mobilization, and Contingencies estimated as a percentage of the cumulative sum of the previous three elements. The most expensive option is the SPUI at $31.4 million. Although the SPUI presents some savings in R/W, with the associated cost for Structure/Walls is significantly higher than for the other interchange types. This generally is related to the constrained, criss-crossing design/configuration to accommodate left-turns, which requires the central portion of the intersection to be larger and more substantial compared to the other interchange types. The PGSI concept developed during this study is estimated to be the lowest cost option at $21.3 million. Even though the PGSI represents a savings of only a few million dollars relative to the Diamond and Diverging Diamond interchange types, this concept requires the least amount of R/W and disruptive Earthwork/Surfacing. In this light, the PGSI offers definite advantages for an urbanizing area. RIGHT OF WAY Cost Category Table 4.3 Estimated Cost of Developing Interchange Types Standard Diamond Interchange Diverging Diamond Interchange Single Point Urban Interchange Parkway - Separated Interchange Acres $/Acre (1) $135,000 $135,000 $135,000 $135,000 Subtotal Right-of-Way $4,725,000 $4,050,000 $2,700,000 $2,025,000 STRUCTURES Bridge Span (ft) Bridge Width (ft) Total square feet 22,500 18,750 34,500 23,000 $/square feet $200 $200 $210 $200 Subtotal Structures $4,500,000 $3,750,000 $7,245,000 4,600,000 EARTHWORK Cubic yards 325, , , ,000 $/cubic yard $10 $10 $10 $10 Subtotal Earthwork $3,250,000 $3,250,000 $3,000,000 $1,500,000 SURFACING $2,000,000 $2,000,000 $2,000,000 $2,000,000 SUBTOTAL $14,475,000 $13,050,000 $14,945,000 $10,125,000 ADDITIONALS Utilities 10% $1,447,500 $1,305,000 $1,494,500 $1,012,500 Drainage 20% $2,895,000 $2,610,000 $2,989,000 $2,025,000 Traffic Control 15% $2,171,250 $1,957,500 $2,241,750 $1,518,750 Signing/Striping/Signals 10% $1,447,500 $1,305,000 $1,494,500 $1,012,500 Lighting 10% $1,447,500 $1,305,000 $1,494,500 $1,012,500 Mobilization 20% $2,895,000 $2,610,000 $2,989,000 $2,025,000 Contingency 25% $3,618,750 $3,262,500 $3,736,250 $2,531,250 Subtotal Additionals $15,922,500 $14,355,000 $16,439,500 $11,137,500 TOTAL ESTIMATED CONSTRUCTION COST (2) $30,397,500 $27,405,000 $31,384,500 $21,262,500 Prepared by Wilson & Company, June, Notes: (1) Right-of-way cost estimates are based on recent acquisition costs in Maricopa County and reflect an assumed average for entitled and unentitled land costs. (2) Total estimated construction cost estimates are based on concept level details and are provided FOR COMPARISON purposes only. Page 4-7

35 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 4.6 Access Management Concept for PGSI and Arizona Parkway (6- to 8-) Page 4-8

36 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study 5 Detailed Traffic Operations Analysis of the Parkway -Separated Interchange A previous study of the Arizona Parkway concept included detailed traffic operations assessments of various parkway-to-parkway intersection concepts. 4 This previous work focused primarily on at-grade intersection alternatives. However, it did include analysis of a Single Point Urban Interchange (SPUI), which is a grade-separated design. The SPUI was found to provide the best overall traffic operations for a parkway-to-parkway interchange among alternative interchange designs, as a large volume of through traffic on one of the intersecting parkways does not experience traffic delay due to a traffic signal. Given the favorable report for the SPUI, it was considered desirable to compare traffic operations of the PGSI to that of the SPUI under the same traffic demand assumptions. Therefore, a special study was commissioned to provide a detailed traffic operations analysis of a new interchange concept that was specifically developed for application at the intersection of two Arizona Parkways. 5 The results of this analysis will assist MCDOT in selecting an appropriate interchange treatment for Arizona Parkway intersections forecast to have high traffic volumes. 5.1 Analysis Method The analysis method used for the assessment of the PGSI is exactly the same method used in the previous MCDOT studies. A PGSI parkway-to-parkway interchange was modeled for a one-hour peak traffic time period using the micro simulation software SimTraffic. Traffic volumes used in the analysis were those used in the previous work representing the uniform capacity volumes for an at-grade parkway-to-parkway intersection. That is to say, traffic volumes on the intersecting parkways essentially were the same and were of a magnitude that resulted in LOS E traffic operations on the atgrade intersection approaches. This was considered a worst case scenario. The uniformity of the volumes requires an equal sharing of the available green time at the intersection, which limits the capacity of each of the intersecting parkways, relative to arterial crossings