Simmerly Slough Bridge

An aerial shot of the worksite of the Simmerly Slough Bridge Replacement project on Friday.

An $83.6 million project to replace the outdated Simmerly Slough Bridge that connects Marysville with District 10 is underway and construction crews have made so much progress since September that managers expect the project to be completed a year ahead of schedule. 

The bridge on Highway 70 just north of Marysville no longer meets current design and seismic safety standards, and the area beneath the bridge, which fills with water during high water events, has experienced scouring due to water removing sediment around the bridge’s piers and abutments. Caltrans hired MCM Construction to do the bridge work – the same company currently in charge of building the new Fifth Street Bridge between Yuba City and Marysville. 

“The contractor is working hard to get the fill put in place before the rainy season hits,” said Cameron Knudson, project manager for Caltrans. “That’s when we are forced to quit hauling in dirt, so we are working hard to get this bridge constructed.” 

Work began at the beginning of September. The most notable change is the amount of dirt that has been hauled in to where the new bridge will be constructed. Crews have placed upwards of 150,000 cubic yards of dirt so far, with plans of placing roughly 350,000 cubic yards total. By raising the terrain, the bridge will not have to close during significant high-water events and can serve as an extra evacuation outlet from the city, Knudson said.

“We are also working on realigning Laurellen Road as part of the project, so that part of the project is getting close to being completed,” Knudson said. “Then, we’ll be getting ready to do the bridge piles and some of the foundation work for the structure.” 

The new bridge being constructed parallel to the current structure will be striped for two lanes and provide for 8-foot paved shoulders, sidewalks on both sides and a concrete barrier separating the shoulder from the sidewalk and bridge railing. It will be able to accommodate fives lanes in the future. Crews are also realigning the highway approaching the bridge on both ends. 

“The project was originally scheduled for three years of construction, but because the contractor is out there working hard – provided everything continues to go well – they anticipate finishing a year early,” Knudson said. “It’s been really great. They came in with the plan and desire to get this project done.”

As the bridge nears completion, Knudson said, motorists can expect some traffic impacts, though the plan is to maintain two lanes of traffic for the majority of the time. The hope is to complete the bridge and have it open by September 2021.

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