One-Way Traffic Control on State Route 116 west of Guerneville, in Sonoma County for Slide Repair

Published: Jan 07, 2025

Traffic control begins early morning on Wednesday, January 8

SONOMA COUNTY - Caltrans will implement one-way traffic control on State Route 116 about a mile and a half west of Guerneville in Sonoma County during the morning of Wednesday, January 8, 2025, as part of a landslide repair project.

Portable traffic signals will control east- and westbound traffic as they take turns traveling the length of the closure, which, according to initial assessments, will be in place for approximately three months while temporary repairs are made.

On December 27, 2024, Caltrans crews noticed substantial erosion below the eastbound shoulder of Route 116 bordering the Russian River. Before long, the erosion had toppled two trees and undercut a portion of the eastbound shoulder. Work crews placed cones along the shoulder and covered it with plastic sheets to stave off further erosion. However, the erosion has advanced to a point that threatens the road and two sewer pipes within the right-of-way.

Caltrans obtained a Directors' Order, a source of emergency funding, and hired a contractor, Piazza Construction, to begin work on shoring up the slope alongside the road.

The design of a temporary or permanent retaining wall is challenging.

Typically, sheet piles would be vibrated into the earth to shore the road. However, the likelihood of damaging a high-pressure sewer line running beneath the eastbound shoulder precludes such an option.

Instead, workers will build a soil nail wall that bolsters the road by drilling horizontally below the road and inserting long, cylindrical soil nails in the holes.

A permanent retaining wall will be designed and installed sometime in the future.

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