Abilene District Traffic Signal Timing and Capacity Analysis

Size: px

Start display at page:

Download "Abilene District Traffic Signal Timing and Capacity Analysis"

Duane McDaniel
5 years ago
Views:

1 Abilene District Traffic Signal Timing and Capacity Analysis 2017 IAC Report Task-45 TransTech Lab, TechMRT Hongchao Liu, Ph.D., P.E. Jason (Bo) Pang, Ph.D. Ariel Castillo-Rodriguez, E.I.T. I

2 Table of Contents Table of Figures... II Chapter 1. Introduction Project Objectives Technical Plan Introduction to TranSync...3 Chapter 2. Signal Coordination Study Signal Coordination of S. 1 st St Signal Coordination of Treadaway Blvd Signal Coordination of N. 1 st St. and Buffalo Gap Rd Chapter 3. Signal Timing Study of Isolated Intersections Optimization of the Max Green TIA for US-83 & Buffalo Gap Rd. Interchange Appendix Optimized Offsets for the Coordinated Arterials I

3 Table of Figures Figure 1. Scope of Work...2 Figure 2 TranSync-D (Window-based) Example Interface...3 Figure 3 TranSync-M (ipad-based) Example Interface...3 Figure 4 Modeling Signals of S. 1st St.in TranSync-D...4 Figure 5 Vehicle Trajectories Before and After Optimization AM Plan...7 Figure 6 Vehicle Trajectories Before and After Optimization PM Plan...9 Figure 7 Coordinated Signals of Treadaway Blvd Figure 8 Before and After Optimization of Treadaway Blvd. - MD Plan Figure 9 Before and After Optimization of Treadaway Blvd. AM & PM Plan Figure 10 Traffic Count and Max Green for Buffalo Gap Rd. & Antilley Rd Figure 11 Traffic Count and Max Green for Buffalo Gap Rd. & Beltway St Figure 12 Traffic Count and Max Green for Arnold Rd. & Hartford St Figure 13 Traffic Count and Max Green for Arnold Blvd. & S. 7 th St Figure 14 Existing Lane Configuration of the US-83 Interchange Figure 15 Simulation Model of the US-83 Interchange in Vissim Figure 16 Design Alternative Figure 17 Design Alternative II

4 Table of Tables Table 1 Measures of Effectiveness for Signal Coordination Evaluation...5 Table 2 Before and After Optimization Comparison of the AM Plan of S. 1 st St....6 Table 3 Before and After Optimization Comparison of the PM Plan of S. 1 st St....8 Table 4 Before and After Optimization Comparison of the MD Plan of Treadaway Blvd Table 5 Before and After Optimization Comparison of the AM & PM Plan of Treadaway Blvd 12 Table 6 Before Optimization N. 1 st St. AM (7:00 9:45) Plan Table 7 Before Optimization N. 1 st St. PM (16:30 18:30) Plan Table 8 Before Optimization Buffalo Gap Rd. AM (7:00 8:45) Plan Table 9 Before Optimization Buffalo Gap Rd. PM (16:30 18:30) Plan Table 10 Performance Comparison of Alt-1 and Existing Condition Part A Table 11 Performance Comparison of Alt-1 and Existing Condition Part B Table 12 Performance Comparison of Alt-2 and Existing Condition Part A Table 13 Performance Comparison of Alt-2 and Existing Condition Part A Table 14 Existing and Optimized Offset of S.1st St Table 15 Existing and Optimized Offset of N.1st St Table 16 Existing and Optimized Offset of Treadaway Blvd III

