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Freeway interchange costs keep rising with delays
Service Road 99 overpass
It will be years before the city will see the start of construction for the new Service Road overpass and its new configuration. The interchange project is also costing millions more, which could complicate a 2025 construction start date. - photo by Jeff Benziger

City officials hope that construction work will begin by 2025 on the new Mitchell/Service Highway 99 interchange, which is still in the design and planning stages.

The city has been planning a new Service/Mitchell/99 interchange since 1997 and the longer the design and red tape takes the higher the costs of construction, now estimated to cost $150 million to $180 million due to inflation.

“When it first started I thought I heard it was like $90 million and now it’s doubled, $180 million,” said Associate Engineer Sam Royal with the city of Ceres.

The project consists of modifications to Mitchell Road’s connection to the freeway and a complete tear-down and rebuild of the overpass at Service Road with new connections. Currently Service Road has no freeway access but that will change with a new northbound onramp and a southbound onramp.

The new interchange design will eliminate the dangerous way motorists exit southbound 99 at Mitchell Road. The southbound Mitchell Road on-ramp and Highway 99 off-ramp cross each other, so drivers coming off the freeway must stop and wait for a break in southbound Mitchell Road traffic headed toward the on-ramp. Under the new design, southbound freeway motorists will be able to exit at Service Road and no longer at Mitchell Road. However, the existing southbound onramp at Mitchell Road will remain.

Caltrans has approved a “diverging diamond” design for the new freeway overpass at Service Road. The design requires a different footprint and the need for property acquisitions for the rights-of-way.

Royal said that approximately 14 properties must be purchased for rights-of-way. They include properties containing dilapidated housing along El Camino Avenue north of Service Road as well as some commercial properties on Brickit Court. Right-of-way acquisition will likely take 12 to 18 months and require a consultant to manage the process and could cost $11 million.

The city has only purchased two of the needed properties. The city spent $388,960 to buy 2.16 acres at 3912 El Camino Avenue located northwest of Brickit Court. The property is mostly needed for a future storm drainage basin and a portion of a future northbound onramp at Service Road. In December 2015 the city purchased a 2.46-acre parcel at 2807 E. Service Road for $700,000.

The design calls for the Brickit Court industrial area to be accessible by Don Pedro Road and not the current route via El Camino Avenue.

Currently the project is in its Plans, Specifications and Estimates (PS&E) stage – work being performed by the consulting firm of NV5 (formerly Nolte Associates). The firm has been involved with the project since its inception. The focus of the work is to protect all the ultimate right-of-way and best position the city to pursue the funding necessary to construct the project.

The PS&E is approximately 65 percent completed and should be at 95 percent by the end of October, said Royal.

“The design process is pretty intense, especially when it comes to a bridge,” he added.

Over $7 million have been spent to get the project to the current status.

The city doesn’t have anywhere near the funds required to build the project and will seek out multiple grants and federal funds.

The Stanislaus Council of Governments, or StanCOG, committed to the use of $30.74 million of Measure L tax revenue on the Ceres interchange. More funding is expected from the state and federal governments.

“Right now we’re trying to get some help from StanCOG to assist us with funding for the rights-of-way. At the same time we are working with the consultant to help us with the federal funding for the project. We have to apply for it because it’s a huge cost and StanCOG is not going to be able to help us with the entire costs so we have to ask for federal funding.”

Before the city may seek federal funds, the project needs to complete the requirements of National Environmental Policy Act (NEPA). 

Since the project’s inception in 1997, the project has moved through different hands with the changing of city personnel. Then-City Engineer Joe Hollstein kick started the project but retired in 2007, sending it to City Engineer/City Manager Toby Wells. Wells handed the project over to City Engineer Daniel Padilla who left in 2021. Royal has also been working on the project in the background and is now assisting the new city engineer, Kevin Waugh.

In a normal freeway overpass, a vehicle remains on the right side while opposing traffic comes from the opposite direction on the left. The diverging diamond flips that circulation pattern. The crossover allows for less traffic conflicts, better and increased traffic flow and better access to the freeway.

Manteca became the first city in California to employ a diverging diamond design into a freeway interchange. Ceres could be the third or fourth once it’s completed. Many states have found the design works well and are safer.

Interchange map.jpg
An overview of the Mitchell/Service/Highway 99 that is now in the design phase.