SR 78 Corridor Map

I-5/SR 78 Interchange Project

In the past few years, SANDAG and Caltrans have worked with stakeholders to complete a preliminary screening of project alternatives for the interchange. Improvements could include direct freeway-to-freeway connectors from southbound I-5 to eastbound SR 78 and westbound SR 78 to southbound I-5, direct access ramps to Express Lanes, and transit vehicle linkage.

Caltrans also is investigating the feasibility of interim operational improvements to improve the flow of traffic entering I-5 from SR 78.

Improvements to the I-5/SR 78 interchange are part of the SANDAG 2050 Regional Transportation Plan and are currently slated to begin construction between 2035-2040 pending funding availability. More information is available on the project page.

Woodland/Barham Interchange

The City of San Marcos and Caltrans are working together to redesign the existing East Barham Drive/Woodland Parkway interchange located in the City of San Marcos.  The project will reduce traffic congestion, increase roadway capacity, and improve safety. The project’s primary objective is to improve access to and from the freeway as well as to improve access for local vehicles, bicyclists, and pedestrians across the freeway.

This project includes interchange improvements that will widen or replace the East Barham Drive/Woodland Parkway undercrossing, widen and realign local streets in the immediate interchange area, widen and realign the westbound on- and off-ramps and eastbound off-ramp, relocate the eastbound on-ramp adjacent to the eastbound off-ramp, and signal upgrades the Rancheros Drive/westbound ramps, Woodland Parkway/eastbound ramps, Woodland Parkway/East Barham Drive, and the Woodland Parkway/Rancheros Drive intersections. Construction is anticipated to begin by 2025.

SR 78 Express Lanes Project

SANDAG and Caltrans have evaluated a proposal to construct two Managed Lanes, one in each direction, on SR 78 between I-5 and I-15. Other major improvements include bridge replacement/widening, ramp relocations, and street realignment operational improvements. The goal of the project is to improve the overall movement of people and goods between I-5 and I-15 on SR 78 by implementing the most cost-effective strategies while minimizing impacts to the surrounding communities. The environmental phase is partially funded, while design, and construction are currently unfunded.

SR 78 Asset Management

Improvements have been planned and are anticipated to be implemented in the near future along eastbound and westbound SR 78. Activities include pavement resurfacing, bridge rails, ADA ramps, culvert restoration, and a new westbound auxiliary lane between Nordahl and Twin Oaks Valley roads in San Marcos. Intelligent Transportation System technology improvements will help prepare for an automated future, improve traveler information, and reduce congestion and emissions.

In addition, Caltrans completed construction on eastbound and westbound auxiliary lanes between Twin Oaks Valley Road and East Barham Drive in 2018.