Vermont Agency of Transportation (VTrans) Statewide Travel Model Peer Review Report
Peer Review Session 1: The Vermont Travel Model
- History of the Model
- Model Form & Function
- Update to 2009-2010 Base Year
- New 2035 Forecast Year
- Summary of Model Uses
- Potential Specific Improvements
- Questions for the Peer Review Panel
History of the Model
- Before 2003
- SAS Model Manager 2000 platform
- TRANPLAN Network
- 2003 - 2007
- Updated to base-year 2000 (forecast-year 2020)
- Transition to CUBE Voyager platform
- New roadway links added
- Minor adjustments to trip-generation coefficients and centroid connectors
- After 2007
- Update to base-year 2009 - 2010
- Update to forecast-year of 2035
- Other changes and improvements
Estimating Trip Productions and Attractions Flowcharts
Allocating Origins and Destinations Flowcharts
Assignment Flowchart
Update to 2009-2010 Base Year
- Updates to Input Data
- Households by TAZ: 2010 U.S. Census
- HH Size / No. of Workers Cross-Class by Town: 2005 - 2009 American Community Survey
- Employment: 2009 Employment Data from the Vermont Department of Labor and the Bureau of Economic Analysis
- Updates to Input Parameters
- 2009 National Household Travel Survey
Input Parameters Updated
- Regression Factors for Trip Rate Table
- Home-Based Trip Rates for Trip Rate Table
- Regression Equations for Trip Attraction and Non-Home-Based Trip Production
- Vehicle Occupancies by Purpose
- Trip Distribution Equations by Purpose for Trip Distribution
Summary of Changes to Input Parameters
Purpose |
Vehicle Occupancy Rates |
I↔E
Distributions |
Home-Based Trip Rates |
Internal Trip Distributions |
Avg. Trip Length (min.) |
% of Trips |
Existing |
New |
Existing |
New |
Existing |
New |
Existing |
New |
I-I |
I↔E |
I-I |
I↔E |
HBO |
1.56 |
1.74 |
1.75 |
1.85 |
38% |
21% |
↔ |
18.6 |
20.5 |
34% |
35% |
HBSHOP |
1.37 |
1.74 |
1.48 |
1.93 |
17% |
15% |
↑ |
20.8 |
17.4 |
14% |
21% |
HBW |
1.15 |
1.74 |
1.13 |
1.05 |
30% |
9% |
↓ |
21.8 |
20.9 |
25% |
13% |
NHB |
1.39 |
1.74 |
1.51 |
1.78 |
13% |
55% |
|
14.5 |
19.1 |
21% |
31% |
Variable |
Existing βs |
New βs |
NHB |
HBW |
HBSHOP (Urban) |
HBSHOP (Rural) |
HBO |
NHB |
HBW |
HBSHOP (Urban) |
HBSHOP (Rural) |
No. of HHs |
0.297 |
|
|
|
1.143 |
0.89 |
|
|
|
Retail Jobs |
1.143 |
1.450 |
4.115 |
6.660 |
1.179 |
2.56 |
0.59 |
4.74 |
5.06 |
Manufacturing |
0.668 |
|
|
|
|
|
Non-Manuf. |
1.722 |
|
|
0.41 |
|
|
Government |
2.450 |
|
|
0.86 |
|
|
Primary School |
1.485 |
|
|
|
|
|
University |
1.485 |
|
|
|
|
|
Purpose |
Vehicle Occupancy Rates |
I↔E
Distributions |
Home-Based Trip Rates |
|
Avg. Trip Length (min.) |
% of Trips |
Existing |
New |
Existing |
New |
Existing |
New |
Existing |
I-I |
I↔E |
I-I |
I↔E |
HBO |
1.56 |
1.74 |
1.75 |
1.85 |
38% |
21% |
↔ |
18.6 |
20.5 |
34% |
HBSHOP |
1.37 |
1.74 |
1.48 |
1.93 |
17% |
15% |
↑ |
20.8 |
17.4 |
14% |
HBW |
1.15 |
1.74 |
1.13 |
1.05 |
30% |
9% |
↓ |
21.8 |
20.9 |
25% |
NHB |
1.39 |
1.74 |
1.51 |
1.78 |
13% |
55% |
|
14.5 |
19.1 |
21% |
Variable |
|
|
NHB |
HBW |
HBSHOP (Urban) |
HBSHOP (Rural) |
HBO |
NHB |
HBW |
HBSHOP (Urban) |
HBSHOP (Rural) |
HBO |
No. of HHs |
0.297 |
|
|
|
1.143 |
0.89 |
|
|
|
0.67 |
Retail Jobs |
1.143 |
1.450 |
4.115 |
6.660 |
1.179 |
2.56 |
0.59 |
4.74 |
5.06 |
0.96 |
Manufacturing |
0.668 |
|
|
|
|
|
Non-Manuf. |
1.722 |
|
|
0.41 |
|
|
Government |
2.450 |
|
|
0.86 |
|
|
Primary School |
1.485 |
|
|
|
|
|
University |
1.485 |
|
|
|
|
|
Road Network Improvements
- Identified new links since 2000 and omitted links and added these to the road network
- Aligned TAZs with the CCMPO regional travel model
- Modify the model road network with modified roadways since 2000
- Updated turn penalties and corrected network connectivity errors
- Updated and corrected all roadway capacities
Data for Employment Growth Rates
- From economy.com with calculation by EDR Group for the Vermont Freight Plan:
