Smart Growth Twin Cities
Regionally calibrated 4D's capture travel effects of strategic
planning visions

The Smart Growth Twin Cities study developed Smart Growth planning policies and strategies for the entire Minneapolis/Saint Paul region. One of the key benefits intended from the Smart Growth concepts was a reduction in vehicle travel within the region. 4D concepts were used to produce Smart-Growth-sensitive travel forecasts comparing the long-range effects of the Current Trends Scenario to two alternative Smart Growth scenarios.

Metropolitan Council's elaborate regional travel models fulfill their purpose of forecasting macroscopic travel patterns and changes in demand for major transportation facilities. However, enhancements are needed to enable the models to reflect the parcel-level planning necessary for the Smart Growth Twin Cities study. Enhancing the models involved:

• Analysis of the recent regional Travel Behavior Inventory to ascertain specific current relationships between neighborhood land use density, mix, and urban design, and the number of vehicle trips and vehicle miles generated by neighborhood households.

• A synthesis of data from over 40 studies on relationships between built environment and travel demand for urban areas throughout the United States .

• Investigation of the regional model's native sensitivity to changes in local land use density, diversity, design, and regional accessibility, and the model's average vehicle-trips-per-capita and vehicle-miles-per-capita results based on income and transit availability.

• Development of a set of regionally-calibrated 4D elasticities to enable the model to capture sensitivities to neighborhood density, diversity, design and destinations as exhibited in the regional Travel Behavior Inventory and national data synthesis.

Using the 4D-enhanced regional models, the Smart Growth Twin Cities study found that, compared with the Current Trends, the Smart Growth scenarios would:

• Reduce vehicle trips, miles and vehicle hours of travel by 9% to 15%.

• Eliminate 2 to 3 million vehicle miles daily from Twin Cities streets and highways.

• Eliminate up to 140,000 vehicle hours of travel, and up to 73,000 vehicle-hours of congestion daily.

• Generate an additional 77,000 to 118,000 transit trips daily, including up to 25,000 additional users of LRT and transitways and over 4,000 additional commuter rail patrons. Regional LRT and transitway ridership would increase by over 30%.