Big blankets vs. 405 night noise

Demolition work on the Sunset Bridge over the 405 Freeway will take place within a massive cocoon of sound blankets—some 30 feet long and suspended from cranes. Others will be draped from the back side of the bridge, while additional blankets will encase concrete barriers around the site as the south side of the bridge is dismantled piece by piece on six consecutive nights.

The sound absorption blankets—all 6,000 square feet of them—are a bit of “pre-emptive mitigation” that officials hope will help muffle some of the expected noise from the project, which, after weeks of prep work, is about to enter the bridge demolition phase on July 23.

“We’re basically encircling the site with sound blankets,” says Devon Cichoski, Metro’s community relations manager on the project to add a 10-mile northbound carpool lane to the 405 Freeway, along with other improvements. “The idea is you kind of encase the bridge in these sound blankets and less noise is escaping into the community.”

Nighttime construction noise is allowed up to 86 decibels, as measured 50 feet from the site.

“Could it still be loud with all that stuff up? Absolutely,” Cichoski says.

So people with urgent noise complaints—or other emergency issues—are encouraged to call the project’s hotline number, (213) 922-3665.

Operators (well, Metro community relations staff) really will be standing by, Cichoski says. After-hours callers will be connected to a line that provides the cell phone number of that night’s on-call representative. Callers with more routine comments or questions can leave a message. The hotline also offers a recorded rundown on each day’s lane and ramp closures.

For a look at all the planned freeways and street closures—and recommended detours—during the Sunset Bridge demolition work, check out this construction notice and attached map.

The Sunset Bridge is the first of three bridges over the freeway that will be demolished in sections and reconstructed in new-and-improved form during the course of the project. (The others are at Skirball Center Drive and Mulholland Drive.)

After the south side of the Sunset Bridge is rebuilt—which should take about 10 months—the process will be repeated on the north side. The bridge will have four lanes open to traffic during construction—two in each direction.

Read our earlier story about the Sunset Bridge work here.