BART is giving riders a heads-up that a major reconstruction project on its Antioch-Millbrae line will have a major impact on weekend trips in Contra Costa County starting this Friday night.
But the project — which will replace a mile of nearly 50-year-old rails, electrical equipment and other trackside gear near the Lafayette Station — includes a major wrinkle: two lanes of the adjacent freeway, Highway 24, will also be shut down for six separate weekends between now and late October.
And that means that drivers headed eastbound from Oakland through the Caldecott Tunnel into Contra Costa County may see some major delays on their weekend trips during the project, which begins at 11 p.m. this Friday night.
The weekend lane closures are necessary because BART needs to use a 265-ton crane to facilitate the work, which will involve lifting hundreds of 80-foot rail sections, each weighing thousands of pounds, into place. The only place to put the crane: in two left-hand lanes of eastbound Highway 24.
Both BART and Caltrans are trying to get the word out that travelers, and especially drivers, should prepare for the delays and avoid the area if they can.
"We do expect that if motorists don't take other routes, we're going to very quickly get to a 30-minute backup that will be 3 miles or more long, almost all the way back to the Caldecott Tunnel," Bart Ney, spokesman for Caltrans District 4, said Tuesday. "That's what we saw when there was a trial run of the work a couple weekends ago."
Ney said Caltrans will monitor the backup and has worked out a plan with BART if it's worse than expected.
"If we see that type of backup again, we can call into them and have them pick up half the closure" — one lane — and restore the traffic through the area," Ney said.
BART spokesman Chris Filippi said that having to reduce the closure from two lanes to one will affect the project's work schedule.
"If that happens, it will slow down the work, because we'll have to restage some of the equipment, we'll have to move things around," Filippi said.

