Three new auxiliary lanes on Interstate 15 have been open to Temecula drivers since late July, and Caltrans' $33.8 million improvement project is entering its final stretch.

The city announced Wednesday, Oct. 28, that the lanes are open and final sign and electrical work is underway, Patch reported.

The three new lanes connect key interchanges along the I-15 corridor through Temecula:

  • Northbound I-15 from Rancho California Road to Winchester Road
  • Southbound I-15 from Winchester Road to Rancho California Road
  • Southbound I-15 from Rancho California Road to Temecula Parkway

The lanes are designed to give drivers more room to merge between interchanges, improving traffic flow along the corridor.

What's left

The project is not quite done. According to the Caltrans project page, contractor crews have removed concrete k-rail barriers and replaced them with barrels to mark closed areas. Permanent striping was completed in September.

Remaining electrical loop installation will require additional night work at lanes and ramps, as needed, through fall 2026, Caltrans said. Night shifts run from 9 p.m. to 7 a.m. and include overhead sign installation. Drivers should expect nighttime lane closures in the northbound direction, with at least one lane open each way.

Daytime punch-list work continues Monday through Friday, 6 a.m. to 2:30 p.m., behind safety barriers. That work requires no lane or ramp closures, according to Caltrans.

Broader project scope

Beyond the auxiliary lanes, the California Department of Transportation (Caltrans) project includes widening shoulders at Empire Creek Bridge, expanding the Rancho California Road on-ramps, and installing a sound wall and guardrails.

The lanes began opening in late July 2026, according to Patch's earlier reporting. The overall project had been expected to wrap up by August 2026, but finish work has extended into fall.

Why it matters for commuters

The I-15 corridor through Temecula is one of the region's worst bottlenecks. Northbound between Winchester Road and the I-15/I-215 junction, high vehicle volumes cause backups stretching 3 to 12 miles every weekday and many weekends, according to the City of Temecula, as Top of Temecula reported.

The auxiliary lanes address the segment between Temecula Parkway and Winchester Road. A separate city interchange project covering Winchester Road to the I-215 junction has a completion target of March 2029.