How might the Standiford/99 interchange be rebuilt? Modesto starts exploring options
Modesto will spend about $7 million examining possible upgrades to the busy Standiford Avenue interchange on Highway 99.
The City Council voted 7-0 on Tuesday, April 4, for a contract with WMH Corp., an engineering firm based in San Jose. It will study traffic patterns, design options and environmental impacts over the next 39 months.
Modesto has funding to cover this step, but it is still seeking money for detailed engineering and construction, city spokeswoman Diana Ruiz-Del Re said by email.
The cost was roughly estimated at $108 million in 2020 by the Stanislaus Council of Governments, which oversees transportation funding in the county. The contract with WMH will help pin this down, along with the timeline and funding sources, Ruiz-Del Re said.
A similar process is planned for the Briggsmore Avenue interchange, a mile to the south. It has even more traffic than Standiford, and especially convoluted routes for drivers. StanCOG pegged its cost at $118 million in 2020.
When the mall was new
The Standiford interchange dates to the 1970s, when the Vintage Faire Mall was the only major retail complex in northwest Modesto. The bridge over 99 had one lane each way to accommodate the moderate traffic back then.
That area later drew big-box retailers, housing and other traffic generators on and near Standiford and Sisk Road. The Standiford bridge got more lanes to handle the load.
The interchange “was constructed incrementally in response to changing demands and available funding over time,” a staff report to the council said. “Now deficiencies are such that a complete overhaul is necessary to maintain flows into the future.”
The report said the rebuilt interchange would have to mesh with the 99 widening envisioned by the California Department of Transportation. The highway now has three traffic lanes each way but could add a fourth at some point.
A lot going on there
The engineers will have a tight space to work in. Sisk is a highway frontage road, with four lanes of sometimes heavy traffic. An electrical substation sits on the northwest corner of Standiford and Sisk. The interchange crosses over freight tracks with frequent trains. Altamont Corridor Express passenger service could arrive as soon as late 2026.
The Standiford redo happens amid a changing philosophy about road planning. Engineers for decades have emphasized motor vehicles over people on foot or bicycle. Caltrans now seeks “complete streets” in the projects it funds.
The public will be able to comment as WMH studies the options, including different stages of the environmental study. The contract is for $6.45 million, but it could grow by $645,000 if additional services are needed.
WMH was one of five firms to bid on the contract. The council approved it without discussion.