5 Chapter 1. Introduction To improve the operation of existing traffic signal systems of multiple arterial roads, the Texas Department of Transportation (TxDOT) Abilene District has contracted the Texas Tech University Center for Multidisciplinary Research in Transportation (TechMRT) TransTech Lab (TTL) research group to optimize the signal coordination, detection systems and equipment to effectively handle traffic. It is expected that this improvement will bring existing traffic signals into up-to-date standards. This final report documents the research process and final solutions for the TxDOT IAC Task-45 project. This chapter provides an introduction and discusses the objectives of this project. 1.1 Project Objectives The overarching goal of this project is to improve the traffic operations of multiple arterial roads in the City of Abilene and bring the traffic signals into an up-to-date standard. The scope of work of this project is shown in Figure 1. In detail, the signal coordination strategies of the objective corridors are not performing reasonably well to accommodate the present traffic flow. Excessive vehicle delay and queues have been observed during peak hours. Additionally, the signal control strategies of multiple isolated intersections (not coordinated) need to be optimized as well. In order to accomplish the goal of providing appropriate solutions to the existing issues, the research team has established multiple objectives over the span of this project. 1) Evaluate the existing traffic operation and signal performance for the scope of work, including South & North 1 st St. (BI-20); Treadaway Blvd. (BU-83); Buffalo Gap Rd. (FM-89) and 19 isolated intersections. 2) Optimize the signal timing and coordination plans of all 56 intersections stated above 3) Field implementation of new plans 4) Perform necessary fine-tuning 5) Perform before-and-after analysis 6) Document research findings and solutions 1

6 Figure 1. Scope of Work 1.2 Technical Plan Two different approaches of techniques have been used in this project to address to the distinct issues related to either the signal coordination of the major corridors or the timing plan of each individual intersection. As one of the critical objectives of this project is to thoroughly evaluate the coordination performance of a large number of traffic signals, in order to dramatically improve the efficiency and accuracy of the engineering work on the coordinated signals, an innovative software package named TranSync, which is dedicatedly designed for solving a wide range of signal coordination related issues, is used by the research team with the permission of TxDOT Abilene District. Details of the TranSync software package will be introduced in the following section. On the other hand, for the purpose of optimizing the existing signal timing plans of the isolated intersections in the scope, traditional engineering approaches have been used, including field data collection of approach-based traffic volume and signal timing design in Synchro. 2

1.3 Introduction to TranSync TranSync is a revolutionary tool for systematic diagnosis, optimization and performance measurement of coordinated signals without the need of traffic volume data.

(Figure 3), which uses ipad for data collection and performance analysis.

7 1.3 Introduction to TranSync TranSync is a revolutionary tool for systematic diagnosis, optimization and performance measurement of coordinated signals without the need of traffic volume data. The TranSync software package is composed of a Windows-based TranSync-D (Figure 2) for optimization of coordination plans and managing signal timing data; and mobile device based tool TranSync-M (Figure 3), which uses ipad for data collection and performance analysis. TranSync-D only uses vehicular trajectory data collected by TranSync-M and the signals time-space diagram for coordination optimization. Figure 2 TranSync-D (Window-based) Example Interface Figure 3 TranSync-M (ipad-based) Example Interface As traffic volume data are no longer needed in this process, it leads to great cost reduction while significantly improves the efficiency compared to the traditional work flow by using Synchro. Additionally, the optimization outcome had been proved very satisfying with many other similar projects. 3

8 Chapter 2. Signal Coordination Study This chapter documents the problems and corresponding solutions regarding the signal coordination of four major arterial roads in the scope of work, respectively are South & North 1 st St. (BI-20); Treadaway Blvd. (BU-83); Buffalo Gap Rd. (FM-89). 2.1 Signal Coordination of S. 1 st St. The S.1 st St. is the business road of I-20 that runs through the city of Abilene, the traffic flow of this corridor is relatively higher than the other three. To identify existing issues and provide appropriate solutions for this corridor, the following work have been done by the research team. 1. Modeling all 10 intersections along S.1st Street (from US-83 West Ramp to Oak St., 3.2 miles, as shown in Figure 4) in the TranSync software suite 2. Evaluating the existing coordination condition 3. Optimizing the offset of each signal 4. Field implementation of new plans 5. Before and after comparison analysis Modeling S.1st Street (3.2mile) in TranSync-D Figure 4 Modeling Signals of S. 1st St.in TranSync-D In detail, to evaluate the current coordination condition, multiple two-way road trips along this corridor have been done by using TranSync-M to collect the vehicle trajectory data, which 4

