I 95 EXPRESS LANES SOUTHERN TERMINUS EXTENSION TRAFFIC OPERATIONS AND SAFETY ANALYSIS REPORT

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2 I 95 EXPRESS LANES SOUTHERN TERMINUS EXTENSION TRAFFIC OPERATIONS AND SAFETY ANALYSIS REPORT February 2016

3 INTERSTATE 95 EXPRESS LANES SOUTHERN TERMINUS EXTENSION PROJECT Commonwealth of Virginia Virginia State Project Number , C501 UPC # Traffic Operations & Safety Analysis Report Interstate Project This document has been prepared and submitted to obtain FHWA approval to modify existing Express Lanes terminus ramps on a fully controlled interstate highway. Submitted by: This study has been reviewed by the Northern Virginia Mega Projects team and District Traffic Engineering department and they concur with the findings. The request for reconfiguration of the interstate access points is approved for engineering and operational acceptability. Tarsem Lal, P.E. Senior Major Projects Engineer Federal Highway Administration, Virginia Division Susan Shaw, P.E. Regional Transportation Program Director Virginia Department of Transportation Date of Approval Date of Approval 2

4 I 95 Express Lanes Southern Terminus Traffic Operations Analysis Report Contents 1 Project Background Purpose and Need Study Area Project Location Map Study Area Boundaries and Facilities Included Screening of Alternatives Proposed Action in the Preferred Build Alternative Existing Conditions Existing Road Geometry & Access Locations Existing Operational & Safety Conditions Alternatives Considered Alternative Development and Previous Work Transportation Systems Management (TSM) Options No Build Alternative Refinement of Preferred Build Alternative Traffic Volume Projections Traffic Analysis Years Traffic Data Collection Traffic Operations Analyses Methodology Microsimulation Analyses Existing Conditions Calibration Existing Conditions Analysis Findings Existing Conditions Summary of Findings I 95 Northbound AM Peak Hour Alternatives Analyses I 95 Southbound PM Peak Hour Alternatives Analyses I 95 Southbound PM Peak Hour Summary and Preferred Alternative Safety Analyses Data Collection & Analysis Methodology... 50

5 10.2 Historical Crash Frequency Crash summary before and after Express Lanes Summary Environmental Compliance Summary of Findings Traffic Operational Analysis Findings Safety Analysis Findings... 54

6 1 Project Background Interstate 95 (I 95) serves as a major corridor for movement of freight and people and also serves as a regional route for commuters to and from the Washington, DC metropolitan area and areas south up to Stafford and Fredericksburg. In December of 2011, the proposal to build Express Lanes by utilizing the existing HOV lanes in the median from Turkeycock to Route 234 (Dumfries Road) and constructing two new reversible lanes up to Route 610 (Garrisonville Road) was approved and the Express Lanes became operational in January However, this was part of a phased construction with the ultimate design extending the Express Lanes in the south up to Massaponax. The northern section of the project, included capacity expansion of the existing two lane reversible HOV facilities in Fairfax County and portions in Prince William County to a three lane reversible section. In the southern section, it included extending two new reversible lanes along the 9 mile segment within the median between Route 610 (Garrisonville Road) and the existing terminus south of Route 234 (Dumfries Road). As a result of this capacity increase north of Garrisonville Road, there was significant improvement in traffic operations and reduction in congestion during peak hours. In the southbound direction in the PM peak hours, vehicles destined to Route 610 and areas south, which were previously stuck in congestion north of Route 234 were no longer stuck. The traffic that was previously filtered due to the congestion was no longer metered and all reached the southern terminus of the Express Lanes just north of Route 610 sooner than before. This has resulted in a new bottleneck at the weaving section along I 95 southbound between the on ramp from the Express Lanes and the off ramp to Route 610. In the northbound direction in the AM peak hours the Express Lanes traffic can now enter through the new left side slip ramp that is approximately 1.5 miles north of the Route 610 interchange. Almost 30 percent of the traffic entering the Express Lanes at this location is from the Route 610 interchange. This traffic has to merge on the right and then weave across the three lanes of traffic to access the left side slip ramp. The remaining 70 percent that enter the Express Lanes from south of Route 610 also have to get into the left most lane to access the slip ramp. The volumes at the Route 610 interchange were already causing some congestion before the Express Lanes opened. With the additional weaving of Express Lanes traffic, this congestion in the northbound direction of I 95 has become worse in the AM peak period. The Virginia Department of Transportation (VDOT), in partnership with Transurban, proposes to extend the I 95 Express Lanes and create a new terminus for the southbound direction and new left side entrance for the northbound direction that will be located just south of the Route 610 interchange. This will take the traffic from the Express Lanes that is destined to and from south of Route 610 out of the influence area of the Route 610 interchange. This report presents the results of the traffic operational analysis of the proposed extension. 1 P age

7 2 Purpose and Need Under the current design, in the southbound direction in the PM peak period, all vehicles in the Express Lanes have to exit at the flyover ramp just north of Route 610 and merge into the auxiliary lane to westbound Route 610. The vehicles destined to eastbound Route 610 and to south of Route 610 have to weave across to get into the through lanes. The existing counts show that there are approximately 1100 vehicles from the Express Lanes making this maneuver and weaving with more than 1770 vehicles from I 95 southbound general purpose exiting to Route 610. Before the Express Lanes were functional, there was a huge bottleneck at the southbound terminus of the HOV lanes at Dumfries as seen in Figure 1 below. The figure also shows that with the opening of the Express Lanes, the congestion in the north was almost dissipated and a new bottleneck was created at the southern terminus of the Express Lanes off ramp north of Route 610. It also meant that more traffic that was destined to areas farther south, were able to reach there sooner than when they were metered by congestion before. This also exasperated conditions south of Route 610 where the demand increased the existing three lane capacity. Figure 1 shows a speed congestion diagram for the I 95 southbound direction on an average weekday before and after the Express Lanes during the PM peak period. Figure 1: Speed Congestion Diagram showing conditions Before and After the I 95 Express Lanes in the southbound direction of travel (Source INRIX) 2 P age

8 In the northbound direction in the AM peak period, vehicles from Route 610 have approximately 1.5 miles to merge into the I 95 northbound lanes and weave across three lanes to get into the leftside slip ramp entrance to the Express Lanes. The existing counts show that there are more than 270 vehicles making this maneuver along with another 640 vehicles from south of Route 610 which also try to weave into the left most lane to enter the Express Lanes at this slip ramp. Figure 2 below shows a speed congestion diagram for the I 95 northbound direction on an average weekday before and after the Express Lanes during the AM peak period. It can be seen that there was some congestion in the I 95 northbound direction before the Express Lanes mainly due to the demand from Route 610 entering the I 95 general purpose lanes. With the Express Lanes left side on ramp just north of the Route 610 interchange, this congestion has now increased and goes beyond the Route 630 interchange. Figure 2: Speed Congestion Diagram showing conditions Before and After the I 95 Express Lanes in the northbound direction of travel (Source INRIX) Future forecasts volumes show that there will be a significant increase in the southbound and northbound weaving volumes making operations and safety much worse. The purpose of this project is to relieve the recurring peak period congestion and reduce crash potential along I 95 in the northbound and southbound direction that is caused by the Express Lanes volumes entering/exiting at this southern entrance/terminus. Analyses performed as a part of this study support the following needs for improvements: 3 P age