in which green time allocation favors the parkway approaches. Each of the intersecting parkways was assumed to provide four through lanes of traffic in each direction of travel (Type 8-8) with exclusive turn lanes for right- and left-turns. The SimTraffic model was run five times for the PGSI concept, and the results of the five model runs were averaged to represent the results. The model simulated a single hour of traffic operations and matched the model structure used in the previous work 4 in every way. Traffic signal timing was optimized, using Synchro software for the small network of intersections used in the analysis, to provide optimal traffic operations for the PGSI. The resulting traffic signal timing parameters for the PGSI are provided in Table 5.1. Representation of the PGSI in the SimTraffic model is shown in Figure MCDOT Enhanced Parkway Study, Phase 3, Final Report, prepared for the Maricopa County Department of Transportation, prepared by Morrison-Maierle, Inc., March Final Report, Detail Traffic Operations Analysis of the Parkway Separated Interchange, prepared for Maricopa Department of Transportation and Wilson & Company by Morrison-Maierle, Inc., May 27, Table 5.1 Traffic Signal Timing Assumptions for the PGSI N / S Parkway (1) E / W Parkway (1) Cycle Length Thru/RT Left / U-Turn Thru/RT Left / U-Turn (seconds) (2) Prepared by Wilson & Company, May, Notes: (1) Assumes Michigan Left-Turn with uniform capacity volumes. (2) Green + Change + Clearance Intervals (seconds). Source: Final Report, Detailed Traffic Operations Analysis of the Parkway -Separated Interchange, prepared for Maricopa Department of Transportation (MCDOT) and Wilson & Company by Morrison-Maierle, Inc., May 27, The results of the analysis were summarized to reflect the traffic operations for the overall interchange design and for each traffic movement at the interchange. Primary traffic operations metrics used in the analysis are: delay per vehicle, stops per vehicle, and travel time through the intersection. It should be noted that the analysis included an additional 20 seconds of delay per vehicle to account for the additional time spent by vehicles traveling to and from the U-turn locations in the median of the parkways as part of the indirect left-turn movement. This also is consistent with the previous work for intersections with indirect left-turns. 5.2 Analysis Results The results of the SimTraffic analysis are output in a series of tables and figures developed to show the differences between the PGSI and the SPUI. It is important to note that delay estimates represent system delay associated with travel through the entire interchange. System delay includes traffic signal control delay and other delay associated with travel through the interchange area as estimated by SimTraffic. Table 5.2 provides a comparison of delay and stops associated with the PGSI and SPUI designs aggregated for all traffic movements through the interchange. Table 5.2 Comparison of PGSI and SPUI Interchange Performance Performance Measure Type SPUI PGSI (1) % Difference: SPUI to PGSI Total Delay (hours) Delay per Vehicle (seconds) Total Stops 3,714 3, Stops per Vehicle Total Travel Time (hours) Total Vehicles Entering 11,542 11, Prepared by Wilson & Company, May, Notes: (1) Assumes Michigan Left-Turn with uniform capacity volumes. SPUI = Single Point Urban Interchange PGSI = Parkway - Separated Interchange Source: Final Report, Detailed Traffic Operations Analysis of the Parkway Separated Interchange, prepared for Maricopa Department of Transportation (MCDOT) and Wilson & Company by Morrison-Maierle, Inc., May 27, Page 5-1

37 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 5.1 SimTraffic Representation of PGSI Operations As indicated in Table 5.2: The PGSI is shown to achieve about a 13 percent reduction in total delay and about a ten percent reduction in delay per vehicle; however, the PGSI increases total stops approximately seven percent and stops per vehicle approximately nine percent in comparison to the SPUI. While the results appear to be contradictory, they are in fact consistent. the SPUI design, through vehicles on one of the intersecting parkways do not travel through a traffic signal and, therefore, do not stop. However, the PGSI provides better traffic operations overall, due to the simple twophase traffic signal on each approach to the interchange. Total travel time through the interchange is eight percent higher with the PGSI, which primarily is due to the additional travel time associated with the indirect left-turn movements. Figure 5.2 provides a graphical comparison of the delay per vehicle by movement through the PGSI and the SPUI. Note that there is an additional 20 seconds of delay associated with travel to and from the left-turn median opening downstream of the grade separation. This additional 20 seconds is not traffic signal control delay; it is delay to the left-turn movement associated with