Looking ahead 20 years, Caltrans began work on the State Route 46 Corridor System Management Plan in 2005. This roadway, SR-46, is a critical east-west corridor in the state, connecting Highway 1 on the Central Coast to Highway 101 through San Luis Obispo County onto Interstate 5 in Kern County and State Route 99 in the San Joaquin Valley.

Atkinson Construction’s staging work seen underway for the form and soffit pour on the SR-41/SR-46 separation bridge.

State Route 46 is a designated Focus Route in the State’s Interregional Transportation Strategic Plan. It primarily serves interregional and interstate traffic, and, of course, is also used by the residents of Paso Robles, Cholame, Shandon, and Whitley Gardens.

With concrete mixer trucks in place, side-by-side, the stem and soffit pour on the SR-41/SR-46 separation bridge begins.

As one of the few east-west routes connecting Interstate 5 to U.S. Highway 101, two-lane SR-46 was experiencing increasing peak-hour congestion, according to the State Route 46 Corridor System Management Plan published in June 2009. And according to data collected in 2017, 17% of the traffic volume were trucks, with 60% of those trucks being five-axle and larger. By this determination, State Route 46 is an Essential Freight Corridor.

Atkinson completed the 900-cubic-yard pour in just under 15 hours.

Safety became a prime concern as well, with limited passing opportunities on the two-lane roadway. The risk of collision was heightened as drivers attempt to pass slower vehicles, often longer-length semi-trucks and trailers. The Corridor Project then defined its purpose as to minimize fatal accidents, improve safety, and reduce existing and future peak-hour congestion on State Route 46, especially between Paso Robles and Cholame.

Of note, Cholame is the site of James Dean Memorial Junction, an historical landmark on SR-46 dedicated to the memory of the actor who starred in Rebel Without a Cause, East of Eden, and Giant. On September 30, 1955, Dean fatally crashed his Porsche 550 at the junction of SR-46 and SR-41.

Current work approved in the State Route 46 Corridor System Management Plan includes the State Route 46 Corridor Improvement Project, initiated by the San Luis Obispo Council of Governments to enhance operations on SR-46 between Airport Road at Postmile (PM) 32.2 in the City of Paso Robles to the east junction SR-41 and SR-46 at PM 57.8.

Divided into three sections, the Cholame Section is budgeted at $124,500,000 for construction and support costs, Wye Section at $146,200,000, and Antelope Grade Section at $134,696,000. Funding is provided by a combination of local, state, and federal dollars. Completed to date are the Union and three Witley Sections, which were funded through SB 1.

The Cholame Section extends from PM 49.7 to PM 54.7, with construction started in March 2022. The Wye Section goes from PM 54.0 to PM 57.8 and construction began in May 2023.

The Antelope Grade Section covers PM 57.3 to across the county line to PM 0.4 in Kern County.

Guy F. Atkinson Construction at Work Under a CM/GC Contract

Under a Construction Manager/General Contractor (CM/GC) contract, Guy F. Atkinson Construction is converting the existing two-lane SR-46 to a four-lane divided expressway in the Cholame, Wye, and Antelope Grade Sections, covering 13 miles.

A nighttime shot of Atkinson’s stem and soffit pour on the SR-41/SR-46 separation bridge.

The project scope includes 48 lane miles of pavement rehabilitation, including Continuously Reinforced Concrete Pavement (CRCP), a trumpet-style interchange at SR-46/SR-41, seven bridges, 5.5 million cubic yards of earthwork, two CHP inspection stations, drainage and roadway work, third-party utility coordination, and environmental permitting support. Atkinson’s CMGC contract value is $268 million.

The Cholame Section includes 151,900 cubic yards (CY) of base, 61,600 tons of HMA, and 75,000 CY of CRCP. The Wye Section is being constructed with 159,700 CY of base, 79,900 tons of HMA, and 18,400 CY of Lean Concrete Base (LCB).

To repurpose existing onsite materials, as well as to hold down costs, the existing SR-46 roadway pavement is being recycled using a mobile crusher and a pulverizer to create the base section in the new alignment.

Targeted completion for the Cholame segment is early 2025, and for the Wye segment, early 2026. After a short pause following the completion of the Wye Section, work will begin on the third and final segment in the corridor, the Antelope Grade Section.

Big thanks and a tip of the hard hat to Atkinson Project Manager Mike Ashby for his help and contributions to this story.