Exit 12 Scoping Study and Final Design, Interstate I-89/Rt 2A Improvements


Williston, Vermont

Scoping Study. Engineering investigations and scoping study to explore alternatives for improving traffic movement on and adjacent to Interstate 89, particularly the southbound off ramp and extending along VT 2A to the intersection with US Route 2. Site concerns included excessive queuing of cars on southbound I-89 due to inadequate intersection capacity and traffic movement along VT 2A to US 2. The study followed the VTrans Project Development Process including close coordination with VTrans, the regional Chittenden County Metropolitan Planning Organization (CCMPO), Town of Williston, and FHWA.

Final Design. Design and environmental services through contract documents for improvements to the I-89 Exit 12 southbound off-ramp and the intersection with VT 2A. The selected alternative from the scoping study was the addition of a left turn lane onto the off-ramp to improve safety conditions on ramp. In addition, new loop detectors were placed on the ramp close to the intersection, as well as at the beginning of the ramp, just off the mainline. The loop detectors at the beginning of the ramp are connected to a “Ramp Traffic Stopped Ahead When Flashing” sign and flashing beacons on the mainline when the ramp is backed up.

Other improvements included guardrail replacement, new roadway signs including new overhead sign assembly, and other incidental items. In addition, plans included details for a new concrete pad to be placed on southbound I-89 north of Exit 12, to be used in the future for an amber alert dynamic message sign. All design services were completed in accordance with VTrans standards using MicroStation/InRoads. Coordination was conducted throughout the project development with VTrans.

  • Exit 12

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