Donlon Road Realignment

The heavily traveled State Route 118 often becomes gridlocked and prone to accidents with traffic turning left onto Donlon Road. The State Route 118/Donlon Road intersection was a T-shaped configuration joining State Route 118 and Somis Road (also known as State Route 34). This critical realignment improved safety at the intersection by eliminating the offset between Donlon Road and Somis Road, reducing time delays, and relieving congestion.

This $3M project moved Donlon Road 200 feet to the west to align with the existing traffic signal at the intersection of State Route 118 and Somis Road. The intersection became a standard four-way intersection with Donlon Road extending to the north, and the old intersection of Donlon Road and State Route 118 was closed. The new Donlon Road crosses over Coyote Canyon Creek where it joins the original Donlon Road. The project added longer left-turn lanes in both directions on State Route 118 and upgraded the highway intersection to Caltrans standards.

A new 30-foot by 12-foot concrete arch culvert (bridge) was constructed where Donlon Road crossed the barranca. Additional project elements involved highway widening, new roadway, new traffic signal, staged construction, reinforced concrete box culverts, utility relocation coordination, traffic control, Stormwater Pollution Prevention Plan (SWPPP) and National Pollutant Discharge Elimination System (NPDES) compliance, and driveway and curb ramp improvements. MNS provided preliminary and final design engineering services and a constructability review. During the design phase, MNS assisted in completing Design Exception Fact Sheets and coordinating the Caltrans Encroachment permit and environmental permit (401, 404, and 1601) process.