Overnight I-84 closures planned in Nampa, Caldwell starting Sunday night

Drivers on Interstate 84 in Canyon County should prepare for overnight closures and changing traffic patterns starting Sunday night, as the Idaho Transportation Department continues major improvement projects in Nampa and Caldwell.

Interstate 84 will close beneath the Karcher Road interchange in Nampa on Sunday and Monday nights to allow crews to work on the bridge.

Eastbound I-84 will be closed Sunday night into Monday morning and westbound I-84 will be closed Monday night into Tuesday morning. Both closures will run from 10 p.m. to 5 a.m., according to an ITD news release.

During the eastbound closure that starts Sunday night, drivers will exit at the Karcher interchange (Exit 33), cross Karcher Road and use the eastbound ramp to get back on I-84. During the westbound closure, drivers will exit at the Northside Interchange (Exit 35), travel north on Northside Boulevard, turn left on Karcher Road to head west and re-enter the highway at the westbound Karcher ramp.

The work is part of a broader project to add a third westbound lane on Karcher Road, aiming to improve traffic flow and safety, ITD said. Additional improvements include:

• A free-running right turn at the westbound off-ramp.

• Paving a third westbound lane from the off-ramp to Sundance Road.

• Reinforcing the Indian Creek Bridge.

• Updating signal equipment and adding a pedestrian flashing beacon.

• Building a mixed-use path on the north side of Karcher Road.

In Caldwell, ITD said it will implement a new traffic pattern on westbound I-84 starting Sunday night. Drivers are urged to use caution and watch for signs.

Westbound traffic will split into two lanes just past the 10th Avenue Interchange:

• The right lane will allow drivers to either continue west or exit at Centennial Way.

• The left lane will continue westbound with no access to Centennial Way.

A physical barrier will separate the lanes after the split, preventing lane changes. The lanes will merge together again just after the Centennial Way interchange.

To set up the new traffic pattern, the westbound off-ramp at Centennial Way will close from Sunday at 10 p.m. until Monday at 5 a.m. Drivers will be detoured to Exit 26.

In early August, westbound traffic should move back to the westbound side of the highway, and ITD said it expects to reopen the 10th Avenue westbound on-ramp, which closed in June for construction.

This work is part of the I-84 widening project in Caldwell, which began in November 2023. The project includes:

• Widening I-84 to three lanes in each direction, with auxiliary lanes between interchanges.

• Replacing the 10th Avenue interchange.

• Removing one westbound on-ramp at 10th Avenue.

• Updating the pedestrian overpass.

• Building a sound wall along Hannibal Street.

• Adding a traffic signal at the Centennial Way westbound ramps.

The speed limit in the construction zone is 55 mph. Construction in Caldwell is not scheduled for completion until 2027.

This story was originally published July 11, 2025 at 12:51 PM.