Background

Interchange configuration, coupled with heavy traffic volumes, caused traffic to back up beyond ramps and into driving lanes on this segment of I-15. Limited sight distance obscured oncoming traffic for approaching drivers, increasing potential for high-speed, rear-end crashes at this Idaho interchange that was operating over capacity.

Project Details

Horrocks designed improvements to widen ramps and added a second right-turn lane to allow more vehicles to enter the intersection. A pre-cast pedestrian tunnel was designed and placed under the off-ramp to reduce pedestrian exposure to vehicles. Horrocks engineered designs for roadway, earthwork, drainage, structures, signaling, guardrails, sidewalks, signage, pavement markings, and work zone traffic control.

Outcomes

Horrocks led as prime consultant on this interchange. After construction, traffic queue lengths and overall congestion have been significantly reduced. New and proper signage and pavement markings have reduced last-minute lane-changes, and pedestrian improvements now provide a safer route for bicyclists and pedestrians to navigate the structure.

Awards:

Idaho Business Review, Top Project in Transportation, 2022 

American Council of Engineering Companies (ACEC) Idaho, Engineering Excellence Award, 2022 

American Society of Civil Engineers (ASCE) Southern Idaho, Project of the Year, 2022 

American Society of Civil Engineers (ASCE) Region 8, Project of the Year <$10M, 2022