I-84 Garrity Boulevard Interchange Widening and Realignment

Document Type

Student Presentation

Presentation Date


Faculty Sponsor

Sondra Miller


The existing I-84 - Garrity Boulevard interchange alignment in Nampa, Idaho is currently composed of two structurally deficient bridges with piers dividing travel lanes on the underpass intersection. Further, the interchange has reached its maximum capacity to accommodate traffic volumes, causing significant delays in the area. Our senior design team was tasked with redesigning the Interstate and underpass interchange—which includes the roadway alignments and bridge structures—to meet current and future traffic volumes. We have designed replacements for the two existing structurally-deficient bridges on I-84, widened the Interstate from two lanes to three lanes, and realigned the underpass. These design elements will increase efficiency and accommodate increased vehicle capacity, functionality, accessibility and safety.

A Single Point Urban Interchange (SPUI)—similar to those found in Ada county at the Vista Avenue, Meridian Road, and Ten Mile Road interchanges—has been designed for the Garrity Boulevard interchange. One, single-span bridge will replace the two existing, multiple-span, structurally-deficient bridges. This eliminates the need for piers on Garrity Boulevard and increases safety, while allowing for widening of I-84. We have developed a construction staging plan to ensure Garrity Boulevard and I-84 remain open throughout construction, with minimal service interruptions.

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