9 would be imported to TranSync-D and matched with the time-space-diagram of the existing timing plan for the purpose of a thorough bandwidth optimization. Next, the second round of trajectory collection was carried out after the implementation of the optimized results (offset and phasing sequence) onsite. Finally, the conditions before and after the optimization are fully compared in TranSync-D in terms of the various measures of effectiveness (MOE) to demonstrate the improvements of the signal coordination. Details of the comparative before and after analysis is introduced in the following section. To demonstrate the improvements of the signal coordination of all Time of Day (TOD) plans, the before and after conditions are summarized and compared in the form of vehicle trajectory on the time-space-diagram in this section. Before starting the comparative analysis, all TOD plans (original and optimized) are coded in TranSync-M and then carefully observed and modified onsite to ensure a precise match of the two systems. Note that the measures of effectiveness (MOE) used in the evaluation of the signal coordination of each corridor are presented in Table 1. Table 1 Measures of Effectiveness for Signal Coordination Evaluation MOE Bandwidth (sec) Attainability (%) Average Travel Time (sec) Average Travel Speed (mph) No. of Stops Remark The amount of time available for vehicles to travel through a system at a determined progression speed The ratio of the total bandwidths to critical (with minimum green time) phase lengths for each of the directions The average value of the travel time of each direction for all trips made The average value of the travel speed of each direction for all trips made Average number of stops for all road trips 5

10 The results of the comparative before/after analysis of coordination for each TOD plan of the S. 1 st St. are presented below. I. AM Plan (7:00-8:45) Note that based on the simulation in the TranSync-D and a careful field observation, the existing phasing sequence is determined to be most appropriate as for the traffic flow patterns of both directions of this corridor. Therefore, the offset is the only parameter that have been optimized for the coordination and is summarized in Appendix A. Table 2 illustrates the quantitative comparison of the coordination performance before and after the analysis for the AM timing plan. Note that all of the MOEs mentioned previously were thoroughly analyzed to ensure the accuracy of the comparison. Table 2 Before and After Optimization Comparison of the AM Plan of S. 1 st St. Direction Average Average Bandwidth Attainability No. of Travel Time Travel (sec) (%) Stops (Sec) Speed (Sec) Before EB Optimization WB After EB Optimization WB Per the data revealed in Table 2 as well as the filed observation, the coordination of both directions of S. 1 st St. at AM peak hours were considered moderate, no major congestions or traffic platoons were observed. The main reason of this condition is the light traffic volume on the side (minor) streets, which accordingly causes the green time to be reassigned earlier to the major street phase (Early Return to Green, ERTG) frequently. Despite the fact that no major delay or traffic queue had been caused by the current coordination plan, there are still a large room to optimize it and reduce the average travel time and the number of stops. In specific, the westbound coordination has a bandwidth of 8 seconds before optimization, which means that after motorist enters the arterial (from the first signal), the common green time of each signal left for them is only 8 seconds; if they can t start the trip by 6

falling into the range of the 8 seconds, it s very likely that they have to stop multiple times when travelling along the corridor in lack of the compensation of early return to green.

6 times higher than before, even without early return to green on the major street.

11 falling into the range of the 8 seconds, it s very likely that they have to stop multiple times when travelling along the corridor in lack of the compensation of early return to green. However, after optimizing the offsets in TranSync-D, the bandwidth of this direction has been increased to 21 secs, which suggests that the chance of a non-stop trip is 1.6 times higher than before, even without early return to green on the major street. In order to better illustrate the improvement of the coordination, the time-space-diagram (TSD) embedded with the vehicle trajectories before and after optimization is presented below. (a) Before Optimization AM Plan (b) After Optimization AM Plan Figure 5 Vehicle Trajectories Before and After Optimization AM Plan 7

12 As can be seen from Figure 5, the improvement of the WB bandwidth (shown in blue) is very obvious after optimization. In addition, the vehicle trajectory in Figure 5-(a) is depicted as a dotted line, which indicates that the vehicle progression is not so smooth when compared to the trajectory in Figure 5-(b) after optimizing the offset, speed adjustment or lane change behavior happened frequently during the trip. II. PM Plan (16:30-18:30) Note that the traffic volume is relatively low during the mid-day peak hours along S. 1 st St. than the other peak hours, accordingly, the coordination does not need to be further tuned. In this section, the coordination analysis is presented for the PM peak hour plan. The quantitative comparison of the coordination condition is presented in Table 3. Table 3 Before and After Optimization Comparison of the PM Plan of S. 1 st St. Average Average Bandwidth Attainability No. of Direction Travel Time Travel (sec) (%) Stops (Sec) Speed (Sec) Before EB Optimization WB After EB Optimization WB As can be seen from Table 3, the coordination at the PM peak hours is generally worse than the AM peak hours. Consequently, the improvements are much more significant after optimizing the offset. In detail, the bandwidths increased 70% for the EB progression, and the number of stops dropped 0 and 1 for the EB and WB direction, respectively. Figure 6 illustrates the improvements in the form of TSD with vehicle trajectory. It s obvious to see that the testing vehicle stopped twice for the trip before optimization, at the intersection of Sayles Blvd. and Willis St., respectively. 8

