Transcript wsf emme/2 model
A PERSPECTIVE ON APPLICATION OF A PAIR OF PLANNING AND MICRO SIMULATION MODELS: EXPERIENCE FROM I-405 CORRIDOR STUDY PROGRAM
Murli K. Adury Youssef Dehghani Cathy Strombom Parsons Brinckerhoff Quade & Douglas, Inc.
Seattle, WA, USA
Project Context
I-405 Corridor Program: » I-405 was built in 70s to alleviate congestion along I-5 » Experiencing unexpectedly high high levels of congestion rate of growth from high tech sector (e.g., Microsoft) within I-405 corridor – resulting in » Undertaking comprehensive alternatives analysis
Project Area Map
Why Micro Simulation?
Be able to evaluate realty checks on capacity enhancement elements of the preferred alternative – balancing capacity needs on arterials vs. I-405 thru better diversion mechanism Be able to refine enhancement and/or modify capacity elements of the preferred alternative Be able to highlight potential deficiencies e.g., lid concept thru downtown Bellevue –
Why Integration?
WSDOT undertook a rigorous evaluation the existing micro simulation software programs of Integration most suited because of its capabilities for: » Micro simulation analysis at corridor level » Equilibrium route diversion analysis » State-of-the-art methodology analysis for traffic simulation » Being able to interface with the existing regional planning model databases
Model Development Process
Network preparation/calibration Data collection » » » Details of network geometry Signal timings Traffic counts Trip table development Model validation analysis Model application
Network Development
Included only: » » I-405 & major parallel arterials (3000 links) Major intersections (100 signalized intersections) Initially used default parameters & refined further during validation process Most difficult tasks: » » Developing a network to fit INTEGRATION limits Data input for microsimulation – lane geometry, signal data, turn pockets, physical attributes of roadway system
Trip Table Development
Regional model produced PM peak (hour) vehicle trip tables for HOVs and Non-HOVs Post regional modeling procedure: » Direction peak-hour base year counts were seeded on designated links on I-405 and arterials » Matrix adjustment macro DEMADJ.MAC
developed Heinz Spiess was used to update original matrix » Resulting O-D matrix was imported into the Integration model environment
Model Validation Analysis
Initial analysis indicated that study area network needed to be streamlined : » » Secondary arterials were removed Secondary signalized intersections were also removed Hourly counts exhibited wide variations weekdays and months: » Overall average and max/min limits were established across Attempts were made to “ optimize ” signal timing coordination
Model Validation Analysis - Continued -
Prepared summary system-wide measure: » » » » Peak-hour demand input as % of total demand % vehicles reached destinations VMTs/VHTs Total delays & stop delays Prepared link-level summaries: » » » Total flow Travel time Queue length
6000 5000 4000 3000 2000 1000 0 0
Model Validation Analysis - Continued -
Model Flow Rate vs Average Peak Hour Count (I-405 NB between SR 167 and SR 169)
90 Min Count Max Count Avg Count Model 15 30 45 60 75
Simulation Time (Time = 0 to 90 minutes)
Model Validation Analysis - Continued -
Comparative analysis of queue build-up against recurring bottleneck areas posted on the WSDOT website Performed additional network refinement accordingly Accomplished reasonable base year validation results
Model Validation Analysis - Continued -
Model Application
In I-405 EMME/2 Model » Developed 2020 network for the preferred alternative » » Prepared 2020 Travel Forecasts Developed 2020 peak-hour trip table – Prepared base year to 2020 zone-to-zone growth rates – Applied implied zone-to-zone growth rate to the base year adjusted peak-hour trip table
Model Application - Continued -
Provided insights analysis process into the alternatives Highlighted initially proposed improvement plan/conceptual design deficiencies within the project corridor Identified potential bottleneck areas Integration modeling achieved purpose its
Lessons Learned
Allow adequate time to: » Define objectives for why needing to do micro simulation and for what purpose » Identify appropriate software its limits accordingly program and Identify study area carefully for: » Boundaries » Network details (no. of links & intersections)
Lessons Learned - Continued
Assess potential interface with other tools (e.g., regional model databases, network editing, etc.) Trip matrices need to go through an adjustment process reflecting actual counts Assess data needs carefully Micro simulation consuming model is data hungry & time