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 rate of

growth from high tech sector (e.g., Microsoft) within I-405 corridor – resulting in high levels of congestion

» 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 and/or modify capacity enhancement 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 of the existing micro simulation software programs

Integration most suited because of its capabilities for:» Micro simulation analysis at corridor level» Equilibrium route diversion analysis» State-of-the-art methodology for traffic simulation

analysis» 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 across

weekdays and months:» Overall average and max/min limits were established

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

Model Validation Analysis- Continued -

Model Flow Rate vs Average Peak Hour Count(I-405 NB between SR 167 and SR 169)

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Simulation Time (Time = 0 to 90 minutes)

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Model

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 into the alternatives analysis process

Highlighted initially proposed improvement plan/conceptual design deficiencies within the project corridor

Identified potential bottleneck areas Integration modeling achieved its

purpose

Lessons Learned

Allow adequate time to:» Define objectives for why needing to do

micro simulation and for what purpose» Identify appropriate software program and

its limits accordingly 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 model is data hungry & time

consuming