(a) Before Optimization PM Plan (a) After Optimization PM Plan Figure 6 Vehicle Trajectories Before and After Optimization PM Plan 2.2 Signal Coordination of Treadaway Blvd.

In specific, the coordination of this corridor is split into two sections, namely the north section and the south section. Coordinated signals in the north section include: N. 7 th St., N.

13 (a) Before Optimization PM Plan (a) After Optimization PM Plan Figure 6 Vehicle Trajectories Before and After Optimization PM Plan 2.2 Signal Coordination of Treadaway Blvd. The signal coordination of Treadaway Blvd. is discontinuous among all the signals. In specific, the coordination of this corridor is split into two sections, namely the north section and the south section. Coordinated signals in the north section include: N. 7 th St., N. 10 th St. and N. 13 th St., while the south section contains S.7 th St., S. 11 th St. and S. 14 th St. The reason of this discontinuance is that the signals of the closely-spaced two intersections of Treadaway & S. 1 st St and N. 1 st St. are operated by using overlaps instead of standard NEMA operations to 9

Figure 7 Coordinated Signals of Treadaway Blvd Generally speaking, the signal coordination of the North Section is better than the South Section for both the AM and PM plans.

14 accommodate the unique geometric designs of this area, thus, they cannot be incorporated into the coordination system with other signals. The objective signals along this corridor are displayed in Figure 7. North Section: N. 13th St. to N. 7th St. South Section: S. 7th St. to S. 14th St. Figure 7 Coordinated Signals of Treadaway Blvd Generally speaking, the signal coordination of the North Section is better than the South Section for both the AM and PM plans. In detail, the MD plan for the North Section, as well as the AM & PM plans for the South Section can be further improved. The other plans for the two sections are in a good condition with the existing offset. In addition to the coordination, a couple of signal operation related issues were observed for some of the signals in this system and were resolved immediately. 1) A five-second drift was detected for the coordination of the South Section for all TOD plans, which is resolvable by adjusting the timing plan in the server. 2) An early termination of the SB Through green phase at S. 14 th St. was detected. The reason account for this issue is the incorrect setting of the pedestrian phase in the controller. 10

Note that the AM and PM coordination plans of South Section are identical, and the traffic volumes are also similar, therefore, only the MD and PM plans are tested in this study.

15 Note that the AM and PM coordination plans of South Section are identical, and the traffic volumes are also similar, therefore, only the MD and PM plans are tested in this study. The results of the comparative before/after analysis of coordination for the MD and PM plan of the Treadaway Blvd. are presented below. I. MD Plan (9:00-16:00) for the North Section Table 4 Before and After Optimization Comparison of the MD Plan of Treadaway Blvd. Direction Average Average Bandwidth Attainability No. of Travel Time Travel (sec) (%) Stops (Sec) Speed (Sec) Before NB Optimization SB After NB Optimization SB As can been in Table 4, the NB coordination along Treadaway Blvd. is obviously worse than the SB coordination. The testing vehicle stopped once during this NB trip (when entering the system). Additionally, the bandwidths are highly unbalanced between the two directions (as shown in Figure 8), which significantly reduces the efficiency of the coordination and increases the number of stops for the NB traffic. Accordingly, the purposes of the optimization are to balance out the green bands of both directions and reduce the number of stops to zero. (a) TSD before Optimization MD plan 11