9 Alleviate daily recurring congestion along northbound I 95 general purpose lanes by providing a new entrance south of the Route 610 interchange that will remove the vehicles entering the Express Lanes from south of Route 610 from the influence area of the Route 610 interchange. Alleviate daily recurring congestion along southbound I 95 general purpose lanes and queues along the Express Lanes southern terminus off ramp, by extending one lane of the Express Lanes past the existing flyover exit ramp and providing a separate off ramp for vehicles going south of Route 610, thus removing these vehicles from the influence area of the Route 610 interchange. Reduce potential for crashes along the weaving segment of I 95 southbound at the southern terminus. Due to the heavy weaving volumes in this segment and with the increase in future demand, the operation and safety concerns on southbound I 95 will be exacerbated. This project is needed to reduce the number of weaving vehicles and thus enhance safety on southbound I 95. Improve safety along northbound I 95 through the Route 610 interchange by reducing the number of vehicles that will enter the Express Lanes before the interchange as a result of this project and thus improve safety on northbound I Study Area 3.1 Project Location Map Figure 3 shows the existing terminus and entrance to the Express Lanes in the southern section of I 95. It shows the Study Area for the traffic operations analysis which included one interchange on each side of the Route 610 interchange. The operations analysis follows FHWA guidelines (Interstate System Access Informational Guide) that indicate the need to include an area of influence beyond the proposed improvements based on traffic operations and safety concerns. Therefore, the study area for operational and safety analysis is centered on the approximately 2.5 mile stretch of project location and extends to the next adjacent interchange on either side, as well as adjacent intersections on the crossing arterials as shown in Figure Study Area Boundaries and Facilities Included The study encompasses the section of southern terminus of the I 95 Express lane. This includes the I 95 corridor (GP and Express Lanes) from the Russell Road interchange to the Courthouse Road interchange and the corresponding ramp termini intersections. Table 3 1 summarizes the interchanging crossroads included in the study area and the intersections along these crossroads that have been analyzed. 4 P age

10 Crossroad Interchange Russell Road Route 610 (Garrisonville Road) Route 630 (Courthouse Road) Table 3 1 Intersection Analyzed Cross Street Intersections to be Considered Russell Road and I 95 SB On/Off Ramp Russell Road and I 95 NB Off Ramp Russell Road and I 95 NB On Ramp Garrisonville Road and Salisbury Drive/Stafford Market Place Jefferson Davis Highway (US 1) and I 95 NB Off Ramp Jefferson Davis Highway (US 1) and I 95 NB On Ramp Garrisonville Road/Washington Drive and Jefferson Davis Highway (US 1) Courthouse Road and I 95 SB On/Off Ramp Courthouse Road and I 95 NB On/Off Ramp 5 P age

11 I-95 Express Lanes Southern Terminus Traffic Operations Report N Russell Rd Interchange I-95 EL flyover Off- Ramp (Southbound) I-95 EL left-side On- Ramp (Northbound) Garrisonville Rd Interchange Route 630 Interchange Figure 3: Study Area 6 P age

12 4 Screening of Alternatives In addition to the No Build Alternative, four additional alternatives for the southbound direction, and one more for the northbound direction were evaluated. The alternatives including the preferred Build Alternative were further refined after traffic analyses were conducted to test the impacts due to the location of the tie in of the ramps and the demand of the analyses years. After reviewing the traffic operations, overall environmental impacts, right of way impacts, utility impacts, and construction costs, VDOT identified the final Preferred Build Alternative for the northbound entrance and the southbound exit ramps from the Express Lanes because it provided the most favorable cost benefit of all other alternatives that were evaluated. Detailed traffic operations and safety analyses were carried out for the Study Area shown in Figure 3 that included one interchange on each side (Route 630 in the south and Russell Road in the north). 5 Proposed Action in the Preferred Build Alternative The Preferred Alternative proposes to extend the Express Lanes south of the current southbound terminus at the flyover off ramp north of Route 610 interchange. A single reversible lane will be extended in the median up to the Route 610 bridge. South of that the northbound and southbound lanes will split. The southbound lane will continue south and will merge on the left side of I 95 southbound general purpose lanes approximately 1500 feet south of the last merge from Route 610. The northbound lane will diverge from the I 95 northbound general purpose lanes on the leftside approximately 1000 feet south of the first exit to US 1/Garrisonville Rd and will merge into the single reversible lane at the split. Figure 4 shows the concept drawing for the Preferred Alternative improvements laid over the existing conditions in the background. 7 P age

13 Figure 4: Preferred Alternative Concept 8 P age

14 6 Existing Conditions 6.1 Existing Road Geometry & Access Locations The existing I 95 Express Lane operates within the median of I 95 and consists of a three lane reversible, limited access express route from the transition to the existing I 395 HOV lanes to just north of the Prince William Parkway interchange (Exit 158), where it reduces to two lanes until north of Route 610 (Garrisonville Road Exit 143). The facility is constructed with 11 to 12 footwide travel lanes and variable shoulder widths. The existing AM entrance ramp and PM exit ramp between the GP and HOT lanes to allow movement between the two facilities are located between Garrisonville Road and Russell Road. Existing interchanges that provide access to the I 95 GP lanes in the vicinity of the Study Area exist at the interchanges with Route 630, Route 610 and Russell Road. 6.2 Existing Operational & Safety Conditions Detailed information on existing traffic volumes, traffic operations, and safety characteristics are included in Chapters 8, 9, and 10 respectively. The data in these chapters is shown as a baseline for the purposes of understanding future traffic operations and safety considerations under future scenarios. 7 Alternatives Considered This chapter describes the development and screening of alternatives that were considered to alleviate the congestion at the southern terminus of the I 95 Express Lanes within the Study Area. 7.1 Alternative Development and Previous Work The VDOT Megaprojects team was tasked to develop a mitigation to address the recurring congestion described in this report at the southern terminus of the I 95 Express Lanes. Keeping in mind the purpose and need of the project, various alternatives were developed for the northbound and southbound directions in conjunction with Transurban (the concessionaire of the I 95 Express Lanes), VDOT Fredericksburg district and FHWA. Each alternative was evaluated for the cost to build vs. the traffic operations and safety benefit it would provide. The benefits of different alternatives were compared with each other and with the No Build conditions (where no improvements are made and existing conditions are maintained) for proposed opening year (2018), opening year for Diverging Diamond Interchange (DDI) at Route 630 (2020), intermediate year (2030) and for design year (2035).. Figure 5 and Figure 6 shows the development of various alternatives that were evaluated while developing the preferred alternative for the northbound and southbound directions, respectively. 9 P age

