Corpus Christi Metropolitan Planning Organization Regional Travel Speed Study Flynn Parkway, Suite 404 Corpus Christi, TX 78411

Transcription

1 Corpus Christi Metropolitan Planning Organization 2006 Regional Travel Speed Study Prepared for: Corpus Christi Metropolitan Planning Organization 5151 Flynn Parkway, Suite 404 Corpus Christi, TX Prepared by: 7950 Elmbrook Drive Dallas, Texas August 06, 2007 Project Number

2 Table of Contents Page No. 1.0 Executive Summary Study Purpose Study Method Introduction Congestion Management Process Methodology Corpus Christi MPO CMS/CMP Policy SAFETEA-LU CMP Requirements Corpus Christi MPO CMS/CMP Policy Changes Methodology Assumptions Definitions and Data Dictionary Route Selection Project Methodology Data Collection Equipment and Training Procedure Data Monitoring and Quality Control Data Analysis Data Aggregation Speeds and Travel Times Travel Speeds Stop Delay Congestion Index Congestion Mitigation Plan...23 i

3 List of Tables Page No. Table 1 - Glossary...4 Table 2 Top 10 Segments With Largest Drop in Performance Relative to Table 3 Top 10 Segments With Largest Improvement in Performance Relative to Table 4 Top 15 Worst Segments By Congestion Index in List of Figures Page No. Figure 1 Intersections and Routes 5 Figure 2 Posted Speed Limits..8 Figure 3 School Zones.9 Figure 4 Intersection Segments..10 Figure 5 AM Average Speed..13 Figure 6 PM Average Speed...14 Figure 7 AM Congestion Index..15 Figure 8 PM Congestion Index...16 Figure 9 AM Percent Change In Congestion Index From Figure 10 PM Percent Change In Congestion Index From ii

4 1.0 Executive Summary 1.1 Study Purpose It is necessary for metropolitan planning organizations (MPO) to maintain an accurate, up to date regional transportation model in order to conform with State and Federal regulations for air quality and transportation projects. MPO s update and calibrate their models using current information on the roadway network, area development, and other relevant characteristics such as travel time and speed data. The primary purpose of the 2006 Travel Speed Study is to evaluate the transportation system and prepare a report as part of the Congestion Management Process in compliance with the SAFETEA-LU requirements. The secondary purpose of the study was to identify trends in congestion and travel time in order to identify problem locations for possible improvements. 1.2 Study Method The 2006 Travel Speed Study was conducted with enhancements to the required elements to the data collection, data management, and analytical methods. The roadways were mapped to establish centerlines and record relevant roadway features. Features located in the mapping process included: speed limits, school zones limits, and intersection control. Travel speed data was collected during the months of September and October 2006 on Tuesdays, Wednesdays, and Thursdays, during the morning and during the afternoon peak period as follows: Morning Peak Period: 7:00 AM to 9:00 AM Afternoon Peak Period: 4:00 PM to 6:00 PM Travel time runs were conducted using the floating car method. Roadways included arterials and freeways. There were a total of 6 runs in each direction (3 in each direction in the AM/PM peak) on each roadway included in the study. The data collection process took two months. Intersection delay for through vehicles was recorded at signalized intersections and compared with criteria in the Highway Capacity Manual to determine level of service. In order to differentiate between congested roadways and roadways with low speed limits, a method for illustrating the data was incorporated into the 2006 Travel Speed Study. This method uses a ratio of actual travel speed to posted speed limit and is referred to as the Congestion Index (CI). 1

5 2.0 Introduction It is necessary for Metropolitan Planning Organizations (MPO) to maintain an accurate, up to date regional transportation model in order to conform with State and Federal regulations for air quality and transportation projects. MPO s update and calibrate their models using current information on the roadway network, area development, and other relevant characteristics. The MPO updates their travel time and speed data periodically. The primary purpose of this year s 2006 Travel Speed Study was to expand on the 2003 effort to cover more of the network and to develop a trend for those previously included. The area encompassed by the Corpus Christi MPO is currently within air quality attainment levels. For this 2006 study, the MPO contracted with Carter & Burgess to collect roadway characteristics and field-measured travel time and speed data for use in calibrating and validating the regional transportation model. However, in addition to collecting this vital information, Carter & Burgess was able to expand the scope of the study without increasing the cost to include a larger sample of roadways, a major GIS enhancement, digital video, percent stops at intersections, and congestion index (% of posted speed). Through the methodology developed and the additional data assembled, the data collected in this study has a variety of additional uses. Because the information is all housed in the GIS system, queries can group data by area for use in individual planning processes. The database can be used for background information for signal timing projects, signing and pavement marking projects, school zone issues, and other transportation related projects. The following report describes the 2006 Travel Speed Study. Section 3 focuses on the methodology and includes a set of assumptions and caveats, definitions for terms used throughout the report, and the process used to actually collect and manipulate the travel speed data. Information is provided regarding quality control, data analysis, data aggregation, and problems encountered during the data collection process. Section 4 documents the results of the data collection showing various aggregations. 2

