Caltrans planners and engineers are working with Skanska USA Civil West California to upgrade and repair State Route 78, one of the most used east-west roads in San Diego County.
Caltrans and Skanska photo
The job is 40 percent complete, with a scheduled finish date of 2027. The rehabilitation work for S.R. 78 begins at Interstate 5 in Oceanside to Broadway and Lincoln Parkway in Escondido, extending 17.7 mi. to the west. The route is used heavily by commuters and by people accessing the major north-south interstates to reach Orange and Riverside counties.
Construction Equipment Guide spoke with the Caltrans team of Wameedh Tozy, North County corridor project manager, and Yong Pak, North Country corridor construction engineer and senior resident engineer, about the $135 million project.
"Maintaining the highway is a top priority to ensure steady and reliable traffic flow," Pak said.
The highway meanders through San Diego County, connecting the coastal cities with inland and desert communities.
"Some truck lanes required a dig out of asphalt, replacement and reinforcement with as much as five inches of additional asphalt," Pak said. "The truck traffic required the asphalt to be reinforced because of the heavy loads."
The project required 130,000 tons of asphalt and an additional 3,000 cu. yds. of concrete for improvements to ADA ramps, bridge widening, drainage, signals, lighting and sign structures.
Caltrans and Skanska photo
A project like this, covering nearly 20 mi., offered Caltrans many opportunities for recycling. Workers crushed concrete that will be used in the project's new auxiliary lanes as well as other projects in the county. Contractor RJ Noble used asphalt millings to produce recycled asphalt pavement (RAP) for use in other road projects.
The paving team rehabilitated many surfaces through cold planing and milling deteriorated sections. The team worked not just on main roads but also built smoother shoulders and freeway ramps. In some cases, the construction team adjusted the ramps to allow for a smoother traffic flow.
Mar Vista Bridge
In addition to paving, the workers took on restructuring the Mar Vista Bridge. Through careful planning, the team was able to complete the bridge work in just five weekend closures, instead of the 10 that were planned. This construction management saved motorists headaches and saved the construction team time and money.
The team emphasized working with different municipalities and railway entities affected by the construction.
"Both Caltrans and Skanska implemented a proactive coordination with the adjacent communities," Tozy said. "We held quarterly meetings and provided project updates. We also regularly inform communities of lane closures and other work that impacted the communities."
Caltrans and Skanska photo
Caltrans and contractors believe that the project will make a difference to motorists. They believe the road work will improve ride quality and safety by reducing bumpiness, while reducing the need for costlier repairs over the next 10-15 years.
In addition, workers will add an acceleration lane to relieve congestion on eastbound S.R. 78. The team believes that the new paving will aid future improvements by decreasing flat tires and accidents. The team is upgrading striping and signage in many areas as well as improving visibility.
The Caltrans and Skanska partnership made efforts to improve safety for workers and residents.
ADA curb ramp construction was staged to allow safer pedestrian access during construction. The team also used attenuators and required a 6-ft. buffer zone when working at night under lane closures. Attenuators, mounted on trailers or on trucks, can absorb impact from careless drivers while keeping workers and other motorists safe.
Caltrans worked closely with the California Highway Patrol to provide protection during nighttime lane and freeway closures. The Caltrans team also used technology called Mooven, an AI-powered platform that uses data to pinpoint the best time for work, reducing exposure to work zones for both workers and motorists.
Caltrans and Skanska photo
Some truck lanes required a dig out of asphalt, replacement and reinforcement with as much as 5 in. inches of asphalt.
The work team used micro trenching techniques to handle the fiber optic utilities.
"We used micro trenching and directional boring to install the lines beneath the highway and bring the fiber optic utilities in their proper locations," Pak said. "We could do this and not interrupt either construction or the current traffic pattern."
For the project, the construction team used a normal fleet of equipment, including bulldozers, articulated trucks, excavators, front-end loaders, an asphalt paver and asphalt rollers. The team brought in specialized equipment for the work on the Mar Vista bridge, including an excavator with a 15-ft. catch bucket attachment to prevent debris from falling on the roadway.
The electrical subcontractor used a Vermeer RTX1250 micro trencher to trench and install the new fiber optic (approximately 2.5-in. wide trench), Ditch Witch R300, Ditch Witch Vacuum trucks and 1CM concrete buggy for slurry placement in the micro trench. CEG
(Photos courtesy of Caltrans and Skanska.