15 2018 (opening yr) No Build Alt 1/2 Stn 190 Stn 200 Stn (DDI opening yr) Aux Lane Stn 200 Existing 2030 (intermediate yr) No Build Stn 200 Aux Lane Stn 200 No Build Stn (design yr) Alt 1/2 Stn 200 Stn 212 Aux Lane Stn 200 Figure 5: Northbound (AM Peak) scenarios 2018 (opening yr) No Build Alt 1/2 Stn 185 Stn (DDI opening yr) Aux Lane Stn 193 Existing 2030 (intermediate yr) No Build Stn 193 Aux Lane Stn 193 No Build Stn (design yr) Alt 1/2 Stn 193 Aux Lane Stn 193 Figure 6: Southbound (PM Peak) scenarios 10 P age

16 7.2 Transportation Systems Management (TSM) Options Transportation System Management (TSM) focuses on improving the operational efficiency of transportation systems without major system improvements (such as adding lanes or new ramps). Freeway TSM strategies can include signing and pavement striping improvements, traffic surveillance and control equipment, incident management programs, HOV facilities, and ramp metering. Corridor and system wide TSM strategies may incorporate improvements to mass transit service, multi modal facilities, and intelligent transportation systems. Due to the nature of the purpose and need of the project, TSM options alone will not address the operational and safety issues associated with this project. However, the Preferred Alternative identified here accounts for TSM strategies already in place as part of the I 95 HOV/HOT Lanes Project, and is configured to accommodate these strategies, consistent with FHWA s Policy Point 2 for Interstate Access. 7.3 No Build Alternative The No Build Alternative provides a baseline of conditions against which to compare the Build Alternative. Under the No Build Alternative, the proposed extension of the Express Lanes would not be constructed and I 95 would remain in its present configuration, with the existing southbound terminus at the flyover north of Route 610 and the northbound entrance at the left side slip ramp 1.5 miles north of Route 610 interchange. Most other existing roads would also generally remain in their present configurations. However, the financially constrained long range transportation plans of FAMPO and the National Capital Region Transportation Planning Board contain a number of other projects funded for construction in the region. These were assumed to be in place for the analysis years including intermediate year (2020) and design year (2035) and were taken into account in the road network assumed for traffic forecasting efforts of the assumed future no build conditions for this project. One of the key projects that would influence this project is the construction of a Diverging Diamond Interchange (DDI) at the Route 630 interchange which is under way. The opening year for the DDI at Route 630 is 2020 and hence the analysis conducted form the alternative carried forward included looking at the 2020 as opening year and 2035 as design year. 7.4 Refinement of Preferred Build Alternative The refinement alternatives described in the previous section were discussed with the project stakeholders and it was determined that one alternative for the northbound direction and four alternatives for the southbound direction would undergo detailed analysis for traffic operations, overall environmental impacts, right of way impacts, utility impacts, and construction cost. These alternatives are shown in Figure 7 and Figure 8 for the northbound and southbound screened build alternatives respectively. 11 P age

17 Figure 7: Northbound (AM peak) Alternative 12 P age

18 Figure 8: Southbound (PM peak) Alternatives 13 P age

19 Table 2 lists the No Build and four alternative scenarios that were analyzed and the conditions assumed under each of the alternatives. Under all scenarios it is assumed that the Route 630 interchange will be redesigned to a Diverging Diamond Interchange (DDI). Under Scenario 1 it is proposed to add an auxiliary lane along I 95 southbound between the merge from the eastbound Route 610 on ramp and the diverge to Route 630. Scenario 2 is similar to Scenario 1 and it is proposed to extend the Express Lanes and provide a left side merge to the general purpose lanes approximately 1000 south of the on ramp from eastbound Route 610. Scenario 3 is similar to Scenario 2 but it does not include the auxiliary lane along I 95 southbound between Route 610 and Route 630. Scenario 4 is similar to Scenario 3, with the exception that the proposed Express Lanes left side merge to the general purpose lanes will be extended to south of the Route 630 interchange and will merge approximately 1000 south of the on ramp from Route 630. Table 2: Alternatives analyzed for I 95 Southbound PM Peak Scenarios DDI Aux Lane New EL Ramp No Build Yes No No Scenario 1 Yes Yes No Scenario 2 Yes Yes Yes 1 Scenario 3 Yes No Yes 1 Scenario 4 Yes No Yes 2 1 Express Lanes merge south of Garrisonville Rd 2 Modified Express Lanes merge south of Courthouse Rd The main criteria that were used by VDOT to evaluate the screened alternatives discussed above are: 1. Traffic operations 2. Construction cost 3. Right of way impacts 4. Overall environmental impacts 5. Utility impacts Based on these criteria, VDOT identified the final Preferred Build Alternative for the northbound entrance and the southbound exit ramps from the Express Lanes because it provided the most favorable cost benefit of all other alternatives that were evaluated. A concept drawing for the Preferred Alternative is shown in Figure 4 and findings of the detailed traffic operations and safety analyses that were carried out for the Study Area are listed in the following chapters. 14 P age

20 8 Traffic Volume Projections This section provides an overview of the assumptions and methodology used for forecasting traffic volumes for the traffic operational analysis conducted for this study. 8.1 Traffic Analysis Years Traffic operations were evaluated for current conditions (2015), the interim year (2020) when the DDI at Route 630 opens and the design year (2035) for the screened alternatives described in the previous chapter. The analyses include No Build and Build alternatives for both 2020 and 2035 scenarios. 8.2 Traffic Data Collection In order to conduct the operational analysis for this analysis, traffic data was collected during spring of 2015 and included: 24 hour traffic counts at all ramp locations within study area and along the mainline of I 95. Traffic count data along the Express Lanes and the off and on ramps from I 95 general purpose were provided by Transurban. Turning movement counts for 13 hours collected at every 15 minute interval at all intersections within study area. Peak period travel time runs were collected along the I 95 general purpose lanes. Signal timing data for all signalized intersections were requested from VDOT. Speed data was collected from INRIX. Origin Destination data for vehicles entering/exiting the Express Lanes from the Route 610 interchange were counted based on license plate video survey. Background growth data from recent studies such as I 95 IJR study and Route 630 IMR. Using this data, a balanced set of peak hour traffic volumes (7:00 AM 8:00 AM and 4:15 PM 5:15 PM) were developed for analyzing existing conditions. Figure 9 to Figure 11 show the daily traffic demand (ADT), AM peak hour, and PM peak hour traffic demands on all roadways and intersections within the Study Area respectively. 15 P age

