OCEANSIDE — Big changes are finally in motion for the much-beleaguered Interstate 5/State Route 78 interchange and corridor.
For decades, motorists and residents have clamored for a new interchange, but now, Caltrans has reached new heights and is moving forward with serious proposals to modernize and redesign the freeway interchange. Caltrans, along with the San Diego Association of Governments, is hosting a public meeting on Wednesday from 6-7:30 p.m. at South Oceanside Elementary School, 1806 S. Home St.
The milestone for Caltrans is kicking off the environmental study and scoping phases of the project. On Wednesday, the agency will introduce the project to the public, and there will be many stations with more details on the timeline, project alternatives, environmental factors, cost, and staff to answer questions, according to Tracey Roberts, Caltrans District 11 deputy district director-Environmental.
She and Caltrans Public Affairs Manager Stephen Welborn both emphasized the need for the public to comment at the meeting or online. The deadline to submit comments is May 29, although both stressed no decision has been made about the possible design alternatives, which is why public comment is being solicited. (Comment webpage here)
Although Caltrans has studied improvements at the I‑5/State Route 78 interchange for years, the current effort marks the formal start of the environmental review and public scoping process, not approval of a final design or a guarantee of construction. Agency officials stressed that the purpose of the meeting and comment period is to gather input early, before any alternative is selected or advanced, and to identify potential environmental and community impacts that must be studied under state law.
“This is a long-time coming project,” Roberts explained. “There has been quite a bit of evolution, and it is one of the pieces of the puzzle to the North County corridor. We can look at how traffic demand exceeds this interchange, and we can redesign to find a solution.”
The problematic interchange is famous for its stop signal on the west end of the SR 78 exit ramp turning into Vista Way in South Oceanside. Motorists must also wait at the stoplight to enter I-5 on the southbound on-ramp. Merging north onto I-5 is straightforward, but the stoplight backs up traffic as cars sit idling as traffic cycles through the light.
What was once a more practical traffic management system is now overwhelmed as North County’s population has grown significantly over the past 40 years, Roberts said. Additionally, the congestion pushes traffic onto neighboring streets, and close ramp spacing forces rapid lane changes, especially for those drivers unfamiliar with the interchange’s layout and stoplight.
As such, Roberts said a primary goal is to improve traffic flow and safety, consider direct connectors (HOV or managed lanes) as the project enters the environmental and scoping stages. Caltrans released its Notice of Preparation last week.
The project’s cost, though, has yet to be determined, although Caltrans has up to $12 million for preliminary design and environmental studies. Another $50 million is available for the design phase from 2029-34, according to Caltrans’ website.
“We’ve been thinking about this interchange and working on it for over 10 years,” Welborn added. “We’ve gone through similar stages and talked about alternatives to the community in the past. We’ve never really made it this far because the alternates just weren’t there, and we didn’t get the community buy-in.”
Caltrans has three design alternatives listed on its website, but Roberts said those can change as they gather more information and learn more from residents and frequent users of the interchange. The current alternatives also include a “no-build” option as required by state law.
Regardless, the preliminary alternatives are as follows:
Alternative 1 — The potential solution 1 will remove the signalized intersection along Vista Way for drivers using the left-hand turn movement for westbound SR-78 to southbound I-5. This proposal will also remove access for drivers on eastbound Vista Way and eastbound Vista Way to the northbound I-5 loop on-ramp. The traffic on eastbound Vista Way will be redirected to Cassidy and other local streets.
Alternative 2 — This would incorporate a managed lane connection for drivers traveling from I-5 northbound to SR-78, and from SR-78 westbound to I-5 southbound. This would remove the I-5 southbound to westbound SR-78 turning movement as well as the eastbound Vista Way to northbound I-5 loop on-ramp.
Alternative 3 — This would provide a general-purpose connection from westbound SR-78 to southbound I-5 and would remove the eastbound Vista Way to northbound I-5 loop on-ramp.
“This is the kick-off for the environmental analysis phase,” Roberts said. “The most important part of that is what we’re doing right now, the scoping phase. We will discuss the various environmental constraints and subsequent studies that we need to do to determine levels of impact for positive and on the negative side, so that can help us determine our next steps. It’s collecting actual information from the public.”
As for the timeline, Caltrans is in the environmental study phase, which Roberts said will be completed in 2029. The draft environmental impact report (EIR) is expected to be released in January 2029, which will be open for more public comments, followed by the final EIR in October 2029.
From 2029-2034, the project will enter the design phase with an expected construction timeline from 2034-38, depending on funding, according to Roberts and Welborn.
The interchange presents a unique challenge with a stoplight connecting two major highways, a rare sight in freeway design. Roberts said it’s important for Caltrans to identify holistic solutions to benefit the entire region and to look at how the interchange wasn’t designed to handle the current level of traffic.
She said standards have changed over the decades, and with the I-5/78 interchange, drivers have less time to respond when entering the interchange, traffic onto local streets and more. Roberts said once all, or as many issues are identified, then Caltrans can start more robust planning and design.
This is where the public comes in, she said. Residents and frequent users have a more thorough and intimate knowledge of the interchange, traffic flows and other patterns Caltrans may not have identified. So, the feedback from residents is critical, Roberts said.
As for the environmental phase, she said the process is long and thorough, as state law requires a list of studies. Roberts said Caltrans will study air quality, traffic, vehicle miles traveled, impacts on the community and Buena Vista Lagoon, plus other biological issues, cultural resources and paleontology.
“Anything with an ology, we’ll be looking at,” she explained. “There’s quite a bit of I’s we dot and t’s we must cross in order to ensure that we’re meeting the state’s requirements. That’s a taste of it. During the scoping meeting, we actually lay out all of the studies we’re going to do and why we’re doing them.”
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