1. Integrated Performance Impact Analysis –Linking Travel Modeling and Economic Modeling
Transportation Planning Applications Conference
Sheldon Harrison
Senior Associate
May 16, 2017

2. Overview of GDOT Study
Evaluate potential performance impacts of 11 strategic highway infrastructure investments across the state
Travel time impacts
Economic impacts
Compare 2030 E+C to 2030 Build to communicate aggregate benefits across the investment package
Required integrated set of existing travel modeling platforms across the state and customized economic forecasting tool

3. Priority Projects I-285/I-20 East and West Interchanges
I-285 East and West Wall Express Lanes
SR 400 Express Lanes
I-285 Top End Express Lanes
I-85 North Widening (north of Atlanta)
I-75 Truck Lanes
I-16 Widening
I-16/I-95 Interchange

4. Use Existing Tools to Leverage Planning Investments
Make effective use of existing tools, given time constraints
Apply existing travel demand models where projects were proposed
Statewide model
Savannah model
Atlanta region model
Apply GDOT economic forecasting tool – part of Economic Impacts Study
Integrate the travel demand and economic modeling tools
Statewide model – report results by REMI region as input to econ tool
Savannah/Atlanta– geographic stratifications by county
Convert outputs to standard input purposes for economic analysis tool

5. Trip Purposes for Economic Tool
Tool requires 4 economic trip purposes
Commute
Leisure
Business
Trucks
Separate demand models require different approaches
Statewide models
Large geographic area
Typically have additional purposes
MPO models
Smaller geographies
Often stratified by time of day
Less likely to have assignments by trip purpose

6. Purpose Assumptions – Statewide Model
Purposes
Long Trips
HBW
HBO
NHB
External Passenger & Trucks
Short Trips
HBW
HBO
NHB
Commercial Vehicles
Commute: All HBW trips
Leisure: Most Short Non-work trips
Business: Most of the Long and External trips

7. Purpose Assumptions – Contd.
Commute
100 % Long and Short HBW
Business
5% short HBO, NHB, IE/EI
40% long HBO, NHB, IE/EI, EE
Leisure
95% short HBO, NHB, IE/EI
60% long HBO, NHB, EI/IE, EE
Truck
All Freight truck and Commercial trips

8. Purpose Assumptions – Savannah
Trips by purpose
Unavailable on assigned links
Ideally
Rerun assignment using trip purposes as assignment class
Practical Solution
Split assignment trip table
Use same assumptions as GSTDM
Apply derived trip purpose distribution to number of trips on each link

9. Trip Table Manipulation
Take Trip table by purpose
Calculate trip purpose proportions
HBW
HBO
NHB
IE/EI
Apply earlier assumptions to link to economic purposes
Leisure
Commute
Business

10. Purpose Assumptions – ARC 4-Step Model
Trips by Purpose
Unavailable on assigned links
ARC has Time-of-Day assignment
AM, MD, PM, NT
Otherwise, same procedure as Savannah

11. Customized Cube Scripts

12. Travel Model Inputs for Economic Tool
Key measures needed for Economic Analysis
VMT
VHT
Average Delay per Vehicle
Each needs to be available by
Specific geography
REMI in the case of Georgia
Economic trip purpose
Commute, Leisure, Business, Trucks

13. Georgia REMI Region Geography

14. Travel Model Script Output Files
Outputs
VMT
VHT
Average Delay
Repeat for four economic purposes

15. VB Macro to Automatically Populate Sheet with TDM Outputs

16. Daily Model Inputs to Economic Tool

17. Time of Day Model Inputs to Economic Tool

18. Economic Tool Interface

19. Project Metric Summary
Transportation Metric
2010
2030 Open to Traffic Year
Base
E+C
Build
% Change
Total (Auto+Truck) VMT
225,387,610
275,408,883
274,384,027
-0.4%
Total (Auto+Truck) VHT
8,184,732
11,455,393
11,232,647
-2.0%
Average Vehicle Delay (mins)
0.2
0.32
0.31
-5.4%
Total Vehicle Hours of Delay
1,555,398
3,085,044
2,927,560
-5.1%
Source: Impact Analysis for Roadway Improvements
Cambridge Systematics, Inc. May, 2016

20. Project Summary Source: Impact Analysis for Roadway Improvements
Cambridge Systematics, Inc. May, 2016

21. Economic Impacts
Aggregate Economic Impacts  
Permanent Jobs (units)
13,660
Income (millions of $)
$1,081
GSP (millions of $)
$2,466
Transportation Costs - Auto (millions of $)
-$34
Transportation Costs - Truck (millions of $)
-$68
Package of evaluated projects predicted to have positive effects
Job creation
Increased economic activity
Reduction in transportation costs
Other detailed economic metrics also available from tool
Source: Impact Analysis for Roadway Improvements
Cambridge Systematics, Inc. May, 2016

22. Additional Applications of Process
Other Regions
Arkansas
Mississippi
Florida
Virginia
Kentucky
Process implemented with different modeling software
Cube
Voyager / TP+ script
TransCAD
GISDK script

23. Conclusion Streamlined process of compiling disparate model outputs
Leverage pre-existing investment in travel demand models
Used with Four Step, Activity Based, or Statewide Model
Items to consider when developing economic model
Consistent reporting of geographies
Available trip purposes from each model
Purposes in economic versus travel demand model
Use of available assignment link attributes in benefit estimation

24. Thank You
Sheldon Harrison Cambridge Systematics, Inc Other Contributors Tracy Selin Paula Dowell