I-5/SR 78 Interchange Improvement

Caltrans and SANDAG

Public Notice: Caltrans will hold a public scoping meeting on May 13, 2026, inviting the public to learn more about this project and share input. Comments can also be provided online between April 29 and May 29, 2026. 

SANDAG, Caltrans, and the Federal Highway Administration (FHWA) are teaming up to improve traffic flow where State Route 78 (SR 78) and Interstate 5 (I-5) meet. Cars in this area currently move through a signal at the I-5 southbound ramp/Vista Way intersection, causing traffic congestion, delays, and poor air quality. Travel demand is projected to increase in this area, placing further stress on the interchange.

The I-5/SR 78 Interchange Improvement project is intended to help meet anticipated travel demand and improve connectivity throughout the corridor. Caltrans is currently identifying project alternatives that could include improvements such as connecting and extending existing auxiliary lanes and reconfiguring the interchange to construct direct freeway-to-freeway connectors and/or ramps. Once alternatives have been identified, Caltrans will develop technical studies to evaluate the costs, impacts, and benefits of each alternative. 

For more information, check our News page for project updates, subscribe to our email list, or contact buildncc@sandag.org.

Project Timeline

Initial planning was federally funded.

This project is currently in the environmental phase. Caltrans is studying traffic patterns and identifying project alternatives which might include:

  • Adding direct freeway-to-freeway connectors from southbound I-5 to eastbound SR 78 and westbound SR 78 to southbound I-5
  • Building direct access ramps that connect to future carpool and transit vehicle lanes on I-5 and SR 78
  • Reconfiguring the existing interchange to accommodate the new connections outlined above

Once alternatives have been identified, Caltrans will develop technical studies to evaluate the costs, impacts, and benefits of each option.

The formal public input period is expected to begin in early 2025. The Environmental Impact Report/Environmental Impact Studies (EIR/EIS) is expected to be completed by 2029.

Federal funds of $8 million are available for preliminary design and environmental studies.

Pending funding, the project team plans to work on specific project designs from 2029 through 2032.
Pending funding, the project team plans to begin construction in 2033 and complete the project by 2037.

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