I-5 / SR-78 Interchange Project
I-5 / SR-78 Interchange Project
The I-5/SR-78 interchange is currently controlled by traffic signals and no longer handles today’s traffic demand. Heavy westbound SR-78 traffic trying to access southbound I-5 often exceeds the intersection capacity, causing backups that extend onto SR-78. This congestion also leads some drivers to divert onto local streets, increasing traffic in nearby communities. Additionally, the short distance between this freeway-to-freeway interchange leads drivers to complete quick lane changes, creating weaving that slows traffic and reduces safety on both I-5 and SR-78.
I-5 / SR-78 Interchange Project: PA&ED Phase
In preparation for the environmental document, Caltrans is [insert what you are doing in this phase and what engagement you are seeking].
Project Description:
The purpose of the Interstate 5/State Route 78 (I-5/SR-78) Interchange Improvement Project is to improve safety and traffic flow at the interchange. The project will focus on addressing the heavily traveled westbound SR-78 to southbound I-5 connection, as well as improving access to local communities, coastal resources and recreational destinations. These improvements aim to reduce congestion on SR-78, limit cut-through traffic on local streets, and improve travel conditions for residents, visitors, and regional commuters.
The project objectives are:
- Safety and Traffic Operations: Reduce or eliminate conflicts at the I-5/SR-78 interchange to enhance safety and operations. Improvements will reduce conflicting movements and provide direct connectors for general-purpose lanes or managed lanes, as deemed necessary and feasible.
- Improve Traffic Flow Between Closely Spaced Interchanges: Minimize conflict points caused by the proximity of interchanges. This will help reduce weaving, support smoother merging and diverging movements, and may include access modifications, advanced signage, and auxiliary lanes.
- Design standards: Improve interchange design to meet current Caltrans standards.
- Encourage Sustainable Transportation: Incorporate features that promote carpooling, vanpooling, transit, pedestrian, and bicyclist contributing to reduced congestion and environmental benefits, specifically contributing to lower emissions.
- Natural Resources and Community Livability: Strive to demonstrate a balanced approach that considers responsible stewardship of natural resources in relation to the project scope, while supporting community livability within the project area.
Project Schedule:
- Preliminary Planning: 2012-2021
- Environmental: 2024-2029
- Public review that will inform the Environmental Impact Report/Environmental Impact Studies (EIR/EIS) scheduled for spring of 2025.
- Environmental Impact Report/Environmental Impact Studies (EIR/EIS) expected to be complete by 2029.
- Design 2029-2034
- Construction 2034-2038 (pending funding)
Map: 
Funding and Cost:
The proposed I-5/SR-78 Interchange Project is federally funded for the initial planning and environmental efforts. $8 million is available for Preliminary Design and Environmental Studies for 2024-2029. Over the next few years as project alternatives are refined, additional funding will need to be identified for Design and Construction.