6 3.0 Congestion Management Process Methodology 3.1 Corpus Christi MPO CMS/CMP Policy The current Corpus Christ MPO Policy is included for reference. 3.2 SAFTETEA-LU CMP Requirements The majority of the changes in the current CMP requirements are very cosmetic with reference to those included in TEA-21. The changes were essentially to place more emphasis on management and operations to mitigate congestion before adding capacity. This is a restatement of the original intent but more direct this time to better integrate the CMP and planning process. 3.3 Corpus Christi MPO CMS/CMP Policy Changes The current policy as authored by the MPO is in compliance with the SAFETEA-LU requirements. The only suggested change would be to update the language to reference the Congestion Management Process and no longer the Congestion Management System. 3

7 4.0 Methodology 4.1 Assumptions Several assumptions have been made in order to conduct the study. These assumptions are stated below along with a few caveats to aid in interpretation of the data. The morning and afternoon peak periods are 7:00 AM to 9:00 AM and 4:00 PM to 6:00 PM for all roadways that were included in the study. The percent stops are an indicator of the travel time consistency. The differentially corrected GPS 1-second points with 10-foot accuracy are adequate for study purposes. Test vehicles traveled with the flow of traffic, where traffic was present; however, if traffic was not present, the test vehicles maintained the speed limit. 4.2 Definitions and Data Dictionary Several terms are used throughout this report and are defined here for clarification. Table 1 - Glossary Term Afternoon Peak Period Percent Stops Congestion Index Approach Delay Theoretical Travel Time Free Flow Speed Mean Running Speed Mean Travel Speed Morning Peak Period Space Mean Speed Spot Speed Time Mean Speed Peak Period Definition The time period from 4:00 PM to 6:00 PM on a typical weekday Percent of runs in which the driver was forced to stop on the segments The ratio of the actual speed to the posted speed limit. Segment travel time minus the theoretical travel time at posted speed Time it takes for a vehicle to travel a given section of roadway at the posted speed limit. Speed Limit or weighted average speed limit. Weighted by length of speed zones where the speed limit changes between intersections. Speed calculate from the time the vehicle is traveling at > 3 MPH The distance divided by the mean travel time of several trips. The time period from 7:00 AM to 9:00 AM on a typical weekday Speed calculated from the distance traveled over the time to travel that distance The instantaneous measure of speed at a specific location on a roadway. The arithmetic average of 1-second GPS speed within the segment. AM or PM Study Period 4

8 4.3 Route Selection The 2006 study included all arterials and freeways within the study area. All signalized intersections on these routes were included in the study for delay calculations as well. The included routes and intersections are shown in Figure Project Methodology The 2006 Travel Speed Study included enhancements to the data collection, data management, and analytical methods. First, the roadways were mapped to establish centerlines and record relevant roadway features. The Carter & Burgess geographic information system (GIS) utilizes a linear reference system (LRS) for the basis of all roadway and travel speed data. Features and data within a linear reference system use position along a route instead of a x,y coordinate system. The route features contain measures or distance along the route. After mapping all routes, the travel time runs were collected. The 2006 Study used both GPS equipment and digital video for a thorough analysis. The travel time studies were completed using test vehicles, each fully equipped with GPS equipment and one trained technician. Intersection delay, because data was recorded every one second using GPS equipment, was calculated for all signalized intersections within the study area. Delay calculations were provided for through vehicles only. No analyses were conducted for turning movements. The delay in seconds was then compared with the Highway Capacity Manual criteria for level of service for approaches to signalized intersections. These criteria categorize vehicle delay into levels of service ranging from LOS A, meaning less than or equal to 10 seconds delay, to LOS F, meaning more than 80 seconds of delay. The intersections with poor levels of service (i.e. long delay) were marked and illustrated in the GIS system. Summarizing the results purely by average speed may indicate slow speeds when in reality, traffic may be traveling according to a low posted speed limit. In order to differentiate between congested roadways and roadways with low speed limits, a method for illustrating the data that was introduced in 2003 was once again used in the 2006 Travel Speed Study. This method uses a ratio of actual travel speed to posted speed limit called the Congestion Index (CI). A CI of 1.0 or greater indicates free flow speed, where traffic is traveling at the speed limit or higher. Municipalities can define levels of CI to indicate free flow, average flow, and congested flow. This information can be used in the planning process to better appropriate funds for needed improvements. 5