interchange design. Also, left-turn delay associated with the PGSI includes delay at the upstream traffic signals, where left-turning vehicles are through movements. Delay at left-turn locations, due to the PGSI traffic signals, is shown in red in Figure 5.2. Delay at traffic signals for right-turn movements in the PGSI is shown in blue. The data in Figure 5.2 indicate that: Control delay (i.e., delay at traffic signals) for the PGSI is the same or lower than the SPUI. This indicates exceptionally good traffic operations at each of the four traffic signals in the interchange. Delay for each through and right-turn movement in the PGSI is very low and is lower than the delay associated with the SPUI. This is particularly interesting, because two of the four through approaches in the SPUI (Northbound Through and Southbound Through) are not delayed by a traffic signal. 6 Traffic signals of the PGSI are operating at a very high level of service for all movements, suggesting the capacity of the PGSI actually is much higher than traffic volume levels assumed for this analysis. Source: SimTraffic analysis results, Wilson & Company, June, Delay shown in Figure 5.2 is attributable to mainline slowing from merging/diverging traffic, not signal delay. Page 5-2

38 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Delay / Veh (sec) Delay / Veh (sec) Figure 5.2 Comparison of Delay Per Vehicle by Movement: PGSI v. SPUI 462 2,154 Parkway / Parkway Delay per Vehicle by Movement PGSI Configuration with MLT Uniform Capacity Volumes 459 2, ,853 Parkway / Parkway Delay per Vehicle by Movement SPUI Configuration with MLT Uniform Capacity Volumes 405 Total Delay = 82 Hours Delay / Vehicle = 26 Seconds Total Stops = 3,973 Stops / Vehicle = 0.35 Total Travel Time = 263 Hours Total Vehicles = 11,488 Total Delay = 94 Hours Delay / Vehicle = 29 Seconds Total Stops = 3,714 Stops / Vehicle = 0.32 Total Travel Time = 244 Hours Total Vehicles = 11, , EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Movement 552 EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR 398 Movement 393 1, , , , Delay by Movement 460 RT lane LT lane Other Delay Hourly Movement Flow Rate (vph) Hourly Movement Flow Rate (vph) Figure 5.3 graphically compares aggregate delay per vehicle by movement for the PGSI and SPUI. Delay per vehicle for left-turn movements in the PGSI is 10 percent greater than that associated with the SPUI; however, the PGSI delay includes the additional 20 seconds in time required to travel to and from downstream left-turn locations. Traffic signal control delay for left-turns in the PGSI actually is lower than traffic signal control delay associated with the SPUI. Aggregate delay per vehicle for through movements in the PGSI is 22 percent lower than that associated with the SPUI. This is particularly meaningful, because two of the four through approaches do not travel through a traffic signal in the SPUI. This indicates that for through vehicles traveling through a traffic signal in the SPUI (1) delay per vehicle is over twice the delay per vehicle as in the PGSI, and (2) PGSI traffic signal operations are very efficient, demonstrating the interchange concept provides a very high capacity. This analysis also indentifies a weakness in the SPUI design, in that the capacity of the signalized portion of the SPUI is far more limited than that of the PGSI. This indicates the PGSI is a better alternative for a condition where both intersecting roadways are very high volume, as would be the case for parkway-to-parkway intersections. Right-turn movements associated with the PGSI design experience 25 percent less delay per vehicle than with the SPUI. Thus, overall, the PGSI results in superior performance. Figure 5.4 graphically compares the aggregate number of stops per vehicle by movement for the PGSI and SPUI. Stops per vehicle are 24 percent greater for left-turn movements in the PGSI than in the SPUI, due to the fact that left-turns in a PGSI must travel through two traffic signals compared to one signal in the SPUI. Through movements associated with the PGSI have the same level of stops per vehicle as in the SPUI, even though one-half of the through movements in the SPUI do not stop for a traffic signal. This indicates very efficient traffic signal operations can be attained with the PGSI design. Right-turn movements in the PGSI and SPUI have the same level of stops per vehicle. Overall, the data indicate a much better level of traffic signal and interchange performance for the PGSI compared to the SPUI. Source: Final Report, Detail Traffic Operations Analysis of the Parkway Separated Interchange, prepared for Maricopa Department of Transportation and Wilson & Company by Morrison-Maierle, Inc., May 27, 2009 Page 5-3

