A semi-truck fire has shut down the three rightmost lanes of northbound Interstate 805 at Main Street in Chula Vista, along with the Main Street onramp, as crews work to put out flames and clear debris from the roadway. Caltrans District 11 first reported the closure Wednesday afternoon, warning commuters that the right lanes were blocked due to the fire.
What's Closed and for How Long
According to Caltrans District 11
, lanes 3, 4 and 5 of northbound I-805 at Main Street were shut down because of the semi fire, with the Main Street onramp also remaining closed. The closure followed an earlier update in which only the right two lanes had been blocked, before the shutdown expanded to cover three lanes. The California Highway Patrol's San Diego division has estimated the closure will last roughly five hours, according to
CHP San Diego
.
The closure affects lanes 3, 4 and 5 of northbound I-805.
Truck Lane Rules
California law requires heavy commercial trucks and vehicles towing trailers to travel exclusively in the far-right lanes on freeways with four or more lanes in one direction, a rule detailed by AARoads.
The Main Street interchange is north of State Route 905, which connects directly to the Otay Mesa Port of Entry, San Diego County's primary land border crossing for commercial freight, according to the California Transportation Commission.
A Vital Bypass for South Bay Commuters
I-805 functions as an inland bypass for Interstate 5, running from the San Ysidro border region through Chula Vista and National City, per Wikipedia. The freeway's role as a bypass makes any multi-lane shutdown a significant disruption for South Bay drivers trying to get home or make deliveries.
With the Main Street onramp closed, nearby surface streets may absorb displaced traffic, as prolonged freeway ramp shutdowns can push congestion onto local arterials.
Wednesday's fire is the latest in a string of serious incidents on I-805 this month. Hoodline's earlier coverage detailed a fatal crash that shut down southbound lanes in National City during morning rush, and noted that San Diego County recorded 13,790 traffic collisions resulting in injuries or fatalities in 2025. A prior semi-truck collision near Mission Valley once triggered a 12-hour closure of southbound I-805 lanes, illustrating how severe truck incidents on this corridor can ripple across the region for hours.
Caltrans District 11 has not yet announced a specific time for when all lanes and the Main Street onramp will reopen. The cause of the fire, whether any hazardous cargo was involved, and whether anyone was injured remain unknown as cleanup continues.