21 Figure 9: Existing Average Daily Traffic 16 P age

22 Figure 10: Existing AM Peak Hour Volumes 17 P age

23 Figure 11: Existing PM Peak Hour Volumes 18 P age

24 8.1 Forecasting Methodology & Assumptions The future peak hour traffic demands were forecasted based on existing volumes and the annual growth rates: Table 3 shows the annual growth rate used for projecting future traffic volumes in 2020 and Growth factors were calculated from the forecasted volumes in the Interchange Justification Report of I 95 HOV/HOT lanes Project. o The 2011 existing volumes and 2018 forecasted volumes in the IJR were used to calculate annual growth rates from 2015 to 2020; o The 2011 existing volumes and 2035 forecasted volumes in the IJR were used to calculate annual growth rates from 2015 to 2035; Base year traffic volumes were grown using the calculated growth factors on freeways and arterials. The estimated future year volumes were reviewed and checked for capacity constraints. The demands were adjusted wherever demand exceeds available capacity. Forecast future link approach and departure volumes were obtained using the calculated growth factors. Forecast volumes along the corridor were re balanced, as appropriate. The daily traffic demands were generated from the peak hour volumes with the k factor of 9%. Table 3: Annual Traffic Growth Rates Freeways Annual Growth Rates Location AM PM AM PM I 95 NB Total South of I 95/Route % 2.8% 1.7% 1.6% I 95 NB Total South of I 95/US 1 3.6% 2.9% 1.9% 1.4% I 95 NB Total North of I 95/US 1 2.6% 2.6% 1.7% 1.6% I 95 NB Total North of I 95/USMC Truck Hwy 3.4% 1.4% 1.3% 1.2% I 95 SB Total North of I 95/Russell Rd 0.1% 1.9% 0.4% 1.0% I 95 SB Total North of I 95/Route % 1.7% 1.9% 1.3% I 95 SB Total South of I 95/Route % 2.2% 1.9% 1.7% I 95 SB Total South of I 95/Route % 2.5% 1.9% 1.6% Arterial Roadways Russell Rd EB 0.2% 0.8% 1.3% 1.5% Russell Rd WB 0.6% 0.4% 4.8% 4.6% Route 610 EB 3.8% 2.2% 2.2% 1.2% Route 610 WB 2.9% 3.5% 3.0% 1.9% US 1 NB 1.7% 7.0% 1.7% 3.8% US 1 SB 4.9% 2.7% 4.2% 1.9% Route 630 EB 8.3% 7.0% 4.1% 3.4% Route 630 WB West of I % 6.8% 3.5% 4.2% 19 P age

25 The daily and peak hour traffic demands used in the operational analysis for No Build and Build alternatives for intermediate year (2020) are shown in Figure 12 to Figure 17 and for the design year (2035) are shown in Figure 18 to Figure P age

26 Figure 12: Average Daily Traffic in 2020 for No Build Alternative 21 P age

27 Figure 13: AM Peak Hour Volumes in 2020 for No Build Alternative 22 P age

28 Figure 14: PM Peak Hour Volumes in 2020 for No Build Alternative 23 P age

29 Figure 15: Average Daily Traffic in 2020 for Build Alternative 24 P age

30 Figure 16: AM Peak Hour Volumes in 2020 for Build Alternative 25 P age

31 Figure 17: PM Peak Hour Volumes in 2020 for Build Alternative 26 P age

32 Salisbury Dr / Stafford Market Pl 90,700 88,800 90,300 90,300 78,300 85,600 75,900 83, ,800 90,100 95, ,100 84,900 94,900 11,000 6,200 98,200 85,800 I 95 Russell Rd Rt 630 / Courthouse Rd US 1 / Jefferson Davis Hwy Rt. 610 / Garrisonville Rd I-95 Express South Terminus 2035 No Build Average Daily Traffic Figure 18: Average Daily Traffic in 2035 for No Build Alternative 27 P age

33 Figure 19: AM Peak Hour Volumes in 2035 for No Build Alternative 28 P age

34 Figure 20: PM Peak Hour Volumes in 2035 for No Build Alternative 29 P age

35 Figure 21: Average Daily Traffic in 2035 for Build Alternative 30 P age

36 Figure 22: AM Peak Hour Volumes in 2035 for Build Alternative 31 P age

37 Figure 23: PM Peak Hour Volumes in 2035 for Build Alternative 32 P age

38 9 Traffic Operations Analyses All traffic analyses were performed for the AM and PM peak hours for the No Build and Build alternatives for intermediate year (2020) and design year (2035). The construction of the project is expected to start in 2017 and be completed by 2018, however the DDI at Route 630 will be completed by There is a significant influence of the Route 630 interchange redesign on this project. As a result, 2020 was used as the intermediate year instead of the opening year Methodology This section outlines the methodology used to provide measures of effectiveness (MOEs) in evaluating traffic operations for all scenarios. The methods and assumptions for this study were kept consistent with what was adopted for the I 95 HOV/HOT Lanes IJR developed in The primary tool used for the microsimulation analysis was the VISSIM microsimulation software package. In recognizing the limitations of deterministic analytical models such as Highway Capacity Software (HCS) and Synchro, it was determined that microsimulation would be more appropriate to evaluate traffic operations and performance of the interchange improvement alternatives in this study. VISSIM software was selected as the primary tool to provide the microscopic level of traffic operation analysis with an integrated consideration of the upstream and downstream impacts. In addition, Synchro (Version 8) software was used to develop optimized traffic signal timing for all future scenarios. However, Synchro was not used to report the intersection operations. The VISSIM models that were developed for the I 95 HOV/HOT Lanes IJR were used as the base models and were expanded to include the Route 630 interchange to the south. The models were truncated north of the Russell Road interchange to keep the analyses focused to the Study Area. Since the base IJR models were previously calibrated following guidance from FHWA s Traffic Analysis Toolbox Volume III: Guidelines for Applying Traffic Microsimulation Modeling software, to ensure that the model accurately replicated the conditions in the field additional model calibration was carried out to validate against new traffic data collected. The number of model runs (10) and the random seed numbers were kept consistent with what were used for the IJR. 9.2 Microsimulation Analyses Existing Conditions Calibration Northbound Travel Time Analysis Table 4 and Figure 24 compare free flow travel times, field travel times, and model travel times for Existing conditions in the AM peak hour. Travel time measurements were aggregated by direction of travel, and type of facility (GP and HOV lanes). The travel time summary is based on the following segment delineations. From Route 630 gore to Off Ramp to US 1 From Off ramp to US 1 to On ramp from US 1 From On ramp from US 1to Russell Road exit 33 P age