9 Figure 1 Intersections and Routes 6

10 4.5 Data Collection Equipment and Training Mapping was conducted using a Trimble PRO-XRS GPS unit with real-time differentially corrected data and sub-meter accuracy. The GPS unit was attached to a test vehicle and roadway features were coded using software on a laptop computer. Travel time runs were conducted using Bluetooth enabled state of the art GPS units. These units are significantly less expensive than the Trimble PRO-XRS and provide accuracy to 10-feet. The GPS data was collected and stored on PDA s. The technicians were well trained prior to initiating the travel time runs. Project and task managers from Carter & Burgess provided the training to the technicians and the data collection supervisors. The Carter & Burgess managers have significant experience both with this type of study and with the equipment used. The Carter & Burgess managers trained and rode with technicians on example routes. The training occurred over two days, and each technician was tested by the managers before being permitted to work on the project. Training consisted of an overview of the project, the equipment being used, the floating car method for travel time runs, and safety. The global positioning system (GPS) uses multiple satellites to triangulate position. Four satellites are required for an accurate reading Procedure The first step in the study process was to map the roadways using GPS equipment to establish centerlines and code relevant roadway features. Centerlines were mapped by driving in one direction and using an offset distance from the travel lane to code the centerline. Features documented in the mapping process included: speed limits, school zones limits, intersection control, and construction areas. The speed limits and school zone speed limits were used to calculate the Congestion Index to determine whether roadway segments were congested, intersection control was collected to supplement the GIS system, and construction areas were noted so that low speeds in these areas could be filtered. This data greatly enhanced the MPO s existing GIS system. Upon completion of the mapping, the travel time runs were collected. The equipment automatically collected location and time data every 1-second. This information was used to calculate speeds and travel times. Figures 2 and 3 (Posted Speed Limit and School Zones) illustrate the various elements coded during the mapping process or supplemented using models provided by the MPO. For the 2006 Travel Speed Study, data was collected during the months of September and October The data was collected on Tuesdays, Wednesdays, and Thursdays, during the morning and afternoon peak periods. Runs were conducted on 7

11 Monday afternoon through Friday mornings because they more consistently represent average conditions. The study time periods were as follows: Morning Peak Period: 7:00 AM to 9:00 AM Afternoon Peak Period: 4:00 PM to 6:00 PM Travel time runs were conducted using the floating car method. The floating car method is described in detail in the Manual of Traffic Engineering Studies published by the Institute of Transportation Engineers. The test vehicle travels within the flow of traffic, passing as many vehicles as pass the test vehicle. In this way, the test vehicle is representing the average vehicle. Travel time runs were conducted on 310 centerline miles of routes along all arterials and freeways. As shown in Figure 4, the roadways were broken down into 998 directional segments and 6 runs were made on each segment, including 3 runs in each direction during the morning peak and 3 runs in each direction during the afternoon peak, resulting in over 3,720 miles of travel time runs. When the runs were completed, a statistical analysis was performed to determine the resulting confidence level and error of the data. 8