39 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 5.3 Comparison of Aggregate Delay Per Vehicle by Movement Figure 5.4 Comparison of Aggregate Stops Per Vehicle by Movement Delay / Veh (sec) Parkway-Parkway (Mile 6) Aggregate Delay Per Vehicle by Traffic Movement for Each Design Type (MLT Uniform Capacity Volumes) Left-Turn Through Right-Turn Movement Stops / Veh) Parkway-Parkway (Mile 6) Aggregate Stops Per Vehicle by Traffic Movement for Each Design Type (MLT Uniform Capacity Volumes) Left-Turn Through Right-Turn Movement SPUI PGSI SPUI Source: Final Report, Detail Traffic Operations Analysis of the Parkway Separated Interchange, prepared for Maricopa Department of Transportation and Wilson & Company by Morrison-Maierle, Inc., May 27, Preliminary Capacity Estimate For The PGSI An analysis was conducted using microsimulation capabilities of SimTraffic to provide an initial estimate of the general capacity of the PGSI design as a parkway-to-parkway interchange. This analysis was based on traffic operations at the four traffic signals within the interchange. The approach to this analysis was to increase traffic volumes for the through and left-turn movements on both parkways until LOS E traffic operations were achieved. Traffic signal timing was optimized for the analysis and adjusted to achieve LOS E traffic operations for both the through and left-turn movements at each of the four signalized intersections, based on SimTraffic delay per vehicle estimates. This is slightly different than the analysis conducted for comparison of interchange operations, in that it is focused only on delay at the traffic signals and does not include other delay associated with the interchange system. Signalized intersections control the capacity of the interchange. PGSI Source: Final Report, Detail Traffic Operations Analysis of the Parkway Separated Interchange, prepared for Maricopa Department of Transportation and Wilson & Company by Morrison-Maierle, Inc., May 27, 2009 The level of service determination is based on SimTraffic estimates of traffic signal delay per vehicle using the 2000 Highway Capacity Manual (HCM) relationship between LOS and delay per vehicle. This approach is similar to using the 2000 HCM approach to analyze signalized intersection capacity, except the delay per vehicle is estimated using microsimulation instead of the deterministic methodology contained in the 2000 HCM. A refined 90-second traffic signal cycle 7 was selected to maintain consistency along the corridor for traffic progression. Traffic signal splits for capacity analysis at the interchange were: Through/Right Movement approximately 64 seconds Left-Turn/U-turn Movement 26 seconds. 7 The traffic signal cycle in this analysis was tested in a range from 80 to 100 seconds to determine a sensitivity to intersection LOS. It was determined that a constant cycle length throughout the corridor reduced the sensitivity to changes in LOS and that a cycle length of 80-90s is appropriate for parkway corridor. Page 5-4

40 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Five simulations were conducted, and the results were averaged. Figure 5.5 provides a summary of the average delay per vehicle by movement for the PGSI and the average traffic volume of each movement derived from the five simulations. Figure 5.5 PGSI Delay Per Vehicle and Traffic Volume by Movement for Estimating Interchange Capacity Delay / Veh (sec) Parkway / Parkway Delay per Vehicle by Movement PGSI Configuration with PGSI Uniform Capacity Volumes (90 Sec Cycle) Total Delay = 314 Hours Delay / Vehicle = 57 Seconds Total Stops = 23,275 Stops / Vehicle = 1.18 Total Travel Time = 700 Hours Total Vehicles = 19, , , , , EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR Movement Source: Final Report, Detail Traffic Operations Analysis of the Parkway Separated Interchange, prepared for Maricopa Department of Transportation and Wilson & Company by Morrison-Maierle, Inc., May 27, 2009 The results indicate: Signalized intersections at the interchange operate very efficiently and support a very high traffic throughput. Results from the previous work suggest parkway capacity is higher at parkway-to-arterial intersections than at at-grade parkway-to-parkway intersections. This makes sense in that green time and, therefore, demand at at-grade parkway-to-parkway intersections generally would be more evenly distributed between the two parkways, resulting in a lower capacity for each parkway. Through vehicle capacity on the parkway at a PGSI is estimated to be on the order of 1,000 to 1,050 vehicles per hour per lane. This is consistent with, and slightly higher than, the 674 Other Delay RT lane LT lane Hourly Movement Flow Rate (vph) results for the parkway analyses that were achieved at parkway-to-arterial intersections in the previous work conducted for the MCDOT Enhanced Parkway Studies. The three parkway-to-parkway intersection designs at-grade, SPUI, and diamond interchange have associated capacity constraints along the corridor for at least one of the parkways. The PGSI presents a lesser constraint on corridor capacity, as this interchange design should provide