Chengxin Dai PE Western ITE Conference Multimodal microsimulation analysis to compare performance of alternatives Develop useful performance measures in overcapacity conditions Study NEED I5 ID: 799470
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Slide1
Slide2Innovative Performance Evaluation Matrix for Solving Urban Freeway and Interchange Congestion
Chengxin Dai, PE
Western ITE Conference
Slide3Multimodal microsimulation analysis to compare performance of alternatives
Develop useful performance measures in overcapacity conditions
Study NEED
Slide4I-5
Crossroads of Portland freeway systems
150,000 AADT in four-lane cross-section at the pinch point
1,100 feet between each interchange
Critical for job and economic generators
Study Area
I-5 Broadway/Weidler
Interchange
Moda
Center
Slide5Study Area
Arterial Network
Broadway & Weidler
Moda
Center Area
Multimodal facilities
Moda
Center
Broadway St
Weidler St
Williams Ave
Vancouver Ave
Flint Ave
Winning Way
Slide6A: No-Build
1 vs. 2 lane SB I-84 flyover
B: Auxiliary Lane
1 vs. 2 lane SB I-84 flyover
C: Single Braid
1 vs. 2 lane SB I-84 flyover
D: Double Braid
1 vs. 2 lane SB I-84 flyover
A1
A2
B1
B2
C1
C2
D1
D2
Future Alternatives
Slide7Traditional MOEs:
LOS, V/C, Average Travel Time,
Brainscan Chart, Percent of Unmet Demand, etc.
Not particularly useful in heavy congestion
Proposed MOEs:Travel Time ReliabilityLane by Lane SpeedEmergency Braking
Performance Measures for congested CONDITIONS
Slide8Travel Time Reliability
The less variation from the median, the more reliable the travel time.
Use Vehicle Record data (second-by-second) sorted into northbound and southbound travel routes.
New performance measures
Slide9Lane-by-Lane Speed Chart
Compare speeds between scenarios
New performance measures
A1
B1
Slide10Emergency Braking Events
Emergency braking threshold
≥
14.8 fps
2 AASHTO Green Book (2011) emergency braking rate Emergency Braking data obtained from Vissim Vehicle Records
New performance measures
Emergency Braking Events
vs. Crash Data
Heat Map Production
(Hot Spots)
Safety Performance Prediction
for Alternatives
Slide11Existing ODOT Crashes vs.
Existing Calibrated VISSIM Results
Pearson’s correlation coefficient:
r
am
=0.56
r
md
=0.95
r
pm
=0.73
Slide12Visualize high risk sections
High concentration of emergency braking at:
Southbound Entry
Southbound between I-405 merge and Broadway off-ramp
Southbound
Braking Density Heat Maps
Future No Build 5-6 p.m.
Going Ramps
I-405
Broadway/
Weidler
I-84
Slide13Emergency Braking event
Future PM Southbound Event Analysis
Adding two-lane flyover improves the safety.
North of Broadway: all the “build” scenarios reduce
emergency
braking events by more than 60%.
South of Broadway: only braid options reduce
emergency
braking events.
Overall significant reductions in emergency braking for all the build options
Slide14Operation AND SAFETY PERFORMANCE MATRIX
Slide15Select appropriate performance measures for comparative purposes
Travel time reliability & emergency braking analysis reveal details of congested facility performance.
Combination of new and traditional MOEs for congested facility evaluation
summary
Slide16Contact Information:
Questions?
Jeremy Jackson, PE (co-author)
Senior Traffic Engineer
HDR
jeremy.jackson@hdrinc.com
Chengxin Dai
Traffic Engineer
HDR
chengxin.dai@hdrinc.com
Slide17