39 The travel time segments are measured at each interchange, typically either below an overpass or above an underpass of a bridge. The corridor travel times were compared against field observed travel times as a function of distance traveled. Four lines are plotted on the travel time figures. The red solid line represents the average of three field measured travel times. The blue line represents the travel time from the VISSM models. The objective of this graphic is to have the blue line match the red line as closely as possible while a secondary objective is to have the blue line within the minimum and maximum field observed travel times. Table 4: I 95 northbound general purpose lanes Travel Times (AM peak hour) AM Peak Hour for I 95 Northbound Travel Time (minutes) Free Flow Field VISSIM Model From Route 630 gore to Off Ramp to US 1 From Off ramp to US 1 to On ramp from US 1 From On ramp from US 1to Russell Road exit Total NB Mainline in AM Peak Hour In the morning peak hour in the northbound direction, the travel time for the corridor from Route 630 to Russell Road in the model was 10.2 minutes and the field travel time was 10.3 minutes. The overall difference in travel time for the entire corridor is 1 percent, which is within the calibration criteria. Figure 24: I 95 northbound general purpose lanes cumulative Travel Times (AM peak hour) 34 P age

40 Southbound Travel Time Analysis In the afternoon peak hour in the southbound direction, the travel time for the corridor from Russell Road to Route 630 in the model is 27.0 minutes and the field travel time is 19.3 minutes. The overall difference in travel time for the entire corridor is 28 percent as shown in Table 5. Figure 25 shows a cumulative comparison of field travel time and model travel times. There is a very good match in the travel time segment results between Route 610 and Route 630; within 10 percent. The segment between Russell Road and Route 610, the VISSIM model over predicts the travel times. However, as seen in the following segments, there is a very good match of speeds and throughputs in this segment compared to the field data. It is possible that on the day that the travel time data were collected, this segment may not be performing under average operating conditions. Table 5: I 95 southbound general purpose lanes Travel Times (PM peak hour) PM Peak Hour for I 95 Southbound Travel Time (minutes) Free Flow Field VISSIM Model From Russell Road Bridge to WB Exit to Route 610 From WB Off ramp to EB Onramp of Route 610 From EB On ramp from Route 610 to Route 630 exit Total SB Mainline in PM Peak Hour Figure 25: I 95 southbound general purpose travel times (PM peak hour) 35 P age

41 Northbound Speed Analysis for AM peak Figure 26 illustrates the model speed profiles in comparison to INRIX data for existing AM peak hour conditions. As seen in the congestion diagram the major bottleneck location in the AM peak direction is from the Route 630 to Route 610 in both VISSIM model and INRIX data. At the weave section between the northbound on ramp from US 1 and the slip ramp to the Express Lanes, the queue spills back south of the Route 610 interchange. This is also consistent with the field observation. A visual comparison of the two speed congestion diagrams indicate similarities in the location of bottleneck and the buildup and dissipation of the queues. Figure 26: I 95 northbound general purpose Speed Congestion diagram (AM peak hour) Southbound Speed Analysis for PM peak Figure 27 illustrates the model speed profiles in comparison to INRIX data for existing PM peak hour conditions. Both VISSIM model and INRIX data show that the congestion areas are along most of the corridor within the study area. This largely matches with the travel time analysis results. 36 P age

42 The major bottleneck happens at the north of Route 610 interchange, where the southern terminus of the Express Lanes is located and the flyover ramp merges in the GP lanes. With the high traffic demand exiting from southbound Express Lanes, the result is frequent merging, diverging and weaving that lead to slow moving vehicles and queuing during the PM peak. The average traveling speed is around mph in this section. Traffic operations are regularly stop and go in the PM peak. Along southbound Express Lanes, traffic flow operates at free flow conditions until it reaches the flyover ramp where the queues back up from the weave segment. Based on the VISSIM model and INRIX data, the I 95 southbound mainlines operate at free flow conditions at south of Route 630 interchange. However, it was observed that this was not the case during a field review. Queues were observed to spill back from the downstream interchange. I 95 GP Congestion Speed Profile Southbound PM Peak Hour (4:00 PM to 5:00 PM) Existing VISSIM Model INRIX 16:00 16:15 16:30 16:45 17:00 16:00 16:15 16:30 16:45 17:00 Russell Rd/Exit 148 Garrisonville Rd/Exit 143 Courthouse Rd/Exit 140 Figure 27: I 95 southbound general purpose Speed Congestion diagram (PM peak hour) Volume Served Analysis I 95 Northbound (AM peak hour) Table 6 shows the volume throughput from the model compared to the field demand for the mainline and ramps on the I 95 northbound direction in the AM peak hour. The table also summarizes the detailed GEH statistics. 37 P age

43 During the AM peak hour almost all subareas meet the GEH criteria, with the only exception of one mainline segment between I 95 NB Off ramp to Route 610 WB and I 95 NB On ramp from US 1. In other word, 95% of all segments meet the required GEH value less than 5. Table 6: I 95 Northbound Freeway Mainline and Ramp Demand vs. Throughput (AM peak hour) Segment Description Demand (veh/hr) Throughput (veh/hr) GEH I 95 MAINLINE (General Purpose) South of I 95 NB Off ramp to Route Between I 95 NB Off ramp to Route 630 and I 95 NB On ramp from Route 630 Between I 95 NB On ramp from Route 630 and I 95 NB Off ramp to US 1 Between I 95 NB Off ramp to US 1 and I 95 NB Onramp from Route 610 EB Between I 95 NB On ramp from Route 610 EB and I 95 NB Off ramp to Route 610 WB Between I 95 NB Off ramp to Route 610 WB and I 95 NB On ramp from US 1 Between I 95 NB On ramp from US 1 and I 95 NB HOT lane entrance Between I 95 NB HOT lane entrance and I 95 NB Offramp to Russell Rd Between I 95 NB Off ramp to Russell Rd and I 95 NB On ramp from Russell Rd North of I 95 NB On ramp from Russell Rd RAMPS To/From I 95 MAINLINE I 95 NB Off ramp to Route I 95 NB On ramp from Route I 95 NB Off ramp to US I 95 NB On ramp from Route 610 EB I 95 NB Off ramp to Route 610 WB I 95 NB On ramp from US I 95 NB Slip Ramp to HOT lane I 95 NB Off ramp to Russell Rd I 95 NB On ramp from Russell Rd P age

