TRB 2016 Blue Ribbon Committee
16th National Transportation Planning Applications Conference

Strategic Plan for the New Connecticut Statewide Model

Corresponding Author: Thomas Rossi, Cambridge Systematics, Inc.

Presented By: Thomas Rossi, Cambridge Systematics, Inc.


For many years, the Connecticut Department of Transportation (DOT) used a statewide travel demand model that was completed in the early 1990s. Since then, it was recalibrated several times using recent data, but it was never truly updated. The statewide model used what were at the time state-of-the-practice procedures, but both modeling methods and the needs for various planning studies changed significantly since then.

To address the need to update the model, DOT initiated a process to design a new statewide model that addresses modern planning needs and considers the unique geography and demographics of the state. The model needs to be able to address many types of analyses, including:

• Project evaluation, including projects analyzed in transportation plans and alternatives analysis

• Transit investments

• Regional and corridor planning

• Air quality conformity analysis

• Road pricing/managed lanes

• Coordination with economic forecasting modeling

• Effects of climate change and environmental issues

• Alternate land use scenarios

• Travel to and from areas outside the state, especially commuting to the New York City area

• Truck/freight modeling

• Demographic trends

• Equity analysis

• Local planning by agencies in Connecticut

DOT’s model design process used a consultant team to present options for model structure and application and convened a peer review to advise on the model features that would help them meet their objectives. The resulting model design plan includes a three-phase process for the new statewide model:

1. For the short term, a state of the practice four-step trip based model has been developed. This uses a conventional aggregate modeling approach typical of four-step models.

2. In the medium term, the model will be enhanced to use a disaggregate application approach. A synthetic population generator will be introduced to provide the means to simulate individual trips made by Connecticut residents. Recently collected household survey data will be available to update the model.

3. In the long term, the model will be converted to use an activity based approach.

The presentation will describe the planning process for the statewide model update and how other agencies could benefit from a similar strategic approach to designing and phasing model development to address planning needs.


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