The US 6 & Post Boulevard intersection in Avon, Colorado, serves as a vital connection point for residents, visitors, businesses and property owners in a high-volume mountain corridor. Prior to this project, CDOT recognized safety and operational efficiency of the existing roundabout needed to be improved. Poor geometry, unclear lane assignments, and lack of visibility at pedestrian crossings led to a pattern of frequent vehicle-to-vehicle crashes, conflicts between vehicles and pedestrians and a high number of close calls.
High crash rates, driver hesitation, and unpredictable movements created safety concerns for all users. Recognizing the need for a long-term solution, CDOT Region 3 selected Stolfus & Associates, Inc. as the lead consultant to reimagine the intersection. Using CDOT’s Context Sensitive Solutions framework, we engaged stakeholders, analyzed crash data, and evaluated multiple geometric design alternatives. Each option was carefully weighed against safety performance, operational efficiency, multimodal access, constructability, maintenance requirements, and potential community impacts. The result was a clear choice: a modified single-lane roundabout that provided a compact, streamlined design that outperformed multi-lane alternatives in every key category. The final design addressed the most pressing safety issues head-on. Geometric corrections calmed traffic and improved entry deflection, slowing vehicles to safer speeds. Simplified lane assignments reduced driver confusion and eliminated unnecessary decision points.
Pedestrian and bicycle safety was prioritized through single-lane exits, fewer crossing locations, ADA-compliant curb ramps, and rectangular rapid flashing beacons (RRFB’s) supporting access to the heavily used multimodal trail on the north side of US 6. Several innovations were introduced to maintain safety and control costs. The east leg pedestrian crossing was eliminated, removing a major conflict point and avoiding the cost of an additional RRFB, while preserving overall connectivity. Retrofit strategies were used to avoid major structural reconstruction of the nearby bridge, including creative grade adjustments to tie into the existing reinforced sidewalk. Truck aprons were carefully designed to accommodate large vehicles without sacrificing traffic calming benefits.
Stolfus advanced the project from scope initiation on September 26, 2022, to advertisement on November 2, 2023, on schedule and on budget. Construction was completed on July 11, 2025, at a total cost of $4.3 million, $1.1 million below the original $5.4 million estimate, with $3.29 million allocated to Stolfus’ design services.
The redesigned US 6 & Post Boulevard Roundabout has transformed a crash-prone, confusing roundabout into a safe, efficient, and user-friendly gateway for all travelers. It stands as a model for mountain corridor communities, demonstrating how thoughtful single-lane roundabout design can solve complex safety challenges, maintain operations at an acceptable level, support multimodal access, and deliver lasting value.