44 Volume Served Analysis I 95 Southbound (PM peak hour) Table 7 shows the volume throughput from the model compared to the field demand for the mainline and ramps on the I 95 southbound direction in the PM peak hour. The table also summarizes the detailed GEH statistics. During the PM peak hour, 85 percent of all locations meet the required GEH value. Specifically, all ramp locations are within the required GEH value. Table 7: I 95 Southbound Mainline and Ramp Demand vs. Throughput (PM peak hour) Segment Description Demand (veh/hr) Throughput (veh/hr) GEH I 95 MAINLINE (General Purpose) North of I 95 SB Off ramp to Russell Rd Between I 95 SB Off ramp to Russell Rd and I 95 SB Onramp from Russell Rd Between I 95 SB On ramp from Russell Rd and I 95 SB Slip ramp from HOT lane Between I 95 SB Slip ramp from HOT lane and I 95 SB Off ramp to Route 610 WB Between I 95 SB Off ramp to Route 610 WB and I 95 SB On ramp from Route 610 WB Between I 95 SB On ramp from Route 610 WB and I 95 SB Off ramp to Route 610 EB Between I 95 SB Off ramp to Route 610 EB and I 95 SB On ramp from Route 610 EB Between I 95 SB On ramp from Route 610 EB and I 95 SB Off ramp to Route 630 Between I 95 SB Off ramp to Route 630 and I 95 SB Onramp from Route South of I 95 SB On ramp from Route RAMPS To/From I 95 MAINLINE I 95 SB Off ramp to Russell Rd I 95 SB On ramp from Russell Rd I 95 SB Slip Ramp from HOT lane I 95 SB Off ramp to Route 610 WB I 95 SB On ramp from Route 610 WB I 95 SB Off ramp to Route 610 EB I 95 SB On ramp from Route 610 EB I 95 SB Off ramp to Route I 95 SB On ramp from Route P age

45 9.2.2 Existing Conditions Analysis Findings Freeway Density Analysis (AM peak hour) As summarized in Table 8, in the AM peak hour under the existing scenario there are eight basic segments and two weave segments in the GP lanes of I 95 in the northbound direction. Of these basic segments, two operate under severe congestion, one operates under heavy congestion and the remaining five segments operate at an acceptable level. Out of the two weave segments, one operates under severe congestion and the other under heavy congestion. There is one basic segments in the Express Lanes and it currently operates at an acceptable level of LOS A. Table 8: I 95 Northbound Freeway Density and Speeds (AM peak hour) Mainline Segment Description Average Density (veh/mi/ln) Average Speed (mph) LOS South of I 95 NB Off ramp to Route C Between I 95 NB Off ramp to Route 630 and I 95 NB Onramp from Route 630 Between I 95 NB On ramp from Route 630 and I 95 NB Offramp to US 1 Between I 95 NB Off ramp to US 1 and I 95 NB On ramp from Route 610 EB Between I 95 NB On ramp from Route 610 EB and I 95 NB Off ramp to Route 610 WB* Between I 95 NB Off ramp to Route 610 WB and I 95 NB On ramp from US 1 Between I 95 NB On ramp from US 1 and I 95 NB HOT lane entrance* Between I 95 NB HOT lane entrance and I 95 NB Off ramp to Russell Rd Between I 95 NB Off ramp to Russell Rd and I 95 NB Onramp from Russell Rd C E F F F E C C North of I 95 NB On ramp from Russell Rd C I 95 NB Express Lanes 5 71 A *: Weave segment The ramp junction analysis is summarized in Table 9. There are a total of nine ramp junctions out of which only one segment operates under severe congestion and the remaining eight segments operate at an acceptable level. 40 P age

46 Table 9: I 95 Northbound Ramp Density and Speeds (AM peak hour) Ramp Description Average Density (veh/mi/ln) Average Speed (mph) LOS I 95 NB Off ramp to Route B I 95 NB On ramp from Route B I 95 NB Off ramp to US D I 95 NB On ramp from Route 610 EB F I 95 NB Off ramp to Route 610 WB B I 95 NB On ramp from US C I 95 NB Slip Ramp to HOT lane 5 71 A I 95 NB Off ramp to Russell Rd B I 95 NB On ramp from Russell Rd 2 44 A Freeway Density Analysis (PM peak hour) During the PM peak hour, the basic segment in the Express Lanes operates under acceptable LOS, while none of mainline segments in the general purpose lanes of I 95 southbound operate at an acceptable level as shown in Table 10. The queue on the off ramp from the Express Lanes at the southern terminus does every once in a while spill back onto the Express Lanes mainline. However, it does not happen as frequently to degrade operating conditions along the basic segment over the peak hour. Only one basic segment operates under heavy congestion and the remaining seven basic segments and two weave segments operate under severe congestion. Table 10: I 95 Southbound Freeway Density and Speeds (PM peak hour) Mainline Segment Description Average Density (veh/mi/ln) Average Speed (mph) LOS North of I 95 SB Off ramp to Russell Rd F Between I 95 SB Off ramp to Russell Rd and I 95 SB Onramp from Russell Rd Between I 95 SB On ramp from Russell Rd and I 95 SB Slip ramp from HOT lane Between I 95 SB Slip ramp from HOT lane and I 95 SB Off ramp to Route 610 WB* Between I 95 SB Off ramp to Route 610 WB and I 95 SB On ramp from Route 610 WB Between I 95 SB On ramp from Route 610 WB and I 95 SB Off ramp to Route 610 EB* F F F F F 41 P age

47 Between I 95 SB Off ramp to Route 610 EB and I 95 SB On ramp from Route 610 EB Between I 95 SB On ramp from Route 610 EB and I 95 SB Off ramp to Route 630 Between I 95 SB Off ramp to Route 630 and I 95 SB Onramp from Route F F F South of I 95 SB On ramp from Route E I 95 SB HOT Lanes A *: Weave segment The ramp junction analysis is summarized in Table 11. Out of the nine ramp segments, two operate under severe congestion, one with heavy congestion, and the remaining six operate at an acceptable level. Table 11: I 95 Southbound Ramp Density and Speeds (PM peak hour) Ramp Description Average Density (veh/mi/ln) Average Speed (mph) LOS I 95 SB Off ramp to Russell Rd 5 53 A I 95 SB On ramp from Russell Rd F I 95 SB Slip Ramp from HOT lane F I 95 SB Off ramp to Route 610 WB E I 95 SB On ramp from Route 610 WB 9 34 A I 95 SB Off ramp to Route 610 EB B I 95 SB On ramp from Route 610 EB C I 95 SB Off ramp to Route A I 95 SB On ramp from Route B Intersection Analysis (AM and PM peak hour) Figure 28 summarizes the intersection LOS for Existing conditions (AM and PM peak hour). A total of 10 intersections were analyzed in the study area. The study intersections are either ramp terminal intersection of adjacent to them on either side of the interchange. In the AM peak hour, one of the intersections operates at LOS F while two others operating at LOS E. The remaining intersections operate at LOS D or better. Overall, most of intersections are operating fairly well. All three intersections operating worse than LOS D are located at the Route 610 interchange. 42 P age