through vehicle capacity that equals or exceeds the ability of the upstream intersections to deliver vehicles to the interchange. The capacity of left-turn lanes in the PGSI is directly dependent on the opposing through traffic demand and corresponding green time allocation. In this analysis, the green time for left-turns far exceeds the typical green time available for left-turns at an at-grade intersection; so, the per-lane capacity should exceed that of typical left-turn lanes. Simulation results indicate a minimum left-turn lane capacity of approximately 300 vehicles per hour per lane, based on traffic volume and signal timing assumptions used in the analysis. Left-turn capacity could be significantly higher, if the opposing through-movement traffic demand is less than capacity. In this case, more green time could be allocated to the left-turn movement. 5.4 Detailed Analysis Conclusions The following conclusions are based on the detailed traffic operations analysis of the PGSI design: The conceptualized PGSI appears to provide a very high-capacity interchange well suited for high-volume parkway-to-parkway intersections. The PGSI provides very good levels of service for all traffic movements under the traffic volume and interchange geometry assumptions used in this study for comparison to the SPUI. The PGSI is particularly well suited for situations where both intersecting parkways have very high traffic volumes; but, the design could be applied in virtually any situation, where the intersection of the two parkways had four approaches. The overall capacity of the PGSI is greater than that of a comparable SPUI, because traffic signal operation is more efficient. The capacity for left-turns in the PGSI configuration is much greater than that of the SPUI with the same number of left-turn lanes on each approach, because of its simple two phase signalization. The SPUI must rely on three-phase signalization, which is much less efficient. The primary weakness of the SPUI in comparison to the PGSI is the lower capacity for accommodating left-turn movements. Based on traffic volume levels assumed for this study, through-lane capacity of the PGSI is estimated to be on the order of 1,000 to 1,050 vehicles per hour per lane. Based on traffic volume levels assumed for this study, left-turn lane capacity of the PGSI appears to be on the order of a minimum of 300 vehicles per hour per lane. dual left-turn lanes, left-turn capacity of the PGSI would be on the order of a minimum of 600 vehicles per hour per approach. This assumes through lanes are operating at capacity. Page 5-5

41 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study The primary strength of the PGSI is that it is a high-volume interchange that treats each approach in the same manner, as opposed to the SPUI and diamond interchange which favor a dominant through movement on the highest volume roadway. The SPUI and diamond interchange tend to break down when traffic volumes grow on the cross street that passes through the signalized intersection. This is less of an issue with the PGSI design. the PGSI, capacity should equal or exceed the capacity of the upstream intersections to deliver traffic to the interchange on both parkways. Thus, this parkway-to-parkway intersection design generally would not be the capacity constraint along a corridor, as might happen with other signalized interchange designs. Page 5-6

42 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study 6 Findings and Recommendations The intent of the Arizona Parkway /Interchange Operational Analysis and Design Concepts Study was to evaluate forecast average daily traffic volumes on the Arizona Parkway network and identify: The number of lanes required for each segment of the Arizona Parkway system, where a segment is defined as a connection between two major facilities in the Maricopa County roadway network (including all other jurisdictions in the study area); The number of intersections created by the crossing of two parkway facilities, i.e., parkway-to-parkway intersections, and whether or not these intersections would require flaring or added lanes on the intersection approach to accommodate forecast entering volumes; The number of required parkway-to-parkway grade-separated intersections, due to the inability of an at-grade intersection with a given number of lanes to accommodate entering volumes; The interchange types for each grade-separated intersection location and the most suitable interchange design for the parkway system; and The amount of R/W necessary to preserve, where grade-separated interchanges are required, in addition to the 200-foot R/W identified in the Design Guideline Recommendations for the Arizona Parkway. The results of the study are summarized in the following sections. 