The soft economy continues to mean good news for the Highway 4 widening project, as the low bid for widening the road from Somersville Road to Contra Loma Boulevard has come in nearly 30 percent less than expected.

Antioch City Manager Jim Jakel announced at the City Council’s meeting Tuesday night that Walnut Creek-based R&L Brosamer Inc. submitted a bid earlier this month for about $35.7 million. According to Contra Costa Transportation Authority Director of Projects Susan Miller, the cost of the project was originally estimated at $49.7 million.

Miller said CalTrans has until Dec. 5 to accept or deny the bid. If everything goes smoothly, Miller said Brosamer has 55 days after CalTrans’ approval to start work, which will take roughly two years to complete. She added that Brosamer’s was one of 11 bids for the project.

“It was a very competitive bid,” Miller said. “I can say it did somewhat surprise me. We have been trending low.”

The highway will be widened to four lanes in each direction, including a carpool lane, from Somersville Road to Contra Loma Boulevard. Construction will include train tracks in the median for eBART connecting Antioch with the Pittsburg/Bay Point station. Jakel said Brosamer also owns the land around the planned eBART station at Hillcrest Avenue, near where the Highway 4 expansion is slated to end.

An eBART groundbreaking ceremony is planned on Oct. 29 at 10 a.m. at the Pittsburg/Bay Point station.

“I’m thrilled with the way everything is going,” Antioch City Engineer Joe Brandt said. “I think things are going very well and I hope they continue to do that.”

Right now, the area between Loveridge Road in Pittsburg and Somersville Road is being expanded by Berkeley-based O.C. Jones & Sons. Miller said the bid for that segment of construction was also low, about 28 percent below the estimated cost. The engineers’ figure for that section was $91 million, she said, and the low bid was $64.9 million.

“I didn’t expect yet another significant drop,” Miller said. “I expected it to be competitive. Are we happy? Of course.”

Construction at Loveridge Road started in June and should take about three years, Miller said. That segment will also include a reconstruction of the Loveridge Road interchange.

The widening project comes in five phases: from Loveridge Road to Somersville Road, then to Contra Loma Boulevard, A Street/Lone Tree Way, Hillcrest Avenue and ending near the Bypass. Miller said CCTA would start taking bids for the widening from Contra Loma Boulevard to A Street early next year.

The project has been estimated to cost more than $500 million, a majority of the funding coming from Contra Costa County Sales Tax Measures C and J, and should be finished by the end of 2014.