16 (b) TSD after Optimization MD plan Figure 8 Before and After Optimization of Treadaway Blvd. - MD Plan II. AM (7:15 8:45) & PM (16:00-18:00) Plan for the South Section In general, the coordination issue of the South Section is similar to the North Section. The NB offsets can be largely improved for a smoother traffic progression. As can be seen in Table 5, the NB bandwidth is only 6 seconds while the SB bandwidth reached 20 seconds. What s more, the number of stops for both directions were unsatisfying, the testing vehicle stopped twice within only three signals. Table 5 Before and After Optimization Comparison of the AM & PM Plan of Treadaway Blvd Before Optimization After Optimization Direction Average Average Bandwidth Attainability No. of Travel Time Travel (sec) (%) Stops (Sec) Speed (Sec) NB SB NB SB After optimization, the bandwidths have been increase by 550% and 120% for the NB and SB progression, respectively, together with a significant drop for the number of stops. In addition, the TSD of the before and after analysis is provided as follow to intuitively present the improvements. 12

Per the results of multiple road test, it has been determined that the existing coordination plans of N. 1 st St. and Buffalo Gap Rd.

17 (a) TSD before Optimization AM & PM plan (a) TSD after Optimization AM & PM plan Figure 9 Before and After Optimization of Treadaway Blvd. AM & PM Plan 2.2 Signal Coordination of N. 1 st St. and Buffalo Gap Rd. Per the results of multiple road test, it has been determined that the existing coordination plans of N. 1 st St. and Buffalo Gap Rd. are both in very good status because of the low traffic volume of either the main corridors or side streets, no further modifications of the offsets are required. The test results of the AM and PM coordination plans are presented in the following tables for the two corridors. 13

18 N. 1 st St. AM Plan Before Optimization Table 6 Before Optimization N. 1 st St. AM (7:00 9:45) Plan Direction Average Average Bandwidth Attainability No. of Travel Time Travel (sec) (%) Stops (Sec) Speed (Sec) EB WB Table 7 Before Optimization N. 1 st St. PM (16:30 18:30) Plan Average Average N. 1 st St. Bandwidth Attainability No. of Direction Travel Time Travel AM Plan (sec) (%) Stops (Sec) Speed (Sec) Before EB Optimization WB Table 8 Before Optimization Buffalo Gap Rd. AM (7:00 8:45) Plan Average Average N. 1 st St. Bandwidth Attainability No. of Direction Travel Time Travel AM Plan (sec) (%) Stops (Sec) Speed (Sec) Before NEB Optimization SWB Table 9 Before Optimization Buffalo Gap Rd. PM (16:30 18:30) Plan Average Average N. 1 st St. Bandwidth Attainability No. of Direction Travel Time Travel AM Plan (sec) (%) Stops (Sec) Speed (Sec) Before NEB Optimization SWB

19 Chapter 3. Signal Timing Study of Isolated Intersections This chapter documents the signal timing optimization and traffic impact analysis for the isolated intersections and interchanges which are not operated in coordination mode. In detail, all atgrade intersections listed in the scope of work are currently operated in fully-actuated uncoordinated mode, there are no fixed cycle length or splits for those signals. Therefore, the focus of such signals has been decided to be the optimization of the Max Green time for each actuated phase based on the present traffic volume. On the other hand, a Traffic Impact Analysis (TIA) has been done to the interchange composed of Buffalo Gap Rd., S. Clack St. and Industrial Blvd. Current traffic operation in this location is prone to congesting because of two main reasons: 1) high traffic volume of each approach; 2) inefficient geometric design. The research team has conducted a thorough simulation of the current traffic operation of this intersection and proposed two alternative solutions to mitigate the congestion. 3.1 Optimization of the Max Green As mentioned previously, the Max Green times of four isolated intersections operated in a fullyactuated uncoordinated mode has been optimized in Synchro. To this end, the research team has conducted an approach-based data collection of the traffic volume for all four intersections. Note that not all uncoordinated intersections in the scope of work are selected for such an optimization, because no signal-related problems have been identified for a large number of these intersections. Therefore, only four of them (Buffalo Gap Rd. & Antilley Rd.; Buffalo Gap Rd. & Beltway St.; Arnold Blvd. & Hartford St.; Arnold Blvd. & S. 7 th St.) were selected for an optimization on considering the higher traffic volume and some minor congestions with the turning traffic. The approach-based traffic volume of the intersections and the optimized Max Green times are presented as follows. 15

20 I. Buffalo Gap Rd. & Antilley Rd. Figure 10 Traffic Count and Max Green for Buffalo Gap Rd. & Antilley Rd. II. Buffalo Gap Rd. & Beltway St. Figure 11 Traffic Count and Max Green for Buffalo Gap Rd. & Beltway St. III. Arnold Blvd. & Hartford St. Figure 12 Traffic Count and Max Green for Arnold Rd. & Hartford St. 16

It is important to note that, although this interchange looks like a conventional diamond interchange, the TTI four-phase operation is not applicable because the Industrial Blvd.