12 Figure 2 Posted Speed Limits 9

13 Figure 3 School Zones 10

14 Figure 4 Intersection Segments 11

15 4.6 Data Monitoring and Quality Control The centerline mapping and travel time runs produced an enormous amount of data. The position information was differentially corrected using an established base station in Corpus Christi to bring the accuracy from 50 feet to 10 feet. This corrects any errors that may have occurred in the satellite readings. These files were then exported into a shape file for viewing in GIS. 4.7 Data Analysis The data analysis includes various levels of review, including automated QAQC, and manual QAQC. Many of the primary steps taken to process the large amounts of data are shown below. Assign segments for aggregation purposes o intersection segment o speed limit o school zone speed (if applicable) Calculate average Space Mean Speed and Time Mean Speed. Calculate frequency of stops within each segment Calculate the stop delay as the count of one second GPS points where the speed <=3 MPH Calculate the segment delay as the difference between travel time and free flow travel time. Calculate travel time Calculate free flow travel time Average by intersection segment 4.8 Data Aggregation The summary data has been aggregated on various levels. Data can be viewed from levels as detailed as the raw 1-second point data to the intersection segments. This allows the data to be presented in various forms depending on the audience. 12

16 Speeds and Travel Times There was a large amount of data collected for the 2006 Travel Speed Study. The easiest way to present and assimilate the information is in tables, charts, and graphics. This section presents the results of the study in visual format, allowing the reader to reach individual judgments at their discretion, and offering summary conclusions only, by section. The following sections display the resulting speed for the 310-centerline miles of roadway included in the study. This section displays all information collected for this study for evaluation, interpretation, and use in developing and prioritizing future projects. 5.1 Travel Speeds Figures 5 and 6 summarize the data for each of the time periods. 5.2 Stop Delay Stop Delay is one element that is no longer recognized by the Highway Capacity Manual. But, for comparison purposes, it was calculated and defined as the point that the vehicle speed is reduced to 3 mph. 5.3 Congestion Index Figures 7 and 8 include the summary data for congestion index. Using the mapping effort and subsequent linear reference system that was developed, the Congestion Index (% of posted speed) was calculated to represent the delay encountered. Figures 9 and 10 show the percentage change of congestion index compared to the 2003 historic values. Tables 2 and 3 list the segments with greatest changes since 2003 based on congestion index. Table 4 shows the worst segments in 2006 by congestion index. These summaries have been filtered to include those segments with true congestion and not impacted by construction, school zones, or short segment length. 13

17 Figure 5 AM Average Speed 14

18 Figure 6 PM Average Speed 15

19 Figure 7 AM Congestion Index 16

20 Figure 8 PM Congestion Index 17

21 Figure 9 AM Percent Change In Congestion Index From

22 Figure 10 PM Percent Change In Congestion Index From

23 July 2007 Table 2 Top 10 Segments With Largest Drop in Performance Relative to 2003 Route ID Route Name IntersectionSegment Peak Period 2006 Congestion Index (CI) 2006 Avg Speed 2006 Weighted Speed Limit 2003 Congestion Index (CI) 2003 Avg Speed 2003 Weighte d Speed Limit YORKTOWN - Bill Witt Park TO WB Cimarron PM % EVERHART - SB Burney TO McArdle PM % STAPLES - SB/WB HEB TO Williams PM % LEOPARD - Wood River TO FM 1889 EB / Trinity River AM % EVERHART - SB Bonner TO Holly PM % STAPLES - Autotown/Gollihar TO EB/NB Everhart AM % LEOPARD - EB Starlite TO McKinzie AM % KOSTORYZ - SB Brower TO Horne PM % STAPLES - SB/WB Gollihar TO Everhart PM % STAPLES SB/WB SPID EBFR TO HEB PM % Note: Short Segments (< 500ft) and segments containing school zones have not been considered for this table CI Change % 20

24 July 2007 Table 3 Top 10 Segments With Largest Improvement in Performance Relative to 2003 Route ID Route Name IntersectionSegment Peak Period 2006 Congestion Index (CI) 2006 Avg Speed 2006 Weighted Speed Limit 2003 Congestion Index (CI) 2003 Avg Speed 2003 Weighted Speed Limit 4029 AYERS - SB Port TO Gollihar AM % STAPLES - SPID WBFR TO 4022 EB/NB McArdle PM % LEOPARD - Wood River TO FM 4041 EB 1889 / Trinity River PM % LEOPARD EB Lantana TO SPID EBFR PM % ENNIS 4055 JOSLIN - SB Alameda TO Nile PM % 4030 AYERS - NB Port TO Horne AM % STAPLES EB/NB HEB TO SPID EBFR PM % OCEAN/SHOR 4011 ELINE - EB Peoples TO Lawerence PM % McArdle TO SPID 4029 AYERS - SB WBFR PM % SARATOGA - Long Meadow TO 4004 WB Everhart PM % *Note: Short Segments (< 500ft) and segments containing school zones have not been considered for this table CI Change % 21

