ORINDA -- The Caldecott Tunnel's new fourth bore opened to traffic early Saturday, providing the first expansion since 1964 of the often congested gateway between Contra Costa and Alameda counties.
Caltrans opened the $417 million bore between Orinda and Oakland around 4:25 a.m., with California Highway Patrol crews leading the first cars through the tunnel.
Having all four bores open gives motorists four lanes in each direction permanently for the 160,000 vehicles a day that pass through it.
Previously, Caltrans had switched the direction of the middle bore twice a day, exasperating motorists who had to weave and merge when their side of Highway 24 narrowed from four to two lanes.
Saturday's transition was seamless and there were no traffic issues. One of the first motorists was none other than Golden State Warriors guard Stephen Curry, who tweeted a picture of the tunnel and said he was "hyped" for the opening.
Money for the $417 million fourth bore included $194 million from the federal American Recovery and Reinvestment Act, $124.6 million from Contra Costa County Measure J sales tax for transportation, $50 million in Bay Area bridge toll money, $20 million in state congestion funds, $19 million in state highway funds and $11 million in federal highway funds.
The fourth bore primarily will benefit motorists driving in the reverse commute direction -- eastbound in the morning from Oakland and westbound in the afternoon.
But the fourth bore will provide some travel benefits round the clock because it has a 10-foot-wide shoulder for stalled or crashed cars or emergency vehicles to use without blocking traffic. None of the older three bores have a traffic shoulder.
The fourth bore also has extensive safety features, including seven escape tunnels that connect to the third bore.
An invitation-only ribbon cutting was held Friday afternoon, but there will be no ceremony for the general public because of the limited space near the tunnel openings, Caltrans said.
Contact Denis Cuff at 925-943-8267. Follow him at Twitter.com/deniscuff.