IMPACT OF TRANSIT SIGNAL PRIORITY (TSP) ON BUS TRAVEL TIMES, LATE BUS RECOVERY, DELAY AND LEVEL OF SERVICE (LOS) Presenter: Sotonye Ikiriko 1, Deo Chimba 1 College of Engineering, Tennessee State University, Nashville TN 37209 USA 21 st June 2018
2 Introduction! Transit Signal Priority (TSP) " A strategy to Speed up Transit Vehicle Movement! Benefits " Boost Transit Movement Without undue Impact on other Road Users " Reduce Bus Bunching " Improve Transit (bus) Schedule Adherence " Reduce High Auto Dependency " Expand Mobility Choices " Improve Transit ridership " Reduce Energy consumption, green house Gases and other Pollutants
3 Principle of TSP Operation! Components " Transit vehicle detection system " Communication system " Traffic signal control system
4! Nashville is fast growing " According to Randall Gross everyday 85 people come into Nashville! High traffic congestion! Poor bus serviceability! Poor Schedule Adherence! Transit unattractiveness " According to David Hartgen only 1.5 to 2.5% of Nashville Residents use Transit Why TSP?
5 Study Corridor! Gallatin Pike corridor! 12.3 miles Long! An arterial roadway! two lanes in each direction! continuous left turn lane! 48 signalised intersections! 104 posted bus stops
6 Modelled Section of Gallatin Corridor! 1.83 Miles Long! Two lanes in each Direction! Continuous left turn lane! 9 signalized Intersection! 7 bus stops in each direction
7 Research Objectives Evaluate the impact of TSP on;! Transit operation " Bus Schedule Adherence in Terms of Late bus recovery at bus Stop level " Bus Travel Time Reduction " Mainline and Side Street Delays! Intersection Level of Service (LOS)
Methodology! Microsimulation Software Selection " VISSIM! Data collection! Origin Destination (OD) Matrix Estimation and Validation " Principle of Conservation Of Vehicles! Base Model Development in VISSIM! Base Model Calibration and Validation " Alternative Concept " TSP " VAP code: Green extension and Red truncation TSP strategies
9 Data Collection! Roadway Geometry " Intersection Layout " Lane Configuration " Bus Stop location and Types! Traffic Data " Turning Movement Count(TMC) " General Traffic Travel Time! Transit Data " Speed Profile " Bus travel Time " Boarding and Alighting Count " Ridership " Schedule Adherence! Traffic Control Data " Signal Timing and Phasing Plans
10! Corridor Geometry! Connectors Base Model Development! Urban Motorised Driving Behaviour " Wiedemann 74 car following Model! Vehicle Composition! Desired Speed Distribution! Public Transportation Stops! Public Transportation Line
Dynamic Assignment In VISSIM 11
12 Base Model Calibration and Validation! OD Matrices Calibration! Speed Calibration " Simulated and Observed Speed (PE < 5%)! Travel Time Validation " Simulated and Observed Travel Time (PE < 15%) PE=Percentage Error
13 TSP Signal Logic Implementation! Passive Priority " It allocates more green time to approaches having higher bus flow than it would for others! Active Priority " Green Extension " Red Truncation! Vehicle Actuated Programing (VAP) Code " Signal Timing and Phasing Plans
TSP Signal Logic Implementation in VAP Code Bus Detector 75m from signal Gap out Detectors Bus Detector 75m from signal Minimum Recall Detectors Bus Stop Signal Head
OD Matrix Calibration and Validation Results Estimated (Veh\hr) 1400 1200 1000 800 600 400 200 0 OD Matrix Validation y = 1.3672x - 1.9452 R² = 0.8569 0 200 400 600 800 1000 1200 1400 Observed (Veh\hr) OD Matrix Calibration 1600 Simulated (Veh\hr) 1400 1200 1000 800 600 400 200 0 y = 0.9661x - 2.1964 R² = 0.9984 0 200 400 600 800 1000 1200 1400 1600 Estimated (Veh\hr)
Impact of TSP on Main Line Travel Time 600 550 Main Line Travel Time Measurement Base Base + TSP Average Travel Time (Sec) 500 450 400 350 300 250 200 150 100 EB WB EB WB EB WB EB WB Bus Car HGV All Vehicles MainLine Vehicle Types EB= Eastbound, WB= Westbound
17 Impact of TSP on Main Line Vehicle Delay Main Line Vehicle Delay 300 Base Base + TSP 250 Vehicle Delay (sec) 200 150 100 50 0 EB WB EB WB EB WB EB WB Bus Car HGV All Vehicles Main Line Approach
Late Bus Recovery at Bus Stop Level Late Bus Recovery 400 350 Base Base + TSP 300 Lateness (Sec) 250 200 150 100 50 0 Stop 1 Stop 2 Stop 3 Stop 4 Stop 5 Stop 6 Stop 7 Stop 1 Stop 2 Stop 3 Stop 4 Stop 5 Stop 6 Stop 7 PT Line 1 PT line 2 PT lines and Bus Stops PT Line = Public Transportation Line
Impact of TSP on Side Street Vehicle Delay Side Street Delay Comparison 120 100 Base Base + TSP Vehicle Delay (Secs) 80 60 40 20 0 NB SB NB SB NB SB NB SB NB SB NB SB NB SB NB SB NB SB Alta Loma Unnamed River Gate Pkwy Cude Ln Shepherd Hills Conference Dr Intersection Approach Liberty Ln North Side 2284-2282 TN-6 SB=Southbound, NB=Northbound
Significance of TSP on Side Street Delay Group Statistics Scenario N Mean Std. Deviation Std. Error Mean Delay Base 64 48.9344 21.25447 2.65681 Base + TSP 64 55.2509 20.20847 2.52606 Independent Samples Test Levene's Test for Equality of Variances t-test for Equality of Means F Sig. t df Sig. (2- tailed) Mean Difference Std. Error Difference 95% Confidence Interval of the Difference Lower Upper Delay Equal variances assumed 0.215 0.643-1.723 126 0.087-6.31656 3.66601-13.57148 1 Equal variances not assumed -1.723 125.68 0.087-6.31656 3.66601-13.57166 1
Overall Corridor Performance In Terms of Level of Service Intersection Name Intersection Delay & LOS Base LOS Base + TSP LOS % Increase % Reduce Alta Loma 27.3 C 31.1 C 14.0 Unnamed 21.5 C 21.5 C 0.2 Rivergate 34.1 C 42.4 D 24.3 Cude Lane 21.3 C 23.3 C 9.2 Shepherd Hills 20.9 C 21.4 C 2.2 Conference Dr 24.8 C 26.1 C 5.1 Liberty 17.1 B 17.9 B 4.6 North Side 17.7 B 18.5 B 4.4 2284-2282 TN-6 8.0 A 8.0 A 0.1 All Intersection 21.4 C 23.3 C 8.0 0.1
Conclusion TSP will reduce bus travel time by about 5% to 10% Reduce Travel time for other vehicles utilizing the priority approach by about 5.8% Reduce bus delay by about 11% to 23% Reduce delay for other vehicles utilizing the priority approach by about 11.6% Reduce bus lateness by about 34.16% Increase Side Street Delay by about 15.9%
23 Thank You For Listening Any Questions?