- County-level growth rates
- By employment sector
- 2009 - 2039
- From the Vermont Department of Labor's long- term occupational projections program:
- Statewide growth rates
- By employment sector
- 2010 - 2020
- Neither is totally consistent with the sectors used in the Model
Employment Growth Rates
- Used an average to estimate growth rates by the employment sectors in the Model
- Conducted an iterative optimization to allocate new growth rates by sector and County:
- Used the average statewide growth rates by sector and the total County-level growth rates as control
- Calculated initial County-level growth rates by sector as a weighted average based on 2009 employment
- Adjusted the County-level growth rates by sector until they yielded weighted-average totals for 2035 that satisfied both the control totals
Forecast employment growth rates, 2010 - 2035
Addison |
0.9% |
-1.1% |
0.8% |
0.2% |
0.3% |
0.6% |
Bennington |
0.7% |
-1.2% |
0.6% |
0.0% |
0.3% |
0.3% |
Caledonia |
0.9% |
-0.7% |
0.8% |
0.2% |
0.3% |
0.6% |
Chittenden |
0.9% |
0.0% |
0.9% |
0.2% |
0.4% |
0.7% |
Essex |
0.7% |
-1.2% |
0.4% |
0.0% |
0.3% |
0.3% |
Franklin |
0.9% |
0.0% |
0.8% |
0.2% |
0.3% |
0.6% |
Grand Isle |
1.0% |
0.0% |
1.2% |
0.2% |
0.3% |
1.0% |
Lamoille |
1.1% |
0.0% |
1.4% |
0.2% |
0.3% |
1.1% |
Orange |
0.9% |
-0.6% |
0.8% |
0.2% |
0.3% |
0.6% |
Orleans |
0.9% |
0.0% |
0.9% |
0.2% |
0.3% |
0.7% |
Rutland |
0.7% |
-1.2% |
0.6% |
0.2% |
0.3% |
0.4% |
Washington |
0.7% |
-0.6% |
0.7% |
0.2% |
0.3% |
0.5% |
Windham |
0.6% |
-1.2% |
0.5% |
-0.3% |
0.3% |
0.3% |
Windsor |
0.7% |
-1.2% |
0.5% |
-0.2% |
0.3% |
0.3% |
Statewide |
0.8% |
-0.6% |
0.8% |
0.1% |
0.3% |
0.6% |
Data for Population Growth Rates
- From economy.com, calculation by EDR Group for the Vermont Freight Plan:
- County-level growth rates
- By population, not housing
- 2009 - 2039
- Household growth estimates were sparse and inconsistent, so households were assumed to grow in equal proportion to population
Forecast household growth rates, 2010 – 2035
County |
Growth
Rate |
Addison |
0.3% |
Bennington |
-0.1% |
Caledonia |
0.3% |
Chittenden |
0.6% |
Essex |
0.1% |
Franklin |
0.6% |
Grand Isle |
1.0% |
Lamoille |
0.8% |
Orange |
0.3% |
Orleans |
0.4% |
Rutland |
0.0% |
Washington |
0.2% |
Windham |
-0.1% |
Windsor |
0.0% |
Statewide |
0.3% |
2035 Forecast-Year Outputs
- Used growth rates to update TAZ-based characteristics
- Left parameters, rates, coefficients and roadway geometries unchanged
- Ran the Model through the assignment step to get 2035 trip table, a 2035 vehicle- trips matrix, and 2035 traffic volumes on links
Summary of Model Uses
Year 1
|
- Southeast Vermont bridge closure investigation
- Burlington area emissions analysis of 5+-axle trucks
|
Year 2
|
- Burlington-Middlebury corridor analysis for proposed I-89 Exit 12B
- Route 22A corridor analysis to support Stantec
|
Year 3
|
- Morristown By-Pass Travel Demand Project, repeating an analysis conducted in 2002
- Support to VHB on the VTrans VT-NY Intercity Passenger Rail Study
- Support to ICF International on the VTrans Greenhouse Gas Modeling Project
- Quebec Highway A-35 Extension Assessment Project
- Town of Cabot pass-through traffic flow analysis
|
Year 4
|
- Support to KFH Group on an examination of intercity bus travel by Vermonters
- Analysis of the Travel Behavior of Younger Vermonters to follow-up on the national study published by USPIRG
|
Year 5 (ongoing) |
- Agency Funding Gap Study – analysis of bridge funding shortfalls
|
Potential Specific Improvements
- Agency-wide strategic planning challenges:
- Aging and damaged infrastructure
- Changing demographics and economy
- Land use
- Stagnant and declining transportation fund revenues
- Energy goals
- Climate change, extreme weather events and associated impacts to infrastructure
- Freight movement and trade globalization