48 In the PM peak hour, only half intersections (five) are operating at LOS D or better. Russell Road interchange and Route 630 interchange have one intersection each operating at LOS E. All three intersections operating worse than LOS D are located at the Route 610 interchange. Figure 28: Intersection LOS for Existing conditions (AM and PM peak hour) Existing Conditions Summary of Findings AM Peak In the AM peak, the northbound direction is the peak travel direction as commuters travel to Washington DC. Some of the key points are summarized below: Along northbound I 95 in the GP lanes, the total travel time to traverse the entire corridor is 10.3 minutes which is approximately 50 percent more than the free flow travel time. The major bottleneck is the weave section between the on ramp from US 1 to the slip ramp to the HOT lanes. The bottleneck causes the congestion downstream of mainlines to the Courthouse interchange. Approximately 20 percent of the study segments on I 95 are operating at severely congested levels. HOT lanes are under utilized and operate at free flow conditions. PM Peak In the PM peak, the peak direction on I 95 is southbound as a vital route for commuters leaving Washington DC for key destinations in the surrounding suburban areas. Our simulation analysis well duplicated the overall field condition in terms of travel time, speed profiles and throughput volumes. The results indicate severe traffic congestions along the southbound corridor. Some of the key points are summarized below: Along southbound I 95 in the GP lanes, the total travel time to traverse the entire corridor is 19.3 minutes which is almost three times of the free flow speed. 43 P age

49 Average speeds along the corridor in the GP lanes range between 10 and 30 mph. HOT lanes operate at an acceptable level except the location close to the slip ramp exit Approximately 55 percent of the segments are operating at severely congested levels I-95 Northbound AM Peak Hour Alternatives Analyses Using the existing conditions VISSIM models as base, the future conditions VISSIM models were developed. For the northbound direction there was only one scenario that was carried forward for detailed analyses which is referred to as the Build conditions scenario. Figure 4 shows the concept of the Build conditions and the results of this scenario are provided below. The same number of runs and the same random seed numbers were used while making the VISSIM runs for all the future No Build and Build alternatives Travel Time results (No Build vs. Build Alternatives) In the AM peak hour the travel times in the I 95 northbound general purpose lanes will become worse under No Build conditions in 2020 compared to existing conditions as seen in Figure 29. However, with the proposed Build alternative, the total travel time from Route 630 to Russell Road will be reduced by approximately 6 minutes. Most of the travel time savings will be south of the Route 610 interchange. Existing 17.1 mins 2020 No Build 17.6 mins 2020 Build 11.5 mins Figure 29: Cumulative Travel Time comparisons between 2020 No Build and Build 44 P age

50 Travel Time results (No Build vs. Build Alternatives) As seen in Figure 30 by 2035 if no improvements are made the travel times in the I 95 northbound general purpose lanes will become worse compared to the 2020 No Build conditions. However, with the proposed Build alternative, the total travel time from Route 630 to Russell Road will be reduced by approximately 4 minutes. Most of the travel time savings will be south of the Route 610 interchange. The savings in travel times are less in 2035 compared to 2020 because of the downstream capacity constraints south of the Route 630 interchange No Build 17.6 mins 2035 No Build 18.2 mins 2035 Build 14.0 mins Figure 30: Cumulative Travel Time comparisons between 2035 No Build and Build Speed Congestion results (No Build vs. Build Alternatives) Figure 31 shows a comparison of the speed congestion diagrams for all the No Build and Build alternatives for existing and future conditions. The horizontal axis represents the time lapse and the vertical axis is the distance with the direction of travel being from the bottom to the top of the figure. As seen from the figure, if no improvements are made under the No Build conditions, the congestion that is there under existing conditions will further degrade and queues will spill back even farther beyond the Route 630 interchange. With the proposed improvement, this congestion is almost gone in 2020 and then by 2035, due to the increase in demand from Route 610, there is some congestion at this interchange but it is not as bad as under existing conditions. 45 P age

51 Figure 31: Speed Congestion comparisons between 2020 and 2035 No Build and Build Alternatives (AM peak hour) I-95 Southbound PM Peak Hour Alternatives Analyses As described in Section 7.4, four different Build conditions scenarios were evaluated in the southbound direction along with the No Build conditions for 2020 and Figure 8 shows graphically the difference in the four Build alternatives and Table 2 lists the differences in the assumptions for each scenario. Using the existing conditions VISSIM models as base, each Build conditions scenario model was developed and analyzed. The results of each scenario along with a comparison with the No Build conditions are provided below Travel Times, Throughputs and Average Queues all Scenarios Table 12 below lists the travel times, throughputs and queues along the general purpose (GP) and Express Lanes (EL) in 2020 for all the scenarios. Table 13 provides the same information for all the scenarios as compared to the No Build conditions. 46 P age

52 Table 12: I 95 southbound scenarios Travel Times, Throughputs & Average Queues (2020) 2020 Analysis Year No Build Scenario 1 Scenario 2 Scenario 3 Scenario 4 GP Travel Time from Russell Rd to Route 610 (minutes) GP Travel Time from Russell Rd to south of Route 630 (minutes) EL Travel Times from Russell Rd to Route 610 (minutes) EL Travel Times from Russell Rd to south of Route 630 (minutes) Throughputs GP from Russell Rd to Route 610 (Veh/hr) Throughputs GP from Route 610 south of Route 630 (Veh/hr) Queues on existing EL Flyover ramp (feet) ,700 5,004 5,431 4,562 4,849 5,943 5,944 5,902 5,945 6,054 3,209 1,189 Table 13: I 95 southbound Travel Times, Throughputs & Average Queue All Scenarios compared to No Build (2020) 2020 Analysis Year No Build (Total) Scenario 1 (Delta*) Scenario 2 (Delta*) Scenario 3 (Delta*) Scenario 4 (Delta*) GP Travel Time from Russell Rd to Route 610 (minutes) GP Travel Time from Russell Rd to south of Route 630 (minutes) EL Travel Times from Russell Rd to Route 610 (minutes) EL Travel Times from Russell Rd to south of Route 630 (minutes) Throughputs GP from Russell Rd to Route 610 (Veh/hr) 4, Throughputs GP from Route 610 south of Route 630 (Veh/hr) 5, Queues on existing EL Flyover ramp (feet) 3,209 2,021 3,209 3,209 3,209 * Positive number indicates increase and Negative number indicates decrease The results show that in 2020, all build alternatives will mostly improve conditions compared to the No Build conditions for general purpose (GP) and Express Lanes (EL) traffic. Scenario 2 provides the most benefit overall with improvements in travel times for GP and EL traffic and an increase in throughput and elimination of the queues on the existing EL flyover ramp. However, this is also the most costly alternative to build. Scenario 1 provides benefit to the GP traffic but does not benefit the EL traffic much and there still are queues on the existing EL flyover ramp. Scenario 3 and Scenario 4 seem to provide similar overall benefits with Scneario 3 being the less costly option to build. 47 P age

