Gilman Street will be closed through late May as Caltrans begins construction on the Gilman Street interchange at Interstate 80, or I-80.

There will be an installation of two roundabouts and a pedestrian bridge for the project, which is expected to be completed by the summer of 2023.

The project is being completed in two phases: phase one is the installation of the pedestrian and bicycle overcrossing, while the second phase, beginning in November, will include the installation of the roundabouts. There will be roundabouts on each side of the I-80.

“The purpose of the project is to increase safety and improve navigation, mobility and traffic operations on Gilman Street between West Frontage Road and 5th Street through the I-80 interchange,” an Alameda County Transportation Commission press release reads. “The project will reduce congestion, shorten queues and minimize merging and turning conflicts.”

The Gilman Interchange has seen injury collisions at rates far higher than the national average. For example, data from 2012-15 showed the eastbound on-ramp has injury and fatality rates 95% above the national average. According to the Federal Highway Administration, installing a roundabout can result in a 76% decrease in injury collisions and a 90% decrease in fatality collisions.

The interchange has also been described as a high-stress area for cyclists. The installations include the pedestrian and bicycle overcrossing over I-80, a dedicated two-way bike lane from the west end of Gilman Street to Fourth Street, and bicycle “sharrows” connecting Gilman Street to Codornices Creek, the proposal states.

Street closures will be limited throughout construction. During the first phase, there will be ramp closures on the I-80, street closures and brief one-way overnight closures of the I-80. In the second phase, there will be sporadic closures of Gilman Street, other neighboring streets and ramps but no freeway closures.

The project is currently projected to cost $75 million.