25 July 2007 Table 4 Top 15 Worst Segments By Congestion Index in 2006 RouteID Route Name Intersection Segment STAPLES SB/WB McArdle TO SPID WBFR PM STAPLES SB/WB Gollihar TO Everhart PM Peak Period 2006 Congestion Index 2006 Average Speed 4014 WALDRON - NB 4041 LEOPARD - EB Wood River TO FM 1889 / Trinity River AM YORKTOWN - WB Bill Witt Park TO Cimarron PM HOLLY - WB Ayers TO SH 286 NB PM IH 37 - EB Water TO Shoreline AM HOLLY - EB SH 286 NB TO Ayers AM Weighted Speed Limt Flour Bluff/HIGH SCHOOL TO Hustlin Hornet AM STAPLES - SB/WB SPID EBFR TO HEB PM STAPLES - EB/NB Autotown/Gollihar TO Everhart AM AIRLINE - SB McArdle TO SPID WBFR PM KOSTORYZ - NB Sunnybrook TO Gollihar PM STAPLES - EB/NB Firestation TO Holly PM STAPLES - SB/WB HEB TO Williams PM STAPLES - EB/NB Annapolis TO Kosar PM Note: Short Segments (< 500ft) and segments containing school zones have not been considered for this table 22

26 6.0 Congestion Mitigation Plan In line with the encouragement shown in the SAFETEA-LU requirements, operations and management are key to cost effectively managing congestion especially along arterial corridors. The majority of the arterial corridors would benefit from a system wide signal timing review. In some cases this will bring the corridor to an acceptable LOS for an extended period while others will buy the MPO some time before adding capacity depending on future growth patterns. As development or redevelopment occurs, it is recommended that local Traffic Impact Analyses (TIA) be completed to recommend what is necessary to maintain an acceptable level of service. This was done at the request of the MPO for the Terra Mar development at Holly and Ennis Joslin. The analysis will commonly use Synchro to evaluate arterial conditions and then the Texas MUTCD for evaluating the warrants for possible signalization. The inputs to this type of analysis include various field characteristics as well as general assumptions such as: 1. Speed Limit on Holly Rd -40 mph 2. Number of Lanes on Holly Rd -1 Lane 3. Number of Lanes on Ennis Joslin-1 Lane 4. Holly Rd is major and northbound Ennis Joslin is assumed as minor street 5. Traffic Growth Rate-3% 6. Peak Hour Traffic-10% of ADT 7. 50% of generated traffic by residential development between Holly Rd and Wooldridge will use Holly Rd and 50% will use Wooldridge 8. It was also assumed that traffic conditions and pattern will not change with the construction of new roads 9. ADT on Holly Street-7490 vehicles per day (2005) 10. Projected ADT on Holly Rd -7490x(1.03) 5 =8683 vehicles per day (2010) 11. Projected Peak Hour Traffic-8683x0.10=868 vehicles per hour 12. Trip rate per lot-1 vehicular trip during peak hour 13. Number of Lots in the area between Holly Rd and Wooldridge Generated Trips-675 vehicular trips during peak hour 15. Generated Trips-338 vehicular trips during peak hour using northbound Ennis Joslin Based on these details, the intersection was evaluated for a signal warrant. In light of the limited detail currently available for this development, the number of warrants analyzed included only Warrant 3 for the Peak Hour. Warrant 1-Eight-Hour Vehicular Volume (Not Considered) Warrant 2-Four-Hour Vehicular Volume (Not Considered) Warrant 3-Peak Hour (possibly meet this warrant) Warrant 4-Pedestrian Volume (Not Considered) Warrant 5-School Crossing (Not Considered) Warrant 6-Coordinated Signal System (Not Considered) Warrant 7-Crash Experience (Not Applicable) 23

27 Warrant 8-Roadway Network (Not Considered) A detailed traffic impact analysis, site visit, and traffic data collection would be required to fully analyze the remaining signal warrants and to come up with a definite conclusion. Warrant 1 and 2 are usually considered strong warrants and they need to be evaluated fully before a recommendation is made. Elements that may be included in a full analysis would include how the traffic patterns or travel behavior might change due the improvements in the surrounding road network and account for the passer-by trips depending on the development type. 24