21 IV. Arnold Blvd. & S. 7 th St. Figure 13 Traffic Count and Max Green for Arnold Blvd. & S. 7 th St. 3.2 TIA for US-83 & Buffalo Gap Rd. Interchange The interchange involved in this TIA study is composed of Buffalo Gap Rd., S. Clack St. (frontage road of US-83) and Industrial Blvd. It is important to note that, although this interchange looks like a conventional diamond interchange, the TTI four-phase operation is not applicable because the Industrial Blvd. is in fact a two-way street and eventually results in a complex signal control strategy of this interchange. According to the information provided by the traffic engineer from TxDOT Abilene District, there are currently two major issues with this interchange: 1) excessively long vehicle platoons and large delay for the NWB traffic on Industrial Blvd.; 2) significantly large delay for the NB left-turn traffic from S. Danville Dr. onto Industrial Blvd. The main reason accountable for both issues is the use of a shared lane for the NWB through, left-turn and right-turn traffic on Industrial Blvd. Note that the Mall of Abilene and several other shopping centers are located on the west side of Buffalo Gap Rd. and works as a major traffic attractor, therefore, the left-turn traffic volume is very large during peak hours, and in lack of a channelized right-turn lane, traffic of all approaches have to queue up on Industrial Blvd. (especially on the right-most lane) and block the left-turn progression from S. Danville Dr. controlled by stop sign. Moreover, the NB right turn traffic from Buffalo Gap Rd. to Industrial 17

Blvd. is channelized and basically is operated in a free flow mode, thus works as another contributor to the excessive delay of the left-turn traffic on S.

To resolve these problems, the researchers conducted a thorough simulation of the traffic operations in this area in Vissim and proposed multiple solutions

22 Blvd. is channelized and basically is operated in a free flow mode, thus works as another contributor to the excessive delay of the left-turn traffic on S. Danville Dr. To resolve these problems, the researchers conducted a thorough simulation of the traffic operations in this area in Vissim and proposed multiple solutions based on the simulation results. The current lane configuration of this interchange as well as the simulation model in Vissim are shown in Figure 14 and Figure 15, respectively. Figure 14 Existing Lane Configuration of the US-83 Interchange Figure 15 Simulation Model of the US-83 Interchange in Vissim 18

Design Alternative-1 In this alternative design, the researcher has proposed to add an exclusive right-turn lane to channelize the WB right-turn traffic on Industrial Blvd, thus to provide more

23 Design Alternative-1 In this alternative design, the researcher has proposed to add an exclusive right-turn lane to channelize the WB right-turn traffic on Industrial Blvd, thus to provide more queueing space for the adjacent through and left-turn traffic; in the meantime, signalize the NB right-turn traffic on Buffalo Gap Rd. (bridge section) to provide a longer gap for the traffic flow on S. Danville Dr. turning onto Industrial Blvd. Figure 16 depicts the schematic of this alternative. Exclusive RT Lane Signalized RT Movement Figure 16 Design Alternative-1 Per the simulation results obtained in Vissim, the maximum queue length and average vehicle delay of the WB through and Left-turn traffic on Industrial Blvd. were both decreased, however, the improvements of this low-cost design alternative didn t bring the overall LOS of both approach to a higher level, and the tradeoff of increased delay of other approach is also obvious. Detailed result comparisons between Alternative-1 and the existing condition are presented in Table 10 and Table