53 Travel Times, Throughputs and Average Queues all Scenarios Similar to 2020, Table 14 below lists the travel times, throughputs and queues along the general purpose (GP) and Express Lanes (EL) in 2035 for all the scenarios. Also, Table 15 provides the comparison of all the scenarios as with the No Build conditions. Table 14: I 95 southbound scenarios Travel Times, Throughputs & Average Queues (2035) 2035 Analysis Year No Build Scenario 1 Scenario 2 Scenario 3 Scenario 4 GP Travel Time from Russell Rd to Route 610 (minutes) GP Travel Time from Russell Rd to south of Route 630 (minutes) EL Travel Times from Russell Rd to Route 610 (minutes) EL Travel Times from Russell Rd to south of Route 630 (minutes) Throughputs GP from Russell Rd to Route 610 (Veh/hr) Throughputs GP from Route 610 south of Route 630 (Veh/hr) Queues on existing EL Flyover ramp (feet) ,303 4,825 4,867 4,486 4,543 5,939 5,967 5,965 5,962 6,092 5,264 4,267 Table 15: I 95 southbound Travel Times, Throughputs & Average Queue All Scenarios compared to No Build (2035) 2035 Analysis Year No Build (Total) Scenario 1 (Delta*) Scenario 2 (Delta*) Scenario 3 (Delta*) Scenario 4 (Delta*) GP Travel Time from Russell Rd to Route 610 (minutes) GP Travel Time from Russell Rd to south of Route 630 (minutes) EL Travel Times from Russell Rd to Route 610 (minutes) EL Travel Times from Russell Rd to south of Route 630 (minutes) Throughputs GP from Russell Rd to Route 610 (Veh/hr) 4, Throughputs GP from Route 610 south of Route 630 (Veh/hr) 5, Queues on existing EL Flyover ramp (feet) 5, ,264 5,264 5,264 * Positive number indicates increase and Negative number indicates decrease The results show that in 2035, all build alternatives will mostly improve conditions compared to the No Build conditions for general purpose (GP) and Express Lanes (EL) traffic. Similar to what we saw in 2020, Scenario 2 provides the most benefit overall with improvements in travel times for GP and EL traffic and an increase in throughput and elimination of the queues on the existing EL flyover ramp. Scenario 1 provides benefit to the GP traffic but does not benefit the EL traffic much and the queues on the existing EL flyover ramp are longer compared to 2020 conditions. Scenario 3 48 P age

54 and Scenario 4 seem to provide similar overall benefits with Scneario 3 being the less costly option to build. Also, the VISSIM model does not include the I 95 segments north of Russell Road. By 2035 the congestion and queues along I 95 southbound general purpose lanes will spill back farther north of Russell Road. So with any improvements along I 95 southbound between Russell Road and Route 610 will alleviate congestion north of Russell Road as well. This additional benefit is not captured here in this analysis. So the benefits from the Build conditions will likely be greater than what is reported in this study I-95 Southbound PM Peak Hour Summary and Preferred Alternative After reviewing the traffic operations, overall environmental impacts, right of way impacts, utility impacts, and construction costs, VDOT identified Scenario 3 as the final Preferred Build Alternative for the southbound terminus of the Express Lanes because it provided the most favorable costbenefit of all other alternatives that were evaluated. Going forward Scenario 3 is referred to as the Build Alternative for the PM peak hour conditions. Figure 4 shows the concept of the Build conditions. As seen in Figure 32, there is a capacity constraint just south of the Route 630 interchange and with the relief in congestion in the north, there will be more throughput reaching this bottleneck earlier degrading operations further. In both the 2020 and 2035 No Build conditions the congestion along I 95 GP gets worse north of the existing EL flyover ramp. The queues go beyond the VISSIM network and do not dissipate during the peak period that was analyzed. With the Build alternative, conditions improve north of Route 610 but south of Route 610, things get a little worse and offset the benefits captured between Russell Rd and Route 610. If the downstream capacity constraints south of Route 630 were to be addressed, the benefits from this scenario would be much greater. Figure 32: Speed Congestion comparisons between 2020 and 2035 No Build and Build Alternatives (PM peak hour) 49 P age

55 10 Safety Analyses This chapter presents the safety analysis that was conducted for this study based on reported crash data available from the last three years ( ) from milepost 139 south of Route 630 up to milepost north of Russell Road. The analysis was performed in accordance with the methods identified in FHWA s Interstate System Access Informational Guide Data Collection & Analysis Methodology Crash data for the I 95 southbound and northbound mainline and ramps within the study area were obtained from VDOT for the most recent three year period available ( ). It should be noted that the database only includes crashes that were reported to police. It also does not include data after the Express Lanes were operational. Furthermore during this three year period, there was construction activity going on for the Express Lanes near the Route 610 interchange and the crash data may not be representative of typical conditions. Hence, the study team requested additional raw data for 2015 and received data for January through April data for 2015 for the Route 610 interchange Historical Crash Frequency Figure 33 below shows the summary of the crash rate calculated based on the total crashes reported in the three year period within the Study Area. It can be seen that in the northbound direction the crashes increase as you go north especially through the Route 610 interchange. In the southbound direction there are more crashes north of Route 610 interchange which can potentially get worse now with the existing Express Lanes southern terminus in this segment. Also, south of Route 630 the crashes are higher possibly due to the bottleneck conditions caused by the capacity constraints. This location has also seen an increase in congestion after the opening of the Express Lanes as a result of which could the safety in this section of I 95 could be negatively impacted. 50 P age

56 Figure 33: I 95 mainline summary of crash rate within Study Area In terms of the severity of the crashes Table 16 and Table 17 shows the total crashes within the Study Area and their severity. Out of a total of 827 total crashes in the northbound direction, there were 3 fatalities and almost 24% of the crashes involved some injury. In the southbound direction, out of a total of 729 crashes, almost 25% involved some injury while there were no reported fatality during the three year period. Table 16: I 95 northbound mainline summary of total crashes by severity Fatality Injury PDO Total Crashes South of Route 630 (139 to ) Route 630 to Route 610 ( to ) Route 610 to Russell Rd ( to 149.6) Table 17: I 95 southbound mainline summary of total crashes by severity Fatality Injury PDO Total Crashes South of Route 630 (139 to ) Route 630 to Route 610 ( to ) Route 610 to Russell Rd ( to 149.6) Figure 34 and Figure 35 show a summary of total crashes by type for I 95 northbound and southbound directions within the Study Area, respectively. It can be seen that the number of rearend crashes by far exceed any other crash types. The next highest number of crash types is the sideswipe crashes. Both these are mainly attributed to congested conditions and vehicles making lane changes. Both conditions are exasperated with the opening of the Express Lanes. 51 P age

57 Figure 34: I 95 northbound mainline summary of total crashes by type Figure 35: I 95 southbound mainline summary of total crashes by type 10.3 Crash summary before and after Express Lanes As mentioned before, the Express Lanes became functional in January of 2015 and the three year crash data from 2012 through 2014 does not include information once they opened. Hence, additional data was requested for A four month period raw crash data was received by the study team and Table 18 lists a summary of comparison of the crash data before and after the Express Lanes opened. Based on the predicted crashes, it can be expected that the number of crashes would go up with the increase in congestion and queues due to the Express Lanes. 52 P age