ADOT, Flagstaff starting bridge widening project over I-40

Project will widen Fourth Street bridge, improve safety and traffic flow

PHOENIX – In partnership with Flagstaff, the Arizona Department of Transportation is starting a project this week to improve traffic flow and add capacity for bicycles and pedestrians where Fourth Street passes over Interstate 40.

The Fourth Street bridge, which is currently one lane in each direction, will be replaced with a wider bridge offering two lanes in each direction, a center turn lane and a protected path for bicycles and pedestrians on one side and a sidewalk on the other. 

ADOT will use an accelerated bridge construction technique that basically slides precast bridges into place to reduce the time needed to complete the improvement and minimize delays for residents of Flagstaff’s east side and I-40 drivers. 

In addition to the improvements at Fourth Street, this project includes a resurfaced bridge deck and repairs to the pavement approaches to the Butler Avenue bridges over I-40.

The work is scheduled to be complete by winter. 

Flagstaff is funding half of the cost of the project while also paying for project enhancements such as bridge aesthetics. The new bridge will also connect the Flagstaff Urban Trail System across the interstate. ADOT will be administering the project.

Drivers should be aware of restrictions while work occurs. Fourth Street will be narrowed to one lane overnight throughout the project, with flaggers directing traffic. Drivers on I-40 can expect single-lane closures in one direction at a time on nights and weekends throughout the project.

In midsummer, the project will require a 17-day full closure of Fourth Street over I-40 to remove the old bridge and slide the new bridges into place. There will also be a full closure of Fourth Street over two weekends during the project. ADOT will send notice in advance of these closures.

Excavation work is scheduled to begin Wednesday, April 1. Residents should expect construction-related noise around-the-clock at various times throughout the project.

For more information, visit azdot.gov/projects and click on North Central District.