6.1 Segment Capacities and Required Number of s for the Arizona Parkway Network Capacity thresholds initially were used to define the number of lanes required for each parkway segment, based on the forecasted daily traffic volume on a given parkway segment. The Arizona Parkway network capacities for LOS E are presented in Table 6.1. Table 6.1 Arizona Parkway Level of Service Threshold Application of the capacity thresholds was a good starting point for ultimately smoothing out the parkway segments into their ultimate configurations. Smoothing of the parkway segments occurred during TAC meetings; representatives from participating jurisdictions provided input regarding expected development for any given roadway segment. The intent of the smoothing was to eliminate parkway segments that were not consistent in cross-section, i.e., forecast traffic volumes indicated a need along the length of the parkway that may have varied in width from six lanes to eight lanes and back to six lanes. Figure 6.1 shows the recommended number of lanes for each parkway segment and parkway-to-parkway intersection in the study area. 6.2 At- s Of the 62 intersections identified in the study area, two intersections (#53 and #55) were dropped from further evaluation during this study. These intersections were part of the proposed parkway system at the beginning of the study. However, analyses associated with the ongoing Hidden Valley Study and review of analyses findings by funding partners and stakeholders resulted in elimination of the parkway between these two intersections. It is important to note that, although the two intersections were eliminated, the original numbering system for study area intersections was retained to avoid confusion. configurations at the 60 remaining intersections were evaluated based on entering volume thresholds, as documented previously in Tables Results indicated that 47 of the remaining 60 intersections could be constructed at-grade, consistent with the Arizona Parkway indirect left-turn intersection design established in Design Guideline Recommendations for the Arizona Parkway. The typical Arizona Parkway cross-section would provide sufficient capacity given the forecast traffic volumes entering these intersections. lane configurations were then compared to the recommended number of lanes for each parkway segment documented previously in Table 2.2. Locations were identified where the recommended lanes from Table 2.2 were fewer than those required to accommodate intersection entering volumes from Tables These intersections are listed below in Table 6.2. The number of lanes at each parkway-to-parkway intersection shown in Figure 6.1 will match the segment number of lanes at all locations except these four intersections. At these locations, the number of lanes identified for the intersection reflects the flaring to increase the number of lanes to accommodate intersection entering volumes. Daily Traffic Total Number of s (vehicles per day) (1) LOS E (2) 4 49,400 vpd 6 74,100 vpd 8 98,800 vpd Notes: (1) Assumes a K = 0.075; balanced green time allocation per lane at high volume parkway-to-parkway intersections. (2) Assumes a capacity of 950 vehicles per hour (vph) per approach lane and a peak-hour factor (PHF) of 1.0. LOS = Level of Service Source: Wilson & Company and Morrison-Maierle, Inc., October Page 6-1

43 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study ID # Entering Volume 1 Table 6.2 Flared Parkway-to-Parkway s Assumed Mainline Configuration 2 Maximum Entering Threshold Volume 3 Verification Proposed s Daily Threshold Volume Verification 5 145, ,000 ADD LANES ,000 < Threshold , ,000 ADD LANES ,000 < Threshold , ,000 ADD LANES ,000 < Threshold , ,000 ADD LANES ,000 < Threshold Prepared by: Wilson & Company, NOTES: 1) Sum of approach leg volumes from MAG model data (see source). 2) Mainline lane assumption based on Arizona Parkway theoretical mainline capacity: 0 0 = Mainline Crossing Roadway. 3) ADT threshold volume revised ) Though entering volumes exceed the capacity threshold, supplemental analysis indicated that the proposed lane configuration provides acceptable intersection operations Tan shading identifies the proposed lane configuration required to satisfy intersection entering volume. Source: Hidden Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), MAG, 9/30/2008. Hassayampa Valley Buildout Volumes on Framework Network (both Hidden and Hassayampa Frameworks), 9/30/ Separated Interchanges Of the 60 parkway-to-parkway intersections in the study area carried forward to full evaluation, 13 will require grade separation to accommodate high entering volumes on all approaches. In most cases, these intersections can be accommodated with typical interchange designs, such as a standard diamond, a SPUI, or a DDI. However, these interchange designs are not consistent with the Arizona Parkway concept, which incorporates indirect left-turn movements. The indirect left-turn intersection operates on a two-phase signal and, therefore, offers more efficient traffic progression and turning movements through quarter-mile increments. A