wsf emme/2 model

Murli K. Adury
Youssef Dehghani
Sujay Davuluri
Parsons Brinckerhoff Quade & Douglas, Inc.
Seattle, WA, USA
Eric Chipps
Sound Transit
Seattle, WA, USA
Project(s) Context
Microsimulation on Two Major Highway
Corridors :
» I-405 Corridor Alternatives Analysis
– Highway Capacity Expansion Alternatives to
Alleviate Congestion on I-405
» Alaskan Way Viaduct (AWV) Project
– Project to Replace and Rebuild a highway
vulnerable to earthquake
– Microsimulation to Evaluate Traffic Impacts Due
to Construction
Project Area Map
- I-405 Corridor Study
- Alaskan Way Viaduct Project
Microsimulation for I-405 & AWV - 1
- Purpose and Need
I-405 Study
» Be able to evaluate freeway capacity enhancement
elements of the preferred alternative
» 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
AWV Project
» Evaluate options for construction sequencing
» Develop traffic control plans as part of overall
mobility plan
Microsimulation for I-405 & AWV- 2
INTEGRATION was selected as
preferred microsimulation software
 INTEGRATION model to interface with
regional EMME/2 Travel Demand Model
» Obtain base highway network – freeway
and parallel arterials
» Obtain PM peak hour O-D trip tables
Microsimulation for I-405 & AWV – 3
Model Development Process
Network preparation/calibration
 Data collection
» Details of network geometry
» Signal timings
» Traffic counts
Trip table development
 Model validation analysis
 Model application
Microsimulation for I-405 & AWV– 4
Trip Table Development
Regional model produced PM peak period
vehicle trip tables for HOVs and Non-HOV
» Apply factors to convert peak period trips to peak
hour trips
Post regional modeling procedure:
» Directional 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
Microsimulation for I-405 & AWV– 5
Trip Table Development Continued
Post regional modeling procedure:
» Screenline Analysis performed on assignment from
adjusted matrix
» Utilized Traversal Matrix assignment feature of
EMME/2 to extract sub-area O-D trip tables
» Allocated and proportioned O-D trip table from
EMME/2 model to correspond to detailed zone
structure for microsimulation model
Microsimulation for I-405 & AWV - 6
Model Validation Analysis
Initial analysis indicated that study area
networks needed to be streamlined:
Prepared link-level comparisons:
» Total flow, Travel time, Speeds
» Queue length
Comparative analysis of queue build-up
against recurring bottleneck areas posted on
the WSDOT real time traffic flow map
Accomplished reasonable base year
validation results
Model successfully utilized for future year
Model Validation Analysis
- Continued -
Lessons Learned
Trips input into microsimulation from planning
models need to be adjusted to counts
Adjustment of “seed” trip table from a planning
model is better than synthesizing O-D trips for
Useful features of EMME/2
» Can use Demand Adjustment Macro
» Can use matrix manipulation techniques to extract
sub-area matrices and to proportion trips to
detailed zone structures
Demand Adjustment for Transit Trips
Analysis Motivation
Sound Transit (ST) to build light rail (LRT)
Requirement of agreement between Federal
Transit Adminstration and ST is :
» To maintain model databases representing
conditions before and after the (LRT) project
“Before” Conditions model circumstances:
» No current transit onboard survey data being
» Link and route-level transit passenger counts by
time of day being available
Transit Components Map
Sound Transit Model History
Sound Transit (ST) EMME/2 model:
» Initially developed in 1992 to produce more
accurate route-level ridership forecasts
» Incremental using comprehensive transit
onboard survey data
» Relies on the regional 4-step model for
external factors such as change in
demographics, congestion & travel costs
» Updated recently to reflect 1999 transit
service levels and transit travel patterns
Matrix Adjustment Process
-Initial Steps
Updated transit network reflecting
service levels for fall of 2002 – over 400
 Performed transit network calibration
» Compared line times from EMME/2 model
against scheduled (actual) line times
» Detailed verification of line headways,
operating hours and miles
Matrix Adjustment Process
- Continued 
Relied on the methodology developed
by Heinz Spiess (DEMADJT.MAC)
» Minimization of difference between
estimated and observed link volumes on
each route
» Travel patterns in seed matrix not changing
more than necessary
Identified transit passenger counts
Matrix Adjustment Process
- Continued 
Extracted and processed appropriate data
from the Automated Passenger Count (APC)
GIS database
» Counts by time period
» Counts on over 200 links representing over 300
directional transit route at heavy load segments
» Used complementary vicinity count locations to
avoid under- or over-representation
» Achieved convergence after 10 iterations
Validation Analysis Results
Validation Analysis Comparison
» System-wide
» Screenline
» Route-level
» Travel patterns – before & after matrix
Rigorous Peer Review and Verification
of Counts Used
Summary Conclusions
Matrix adjustment for transit is a viable and
cost effective option when:
» Seed matrix is not too old and initially developed
from rich survey data
» Study area should have relatively good transit
» Availability of a well-calibrated transit network
» Availability of accurate and adequate counts data,
counts should be analyzed and understood
» Availability of multi-path transit assignment

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