- Security needs and issues
- Resiliency to a changing world
Questions for the Peer Review Panel
- FHWA identified issues in the current model, particularly as it relates to the use of different modeling platforms. How should these issues be addressed to ensure VTrans has a credible and effective model?
- Resiliency planning has become a major focus at VTrans. Hurricane Irene caused significant damage to the state's transportation infrastructure. A major focus of our planning efforts in this area will be infrastructure design that can withstand such storms. How can VTrans use the model for resiliency planning?
- Vermont has set ambitious objectives towards the goal of reducing energy use and emissions. These included, for example:
- Keep VMT annual growth rate to 1.5% (half of the national average) or less for that portion controlled by the state.
- Increase public transit ridership by 110%, to 8.7 million annual trips by 2030.
- Quadruple passenger rail trips, to 400,000 Vermont-based trips by 2030.
- Reduce share of SOV commute trips by 20% by 2030.
- Double bicycle and pedestrian share of commute trips, to 15.6%, by 2030.
- Double ride share commute trips, to 21.4% of all commute trips, by 2030.
How can we use the model to monitor and evaluate progress towards goals/targets?
- While there will continue to be a need to evaluate an occasional highway capacity project, system preservation will dominate the work of VTrans. What role, if any, could a travel demand model have in system preservation, and possibly disinvestment?
- Performance-based planning and programming are a core component of MAP-21 requirements. How can the model assist us in developing and monitoring performance measures moving forward? Can the model play a role in an asset management system?
- VTrans is in the process of developing a fair-share methodology; with the aim of ensuring developers pay for the proportional impact triggered by development. How can we use the model to contribute to the fair-share methodology?
- Bicycling, walking, transit, and rail are important components of the Vermont's transportation system. Some of these modes, particularly bicycling and walking, are primarily local in scope. Is the State's travel demand model the appropriate scale to prioritize corridors for improvements (i.e. where to widen lanes for bicycle use)?
Potential Specific Improvements
- Seasonal component - average winter day, average summer day, and annual average day
- Tourist-travel (multi-day) component
- Freight module consisting of commodity flows between Counties and across the state boundary
- Feedback between traffic assignment and trip distribution steps
- Multi-modal travel - passenger rail, bus, and air
- Roadway grade and pavement condition for road-network links for speed and emissions estimation
- Square-footage basis for trip-generation
- Calibrating of traffic assignment sub-module with empirical speed/density data
- Improving the road-network level of detail to get more refined estimates of travel speeds, vehicle-miles of travel, and emissions
- Peak-hour travel estimates, along with the current daily travel estimates
- Developing and tracking parking supply for modeling NHB travel and ridesharing
- Breakdown of NHB trips into "NHB-Business" and "NHB-Personal"
Peer Review Schedule
Session #2
Date: Wednesday June 19
Time: 2:00 - 4:30 PM EST
Agenda: Discussion of key issues and questions, areas for improvement
Participants: All peer review attendees
Session #3
Date: Wednesday July 10
Time: 2:00 - 4:00 PM EST
Agenda: Independent panel meeting convened to assemble comments and feedback
Participants: Expert panel members, TMIP staff
Session #4
Date: Wednesday July 31
Time: 2:00 - 4:00 PM EST
Agenda: Comments and feedback presented by peer review panel to broader group
Participants: All peer review attendees
