Chittenden County Metropolitan Planning Organization (CCMPO) Travel Model Peer Review Report

Appendix C CCMPO TMIP Peer Review Application

FHWA Travel Model Improvement Program Peer Review Program Application

Chittenden County Metropolitan Planning Organization
December 23, 2010

Contact:

David Roberts, Senior Transportation Planning Engineer
Chittenden County Metropolitan Planning Organization
110 West Canal St, Suite 202
Winooski, VT 05404

802.660.4071 x16
droberts@ccmpo.org
www.ccmpo.org

1. CCMPO Peer Review Request Introduction

The Chittenden County MPO (CCMPO) is the federally designated Metropolitan Planning Organization (MPO) for the Burlington, Vermont metropolitan area. CCMPO was established in 1983 and currently encompasses Chittenden County, Vermont as the MPO's planning area. The region is a smaller-sized urban area with approximately 105,000 residents in the urbanized area as of the 2000 census. CCMPO is the only MPO in the state of Vermont.

CCMPO has devoted substantial resources to transportation modeling since the late 1980's to support planning analyses for long range and corridor study plans. CCMPO is currently nearing completion of an updated model to a 2005 base year which will be a daily model with hourly assignments. Recent model improvements have focused on updated housing and employment data for the 2005 base year, updated household survey information for trip generation characteristics (CCMPO was an add-on for the 2009 National Household Travel Survey), daily travel representation (from an AM and PM peak hour only model), and refined mode choice algorithms.

These specific refinements were selected to retain confidence in this planning tool and better position the region if we go out of attainment with the National Ambient Air Quality Standards (NAAQS). The County is very close to the current ozone non-attainment threshold. Desire for policy sensitivity to global warming issues also contributed to model refinements.

CCMPO has additional funding set aside to continue advancing the regional transportation model in our current FY2011 Unified Planning Work Program (UPWP) and will soon begin work on our FY2012 UPWP which will go into effect on July 1, 2011.

The proposed peer review will be an excellent means to assess CCMPO's existing model system and provide recommendations for our ongoing model updates in order to maximize limited resources. Of particular interest are suggestions related to multimodal modeling of mixed use centers in smaller urban areas and the potential advantages and difficulties associated with moving to an activity-based modeling system.

2. The Chittenden County Region

Chittenden County has about 155,000 people and 95,000 jobs as of 2010. The MPO's sister agency, the Chittenden County Regional Planning Commission (CCRPC) recently approved a 2035 population forecast of 205,000 - about 1.1% annual growth. Burlington is the largest city in the region with approximately 40,000 people. The University of Vermont, IBM, and Fletcher Allen Health Care are among the largest regional employers. Table 1 below includes a summary of employment in the County.

Table 1: Chittenden County 2008 Employment by Industry

Interstate 89 is the only interstate highway passing through the county and runs from the Canadian border to the north through Chittenden County and then heads southeast to Montpelier and southern New England. A regional map, including major transportation facilities, is included as Figure 1 below.

Figure 1: Chittenden County Transportation System Map

The regional Annual Vehicle Miles of Travel (AVMT) reported by the Vermont Agency of Transportation in 2009 was approximately 1.5 billion VMT. The model area is comprised of 335 internal traffic analysis zones (TAZ) and 17 external stations.

3. CCMPO Model Background

Chittenden County transportation modeling history dates back to the late 1960's. CCMPO has managed the regional transportation model for many years with ongoing updates and refinements reflecting new data and planning techniques. Model applications have included several regional transportation plans and corridor studies along with smaller area studies, including traffic impact studies for large development projects.

The modern history of CCMPO's basic model framework dates to 1993 when an AM and PM peak period model was introduced with two significant changes from previous Chittenden County models. First, mode choice was incorporated to allow explicit modeling of bus, rail, and non-motorized transportation. Second, the 1993 model included an integrated Land Use Allocation Module (LUAM) which used transportation accessibility in conjunction with other factors to estimate the location of new housing and employment in the county. LUAM uses local zoning and environmental constraints to establish the maximum amount of housing and employment possible in a particular zone to constrain the amount of growth. The total amount of growth in housing and employment is an exogenous input to the model based on regional forecasts developed by the CCRPC. Another 1993 model refinement was the addition of feedback loops from assignment back to distribution and mode choice as well as from LUAM back to trip generation. The LUAM feedback provides the model structure to calculate "induced" land development as areas become more accessible with transportation projects included in future years of a model analysis.

The next significant model update was in 1998 and included base year land use reflecting 1998 conditions and a regional household travel survey to re-estimate parameters for the trip generation and trip distribution. Several TAZs were created by subdividing zones in the rural areas to allow for more detailed analysis outside the urban core. This model received an award of excellence from the national Association of Metropolitan Planning Organizations (AMPO) in 1999.

