When Caltrans and its community partners recently celebrated the opening of Interstate 15 through Mid-City San Diego, it spelled relief for those caught up in traffic congestion on other nearby freeways.

The opening of these new freeway lanes through the heart of City Heights was a historic day, both for the neighboring communities, which had waited more than three decades for the project, and the nation. This stretch of road was the last remaining piece of I-15 to be constructed as a freeway from where it starts in San Diego to where it ends at the U.S.-Canada border in Sweetgrass, Mont.

Commuters through City Heights no longer have to stop at the five traffic signals along the old route which followed 40th Street, saving precious time and fuel. When the remaining work is completed late this summer, the benefits will be even more significant.

Caltrans used computer-modeling software during the planning and design of I-15 to help estimate the regional benefit of the freeway. This modeling indicates that the new I-15 freeway will draw nearly 40,000 vehicles per day away from nearby I-805.

Forecasts show the benefits of this new freeway promise to keep building over the course of the next year, including:

• I-805 north of I-8 — 25,000 fewer vehicles per day.
• I-8 between I-805 and I-15 — 15,000 fewer vehicles.
• State Route 163 from I-805 to I-15 — 20,000 fewer vehicles.

During the next two decades, this new section of I-15 will carry more than 190,000 vehicles per day. Without this long-awaited regional transportation improvement, traffic congestion would have ruled other nearby routes. I-805 would have been particularly hard hit with a projected 315,000 vehicles per day by the year 2020.

The debut of this new portion of freeway already has changed travel patterns. Area motorists and traffic reporters have noticed that I-805 traffic congestion has been reduced. As drivers get used to the new freeway configuration — two lanes in each direction, ramps and connectors — they can expect this new freeway will have an even more noticeable impact on their lives.

The opening of I-15 through the Mid-City Area of San Diego is historic, but in some ways, from the local transportation perspective, history started the day this new section of freeway opened. The benefits should be visible on a number of levels — the nation benefits, the region benefits and the neighborhood benefits.

Caltrans District 11 Director Gary Gallegos heads a workforce of 1,500 state transportation employees in San Diego and Imperial counties. He is a registered civil engineer with more than 17 years of experience.