Highway 4 Closes East of Discovery Bay This Weekend. Every Event on the Calendar Is on the Open Side.

At 10 p.m. Friday, Caltrans will close State Route 4 between Roberts Road and the San Joaquin/Contra Costa county line, east of Discovery Bay, and keep it closed until 10 a.m. Sunday, October 25.

It's a full closure in both directions, but it only covers the stretch toward Stockton and Holt. The highway into town, the marina, and the roads west to Brentwood stay open. This weekend's Halloween events are all in Discovery Bay or west of it. The people who will feel the closure are the ones driving east, plus anyone on the Byron Road and Mountain House Parkway legs of the detour.

Thirty-six hours, east of town

The Caltrans District 10 closure notice calls this an "additional 36-hour full highway closure" of SR-4 from Roberts Road to the county line, needed for the SR-4 Delta Pavement Improvement Project. Inside the closure limits, only residents and people going to local businesses will be let through. Flaggers and message signs will direct traffic, and Caltrans expects delays of about 30 to 40 minutes.

The Town of Discovery Bay announced the closure in its own press release, which The Press picked up with the same detour and delay estimate.

The 36-hour window covers Friday night, all of Saturday and early Sunday morning. If you have a Saturday trip to Stockton or Lodi, or a drive home from the San Joaquin side, plan for the detour. If your weekend is Brentwood, the marina or your own street, the closure is somewhere you won't be going.

The detour, both ways

Caltrans publishes one loop. It takes Roberts Road, Howard Road and Tracy Boulevard on the San Joaquin side, I-205 in the middle, and Mountain House Parkway and Byron Road on the Contra Costa side. Each direction runs the loop in reverse.

Heading east from Discovery Bay:

1. Take Byron Road south to Mountain House Parkway.
2. Continue south to I-205 East.
3. Exit at Tracy Boulevard and go north to Howard Road.
4. Go east on Howard Road to Roberts Road, then north to SR-4.

Coming home westbound:

1. From SR-4, take Roberts Road south and continue west on Howard Road.
2. Go south on Tracy Boulevard to I-205 West.
3. Exit at Mountain House Parkway and go north to Byron Road.
4. Follow Byron Road back to SR-4.

Byron Road and Mountain House Parkway carry detour traffic in both directions all weekend. They are also everyday roads for Discovery Bay drivers going south toward Tracy and I-205. Detour traffic and local traffic will share them from Friday night to Sunday morning, even if you never come near the closed stretch.

Why the road is closing a fourth time

This weekend was not in the original plan. The project has already closed the same stretch three times this summer, and each closure was longer than this one.

Caltrans says the three summer closures turned up more pavement and sub-surface failures, and those failures require this extra closure to repair. In other words, crews found problems under the road surface once they opened it up.

The project covers about nine miles of SR-4 between the county line and South Whiskey Slough Road in Holt, just west of Stockton. Caltrans describes the pavement there as showing "major distress" that would keep getting worse if left alone. The work starts with digging out failed sections, followed by cold planing and an overlay. It also adds shoulder backing, approach and departure slabs, electrical work, traffic management systems, lighting and sign panels.

The contractor is Bay Cities Paving & Grinding, Inc., based in Concord, and the contract is worth $21.6 million. That works out to roughly $2.4 million per mile of highway.

What's on the open side

Here is the weekend in order. Every stop is in Discovery Bay or west of it, so none of the trips touch the closure.

Friday, October 23

• Halloween BINGO, 5 to 9 p.m. Soroptimist International of the Delta is holding its Halloween BINGO at De Luna Ranch, 7540 Balfour Road in Brentwood. Tickets are listed at $55 and include dinner. Bingo ends at 9, an hour before the highway closes at 10.
• Friday night at the marina. The Delta events calendar lists Marina Bar & Grill's usual Friday karaoke and prime rib night for October 23. Recurring specials can change, so call the restaurant before you go.

Saturday, October 24

• Fall Fun Day, noon to 4:30 p.m. Serendipity Cellars, at 1600 Chestnut St. in Brentwood, lists a family-friendly afternoon, and RSVP is requested.
• Hometown Halloween, 4 to 8 p.m. Downtown Brentwood's free community trick-or-treat event is listed by Better in Brentwood for October 24. Some older listings still show last year's date of October 25. This year's event is Saturday.
• Hard Rock Halloween, 7 to 9 p.m. Marina Bar & Grill, at 5879 Marina Road, has Lucky Dogz playing, along with a costume contest and prizes, according to the event listing.
• Live music at DB Sportsbar & Steakhouse. The restaurant at 2477 Discovery Bay Blvd. has a live music night listed for October 24. Its posted hours run 11 a.m. to 11 p.m. Thursday through Saturday.

For groceries, the Discovery Bay Safeway at 14840 Hwy. 4 is listed as open 24 hours.

The following week

The highway is open again by then, and the calendar keeps going west. On Friday, October 30, Night of the Living Loud is an all-ages, alcohol-free Halloween concert at Brentwood Community Center, 35 Oak St., from 6 to 10:30 p.m. The Press calendar lists multiple live bands, a costume contest with prizes for the top three costumes, community vendors, and voter information and resources. Advance tickets are $15 plus fees, or $20 cash at the door. DB Sportsbar & Steakhouse has more live music on November 6 and 7, from 6:30 to 10 p.m.

After Sunday morning

When the highway reopens at 10 a.m. Sunday, the work east of town isn't finished. A Delta Protection Commission bulletin sent October 6 says one-way traffic control at Old River Bridge is expected through November. Eastbound trips over the next several weeks may still mean waiting for your turn at the bridge.

Caltrans gives two different end dates. This weekend's closure notice says the 185-working-day contract started April 6 and should finish in spring 2027. The agency's project page lists a target completion of February 2, 2027. Caltrans also says its schedules can change because of weather, traffic incidents, equipment and materials, and construction problems. This weekend's closure was added after crews found more damage under the road, so check the District 10 news page before any eastbound trip this winter.

Questions about Discovery Bay, from road work to how the town's routes shape daily life, are part of the job for Danielle Campbell. If something on this weekend's map or this winter's construction schedule raises a question about your home or your plans, let's connect.