In 2005 the AM and PM peak period model was converted to use the TransCAD model platform. Previous model versions used a custom program developed by Resource Systems Group, Inc (RSG) referred to as the Integrated Transportation Model (ITM) for all steps except for assignment, which was handled with the T-Model program. The use of TransCAD introduced new capabilities for assignment using an algorithm designed to accomplish user equilibrium. RSG developed a specialized routine within TransCAD to explicitly include intersection delays in the link travel times input into the assignment.

The land use in the 2005 model was updated to 2000 base year conditions and data from the 1998 Household Survey, the 2000 Census Transportation Planning Package, and other sources was used in re-estimating model parameters. This update also included a license plate survey of vehicles traveling on Interstate 89 at the county boundaries to better estimate through trips which do not have an origin or destination in the county (also referred to as external to external or E-E trips in the model).

The most recent 2008-2010 CCMPO model updates have followed a two phase process following a competitive consultant selection process. This work is now nearing completion - Phase I of the update was completed approximately one year ago and included updating the base year housing and employment data to 2005 and a transition to a daily model with hourly assignments. The previous 1993-2005 models only represented AM and PM peak hours. The transition to a daily model allows more detailed analysis of air quality issues associated with transportation while still retaining the capability to examine peak period travel demand. Phase II of this update included re-estimation of several model parameters following receipt of the 2009 National Household Travel Survey (NHTS) Vermont add-on data funded by CCMPO, VTrans, and the University of Vermont Transportation Research Center. Several additional refinements were made in support of CCMPO's long range transportation plan update currently underway.

All of the current model functions are coded in TransCAD GISDK scripts and can be made available to reviewers following receipt of a model release agreement prepared by CCMPO. More detailed information on the model is available in the draft model documentation prepared by CCMPO's consultant, RSG, a copy of which is attached to this application.

4. Peer Review Issues of Interest

CCMPO's ongoing model improvements have supported a variety of planning initiatives over the past 20 years. The organization intends to continue supporting our planning efforts and member communities with the best tools available for transportation and land use analysis.

Specific items of interest for the proposed peer review include the following:

1. Are there additional techniques we should consider in modeling mixed housing and employment land use areas which are designed to support additional non-motorized and transit use?
2. Are there recommendations for improving air quality and climate change modeling procedures? We are currently in attainment, but our policy makers have expressed significant interest in these issues.
3. The model includes a significant number of External-Internal and Internal-External trips into and out of the County. How should we prioritize areas for inclusion if the model geography were to expand outside the County boundary? Should we consider greater integration between the VTrans statewide modeling software and CCMPO's regional model?
4. CCMPO has a license for the PTV suite of the VISUM modeling program and VISSIM micro-simulation software. We would like to use this for corridor level analysis in conjunction with our existing TransCAD regional model and would be interested in recommendations regarding the general interaction between regional models and microsimulation tools as well as specific thoughts regarding the use of TransCAD and PTV software.
5. Should / how can the effects of increased travel costs (e.g. gas prices) be better implemented in the model?
6. We currently represent light, medium, and heavy truck freight in the regional model using procedures from the 1996 FHWA Quick Response Freight Manual ^[1]. Are there refinements to the quick response techniques we should consider for our region?
7. RSG has used Chittenden County as a research test case for implementing the DaySim activity-based model. Should the MPO consider transitioning into an activity-based or tour-based model?
8. Review and recommendations regarding land use forecasting tools, including the existing Land Use Allocation Module (LUAM) included in CCMPO's current model as well as the potential for UrbanSim and other tools.
9. Recommendations on visualization techniques and performance measures for better communications to stakeholders.
10. Any additional improvements CCMPO should consider to maintain a model consistent with current best practices.

5. Peer Review Administrative Details and Scheduling

CCMPO staff is mindful of the resources and scheduling difficulties associated with in-person peer review processes. To this end we would propose initiating a virtual peer review which could be completed over the course of two to three webinar-like sessions.The intent is for this to remove potential barriers to participation for panelists, decrease costs, and still provide thoughtful reviews to assist in determining future model investments.

If the TMIP staff agrees this approach merits consideration we could discuss additional details on how to accomplish this.We do not have specific panelists in mind at this point in time and would welcome assistance from TMIP or Volpe Center staff regarding participants in our process.

CCMPO's model consultants, Resource Systems Group, will be available to support the peer review.In addition, we have approximately $5,000 in funding available to support a review process which could be spent on small stipends for reviewers and/or potential travel costs if TMIP staff feels a virtual review would not provide adequate discussion opportunities.

We would like to initiate the peer review process as soon as possible in the new year. We will be drafting our work program for FY2012 in the early part of next year and would like to have the peer review results available to integrate into this process.

Please contact David Roberts on the CCMPO staff with any questions or responses to this application.

[1] http://ops.fhwa.dot.gov/freight/publications/qrfm2/index.htm