24 Table 10 Performance Comparison of Alt-1 and Existing Condition Part A Buffalo Gap Rd. & Industrial Blvd. Affected Movements Current Condition Max Queue Length (ft) Alt-1 Improvement Current Condition Ave. Vehicle Delay (sec) Alt-1 Improvement SB TH % 21(C) 21(C) 0.0% SB LT % 77(E) 82(F) -6.5% SB RT % 7(A) 11(B) -57% WB TH % 71(E) 57(E) 19.7% WB LT % 52(D) 49(D) 5.7% Table 11 Performance Comparison of Alt-1 and Existing Condition Part B Industrial Blvd. & S. Danville Dr. Affected Movements Current Condition Max Queue Length (ft) Alt-1 Improvement Current Condition Ave. Vehicle Delay (sec) Alt-1 Improvement NBL % % EBT WBT Design Alternative-2 (Recommended) Design Alternative-2 is proposed on considering the pros and cons of Alternative-1 and is essentially a modification of the first alternative. In this design, the researchers had done a laneshift to the WB traffic on Industrial Blvd and provided an additional exclusive left-turn lane, because the former simulation results indicate that the current traffic volume had exceeded the capacity of the lane configuration. In detail, the existing receiving lane for all EB traffic on 20

25 Industrial Blvd has been converted to an exclusive left-turn lane for the WB traffic, furthermore, all EB traffic turning onto Industrial Blvd. are going to use the existing left-most lane and share it with the NB right-turn traffic (signalized). Figure 17 presents the schematic of this design alternative Lane-shift of the WB Traffic Figure 17 Design Alternative-2 Table 12 Performance Comparison of Alt-2 and Existing Condition Part A Buffalo Gap Rd. & Industrial Blvd. Affected Movements Current Condition Max Queue Length (ft) Alt-2 Improvement Current Condition Ave. Vehicle Delay (sec) Alt-2 Improvement SB TH % 21(C) 21(C) 0.0% SB LT % 77(E) 78(E) -1.0% SB RT % 7(A) 11(B) -57% WB TH % 71(E) 39(D) 45% WB LT % 52(D) 40(D) 23.1% 21

26 Table 13 Performance Comparison of Alt-2 and Existing Condition Part A Industrial Blvd. & S. Danville Dr. Affected Movements Current Condition Max Queue Length (ft) Alt-2 Improvement Current Condition Ave. Vehicle Delay (sec) Alt-2 Improvement NBL % % EBT WBT As can be predicted, Design Alternative-2 is very likely to cost more than the first one, however, the improvements it brings are also satisfying. The max queue length and the average delay were both dropped significantly without sacrificing the operation of other approaches. Detailed comparisons are shown in Table 12 and Table 13. Overall, other than a potential higher cost and a longer construction period, Design Alternative-2 outperforms Design Alternative-2 in many aspects, such as average vehicle delay and queue length, therefore, this it is highly recommended by the research team. 22

27 Appendix Optimized Offsets for the Coordinated Arterials Table 14 Existing and Optimized Offset of S.1st St. S. 1st St. Existing Offset (sec) Optimized Offset (sec) AM MD PM AM MD PM US-83 West Ramp US-83 East Ramp Pioneer Dr Leggett Dr Willis St Shelton St Sayles Blvd Grape St Butternut St Oak St Table 15 Existing and Optimized Offset of N.1st St. N. 1st St. Existing Offset (sec) Optimized Offset (sec) AM MD PM AM MD PM Pioneer Dr Leggett Dr Westwood Dr Willis St Mockingbird Ln Shelton St Graham St Grape St

28 Table 16 Existing and Optimized Offset of Treadaway Blvd. Treadaway Blvd. Existing Offset (sec) Optimized Offset (sec) AM MD PM AM MD PM North Section N.7th to N. 13th N.13 th St N.10 th St N.7 th St South Section S.7th to S. 14th S.7 th St S.7 th St S.7 th St

0-6920: PROACTIVE TRAFFIC SIGNAL TIMING AND COORDINATION FOR CONGESTION MITIGATION ON ARTERIAL ROADS. TxDOT Houston District

0-6920: PROACTIVE TRAFFIC SIGNAL TIMING AND COORDINATION FOR CONGESTION MITIGATION ON ARTERIAL ROADS TxDOT Houston District October 10, 2017 PI: XING WU, PHD, PE CO-PI: HAO YANG, PHD DEPT. OF CIVIL & ENVIRONMENTAL