Caldecott Bore 2 closes overnight Oct. 1

Eastbound SR-24 drivers will lose one of two tunnel bores on Thursday, Oct. 1, when Caltrans closes Caldecott Tunnel Bore 2 for electrical equipment replacement.

The closure runs from 10 p.m. Thursday, Oct. 1, to 4:30 a.m. Friday, Oct. 2, according to a Caltrans District 4 press release. Crews will replace an uninterruptible power supply (UPS) unit and electrical breakers and perform routine maintenance inside the bore.

All other Caldecott bores will stay open in both directions during the work. Changeable message signs will guide drivers through the area, but Caltrans warned that travelers should expect delays and allow extra travel time.

The schedule is weather-dependent and could shift.

More closures ahead

Thursday's shutdown is the first in a string of overnight Caldecott closures stretching into mid-October. A separate Caltrans schedule lists these additional 10 p.m.–4:30 a.m. closures for flat-jack testing, saw-cutting and maintenance:

Monday, Oct. 5, and Oct. 12: Bore 2, eastbound SR-24
Tuesday, Oct. 6, and Oct. 13: Bore 1, eastbound SR-24
Wednesday, Oct. 7: Bore 3, westbound SR-24

At least one bore in each direction will remain open during each of those closures, Caltrans said.

Larger Caldecott rehabilitation planned

The overnight work comes as Caltrans prepares for a larger rehabilitation of Bores 1, 2 and 3. That project is tentatively set to begin construction in fall 2026 and wrap up by fall 2029, according to the agency's project page.

The scope includes repairing cracked concrete, addressing rust and water damage in tunnel walls and ceilings, upgrading electrical and lighting systems, and installing new jet fans and a sprinkler system. An independent consultant, WSP, found that Bores 1, 2 and 3 rank among the state's top priorities for ventilation upgrades based on fire-smoke risk.

Caltrans has not said whether Thursday's electrical work is part of that larger contract or a separate maintenance action.