The widening of Highway 4 in East Contra Costa County has caused increased delays on what has been identified as one of the top 10 most congested commuting corridors in the nation as well as the San Francisco Bay area’s most congested corridor, according to a Times Herald report.

 A recent study by traffic data-tracking firm INRIX saw Highway 4 jump from No. 37 to No. 10 in the U.S. rankings for highway congestion, and at least some of the blame for the jump is being pinned on the ongoing work to widen the highway from four to eight lanes from Pittsburg through Antioch.

The INRIX rankings were based on real-time data and analysis from about 4 million vehicles carrying global-positioning devices that traveled the nation's major roads, according to company spokesman Jim Bak. The study looked at additional travel time on roads during rush hour compared with when traffic was flowing freely.

The East Bay ranked as the nation's third worst region in the study.

The improvements to the highway will not be completed for at least three more years.