Chittenden County Regional Planning Commission (CCRPC) established the I-89 Exit 12B Alignment Study to examine alternative alignments for a new interchange along Interstate 89 in South Burlington, Vermont. Beyond supporting economic development and employment growth in the Chittenden County metropolitan core, the new interchange was identified for study to provide:

• Local and regional mobility and connectivity to the South Burlington and Williston employment centers;
• Improve access to the Burlington International Airport and Vermont Air National Guard facilities;
• Enhance connectivity between US Route 2, Vermont Route 116, and Vermont Route 15; and
• Enhance access to the planned South Burlington City Center.

RSG collaborated with local, regional, state, and federal officials to develop a series of future traffic scenarios based on the development potential of the surrounding land use with consideration for the provisions of the Metropolitan Transportation Plan. Using these scenarios, RSG utilized the county transportation planning model to develop the lane configuration required for a variety of interchange configurations, including a traditional diamond interchange and single point urban interchange (SPUI). The resulting alternatives were analyzed for traffic performance, cost, and environmental impact, with two viable alternatives proceeding forward with a financing study to identify funding for an Environmental Impact Statement.