TOPANGA, CA — Motorists traveling through Topanga Canyon could face delays Thursday as Caltrans crews continue work on a drainage project designed to prevent mud and debris from flooding the highway during storms.
Intermittent one-lane traffic control will be in effect from 9 a.m. to 1 p.m. Thursday on Topanga Canyon Boulevard, also known as State Route 27, according to Caltrans.
The closure will occur about 1 mile south of Grand View Drive, with flaggers directing vehicles through a section of highway less than a mile long.
Crews are preparing to install an 84-inch reinforced concrete pipe beneath the roadway, replacing an existing 34-inch pipe.
The larger pipe is designed to handle increased volumes of water and mud during rainstorms, reducing the risk of debris flowing onto the highway.
To accommodate the installation, crews are reconfiguring traffic lanes so work can proceed behind concrete barriers while minimizing disruptions to motorists.
The project also includes a new drainage system and an access road for future pipe maintenance. Construction is expected to be completed around November 2026.
The improvements are part of Caltrans' ongoing efforts to repair and strengthen State Route 27 following the 2025 Palisades Fire and subsequent storms.
Caltrans urged drivers to use caution through the construction zone, particularly around blind curves where traffic may be stopped unexpectedly. Fines can be doubled in work zones.
The closure schedule is subject to change because of weather or operational conditions.
Motorists can check current traffic conditions using Caltrans QuickMap.
Sign up for free local newsletters and alerts for the
Malibu Patch
Patch.com is the nationwide leader in hyperlocal news.
Visit Patch.com to find your town today.