determination was made during this study that an interchange design that maintains consistency with the Arizona Parkway s efficient and unique operating concept would be preferred. Therefore, a new interchange was developed and evaluated. The PGSI, introduced earlier, concept was developed and tested for its effectiveness with respect to the indirect left-turn movement and the two-phase signal operation of the Arizona Parkway. Traffic simulations supported the conclusion that the PGSI will provide efficient and high-capacity functionality. It also is adaptable to the different intersection configurations and, therefore, will fully support the capacity requirements of the parkway system. The PGSI provides the capacity necessary for all except two of the 13 intersections requiring grade separation. At these two locations s #23 and #61 directional travel volumes are expected to exceed the capacity of the left-turn phasing embedded in the PGSI. At #23 Sun Valley Parkway/Bell Road at Jackrabbit Trail Parkway, a high volume of eastbound to southbound and northbound to westbound turning movements are forecast. At #61 Hidden Waters Parkway at Watermelon Parkway, a high volume of southbound to westbound and eastbound to northbound turning movements are forecast. Thus, these locations (given a special symbol in Figure 6.1) will require direct connector and flyover ramps to accommodate high turning-movement volumes. It was concluded that the PGSI can support the higher capacity of the Arizona Parkway network more effectively than the other interchange types. And, as noted above, the operation of this interchange maintains a consistent driving experience by incorporating the left-turn subsequent to passing through the intersection. Although each intersection needs to be evaluated in detail during the DCR stage of roadway development, it is recommended that the PGSI design solution be implemented at all grade-separated parkway-to-parkway intersections to satisfy Buildout traffic conditions (Table 6.3). The PGSI can only be an interim solution for s #23 and #61, where direct connector and flyover ramps ultimately will be required to accommodate high directional travel demand. Table 6.3 Recommended -Separated Interchange Type by Parkway-to-Parkway ID # Interim (through 2030) Ultimate (beyond 2030) 6 PGSI PGSI 7 PGSI PGSI 9 a PGSI PGSI 19 PGSI PGSI 23 PGSI PGSI w/ EB-SB Direct Connector and NB-WB Flyover Ramps 38 PGSI PGSI 39 PGSI PGSI 45 PGSI PGSI 46 b PGSI PGSI 48 PGSI PGSI 49 PGSI PGSI 50 c PGSI PGSI 51 d PGSI PGSI 61 PGSI PGSI w/ EB-NB Flyover and SB-WB Direct Connector Ramps Notes: (a) Recommendations at this intersection based on the US-60/Grande Avenue Access Management Plan: SR-303L/Estrella Freeway to SR-74. (b) This intersection will be have a T configuration, as the City of Goodyear does not plan to construct Yuma Road as a Parkway facility east of Perryville Road. (c) This intersection will be have a T configuration, as the City of Buckeye does not plan to construct Southern Avenue Parkway facility between Sr-85 and Watson Road. Additional analysis of this intersection/interchange will be required during future studies. (d) This intersection will be have a T configuration, as the City of Goodyear does not plan to construct a facility east of Perryville Road. Additional analysis of this intersection/interchange will be required during future studies. Source: Wilson & Company, 4/27/2009. Page 6-2

44 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study 6.4 Right-of-Way Preservation Recommendations The 200-foot R/W preservation requirement associated with the standard Arizona Parkway cross-section is adequate to meet the needs of at-grade parkway-to-parkway intersections up to eight lanes on each approach. However, additional R/W will need to be preserved at parkway-to-parkway intersections requiring grade separation, as grade separation involves development of directional ramps and satisfaction of vertical clearances to effect safe crossing of one parkway over the other. As noted previously, typical interchanges developed within the County (standard diamond, SPUI, and DDI) require from 19 to 30 acres of additional R/W, if employed at the intersection of two 8-lane parkways. The PGSI will require approximately 15 acres of additional R/W to accommodate the intersection of two 8-lane parkways. This estimate is based on a rough diamond shape centered on the intersection location (Figure 6.2). The R/W estimate of 15 acres assumes a generally flat intersection location and typical layout conditions, i.e., there are few major natural or man-made physical features requiring modifications to the typical design. Thus, R/W needs may increase given the presence of special conditions, such as canals, utilities, railroads, adjacent roads, and adjacent land uses. Page 6-3

45 Arizona Parkway /Interchange - Operational Analysis and Design Concepts Study Figure 6.1 Arizona Parkway Network Recommendations Page 6-4