MARTINEZ (CBS SF) – Caltrans will close state Highway 4 in Martinez overnight on Thursday and Friday for the first phase of a project intended to reduce congestion and improve safety at the highway interchange with Interstate Highway 680.

Work on Thursday will close westbound Highway 4 between Peralta Road and the Highway 680 interchange from midnight to 4 a.m. Work on Friday will close eastbound Highway 4 between Peralta Road and Pacheco Boulevard from 1 to 4 a.m.

Work, involving the removal of overhead signs, has been scheduled to minimize traffic disruption and maximize worker safety. The agency says this week’s work “will lay the groundwork for future improvements to connector ramps, improve traffic safety and enhance traffic flow.”

The interchange improvement project will widen about 4 miles of Highway 4 “in both directions between Morello Avenue in Martinez and state Highway 242 by adding a third lane in the eastbound and westbound directions to improve on-ramp and off-ramp merging,” Caltrans officials said in a news release.

Other work will include widening five structures, extending the eastbound Highway 4 carpool lane about 2 miles, installation of safety lighting, and replacement of the Grayson Creek Bridge, which will be replaced with a three-span structure that meets current state safety codes.

Additional widening and retrofit work in subsequent phases of the project will be done on nearby bridges, including inside widening of the five-span Walnut Creek Bridge, the Solano Way undercrossing and the Peralta Road undercrossing, as well as widening the inside and outside shoulders of the Pacheco Boulevard undercrossing in both directions.

Construction is expected to finish in late 2021.

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