MATRIX ADJUSTMENT MACRO (DEMADJ.MAC AND
DEMADJT.MAC) APPLICATIONS:
SEATTLE EXPERIENCE
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
program
 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
applications
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
microsimulation
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
available
» 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
routes
 Performed transit network calibration
analysis

» 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
locations
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
adjustment

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
coverage
» 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
capability