Highway 156 Near Oak Hills: Caltrans Advertises $75.5 Million Castroville Boulevard Interchange, Bids Due November 19

OAK HILLS / HIGHWAY 156, Monterey County — October 30, 2026. A major highway improvement along the east–west route used by drivers from Oak Hills, Prunedale and Castroville has reached a procurement milestone. The California Department of Transportation (Caltrans) lists construction contract 05-316014 for the Highway 156/Castroville Boulevard Interchange as advertised, with contractor bids due November 19, 2026. The state’s project page estimates $75.5 million in construction funding and says the new grade-separated interchange should begin major construction in spring 2027, with completion targeted for fall 2029.

Those are procurement and scheduling records, not proof that a construction contract has already been awarded, the interchange is open or that heavy interchange construction began this October. Caltrans lists utility relocation as in progress. The project lies at Castroville Boulevard and State Route 156 near Castroville, not at a new highway junction in the Oak Hills subdivision itself. Its significance to Oak Hills is the role of Highway 156 as a major route between nearby communities and the Monterey Peninsula.

What is actually changing at the intersection?

Today, the Castroville Boulevard junction is an at-grade traffic-signal intersection on the Highway 156 corridor. Caltrans proposes replacing it with an interchange that separates crossing traffic vertically, supported by roundabouts. The Transportation Agency for Monterey County (TAMC) describes three modern roundabouts, pedestrian refuges and crossings that comply with Americans with Disabilities Act accessibility standards, and improved routes connecting Castroville, nearby housing and North Monterey County High School.

The Caltrans project webpage also describes approximately 1.3 miles of ADA-compliant concrete multi-use pathway connected with the existing route over the railroad tracks from Castroville. TAMC’s July summary describes roughly a mile of Class I bike/multiuse facility. These figures come from different project summaries and may reflect a rounded route length or different segments; they should not be added together to claim a 2.3-mile new path. Detailed engineering sheets determine the final constructed length.

Why is this part of Highway 156 significant?

According to Caltrans, the existing signalized intersection has a higher concentration of collisions than the statewide average for similar intersections. As a signal that periodically stops through traffic, it can also cause queues along an important freight and tourism corridor. The proposed separated interchange aims to reduce conflicting movements, improve traffic flow and provide safer crossing facilities for people walking or bicycling.

These are the project’s stated engineering objectives; the future collision reduction cannot be measured before it is built and operating. Nor does this phase mean the entire Highway 156 West Corridor four-lane freeway vision has been funded or completed. Caltrans identifies the Castroville Boulevard interchange as a defined first phase within a broader long-range corridor program.

Where does the $75.5 million come from?

Caltrans identifies a $75.5 million construction funding package consisting of approximately $60.1 million in Senate Bill 1 Cycle 4 state funding and $15.4 million in TAMC local funding. TAMC’s July 28 announcement specifies more precise figures of $60,076,000 in state grants and $15,389,000 in local Measure X/regional development impact fee funds, for $75,465,000. The smaller numbers are a more exact agency budget presentation, not evidence of a separate additional $75 million award.

Project funding is allocated to the construction phase and may not include all costs incurred over the project’s previous design, right-of-way and utility-relocation history. A funded budget should also not be confused with the final winning construction bid; bids must be received, evaluated and awarded under applicable procedures.

The current procurement and construction timeline

The Caltrans Contracting Opportunities Portal listed project ID 05-316014 as Advertised in its District 5 records reviewed October 28, with a November 19, 2026 bid due date. The description places the work in and near Castroville, from 0.4 mile west of Castroville Boulevard to 0.3 mile east of Monte Del Lago. It lists roadway excavation, asphalt, structural concrete and new interchange construction among the types of work.

TAMC’s July 28, 2026 funding announcement listed utility relocation in fall 2026, bid advertisement in September, contract award planned for January 2027, and an estimated start of major construction in May 2027, followed by about two years of work. The Caltrans project page states the broader spring 2027–fall 2029 construction window. Schedules can change because of bidding, utilities, environmental conditions or other work; the newsworthy event here is the advertised construction opportunity, not a completed interchange.

What about current traffic restrictions?

Caltrans also issued a separate October 26 notice stating that utility crews would use one-way reversing traffic control on Highway 156 near the Highway 156/183 interchange on Tuesday, October 27, 9 a.m.–3 p.m., with work expected to wrap up by October 28. That previously announced one-day window must not be reported as an ongoing lane closure on October 30. Drivers should check Caltrans QuickMap before each journey for current controls, future utility work and any changes to the highway.

Residents along the corridor, including Oak Hills commuters, should watch for new bid award notices and future notices about construction staging. Do not assume that a roundabout is already in service or that an alternate neighborhood road will be designated as a detour without an official traffic plan.

How to follow the project

Caltrans lists project manager Chad Stoehr at (805) 550-0713 and email chad.stoehr@dot.ca.gov. TAMC identifies principal transportation engineer Javier Hernandez, telephone (831) 775-4413. For contract milestones or bid conditions, use the state’s contracting portal rather than treating a past press release as a live procurement record.

Primary sources: Caltrans — SR156 West Castroville Boulevard Interchange, location, scope, funding and schedule; Caltrans — District 5 Contracting Opportunities, advertised project 05-316014 and bid due date; TAMC, July 28, 2026 financing and construction forecast; Caltrans, dated October 27 utility traffic-control notice. Published October 30. This is an upcoming construction/procurement report; no award, opening, present-day lane closure or completed traffic improvement is presumed.

Documented corrections: California58 Newsroom.

Featured photograph: an illustrative existing highway overpass photographed by Bryan Colosky / Unsplash. It is not the proposed Highway 156/Castroville Boulevard interchange and must not be read as evidence that its construction is complete.

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