A 30-day grace period for drivers who weave in and out of express lanes on some Colorado highways is coming to an end.

Beginning Jan. 1, weaving drivers in express lanes in the Central 70, Interstate 25 South Gap and U.S. 36 corridors will be fined instead of receiving a warning, according to a news release Thursday from the Colorado Department of Transportation.

Drivers will be fined $75 if an infraction is paid within 20 days, $150 if paid later.

According to CDOT, entering and exiting the express lane outside of designated areas is “extremely dangerous.” Officials say it increases the risk of a crash because the speed significantly changes in the express lanes versus other highway lanes.

During the grace period from Dec. 1-17, the state of Colorado had issued 23,873 warnings to drivers weaving in and out of the express lanes.

The Safety and Tolling Enforcement Program was introduced last year on the I-70 Mountain Express Lane corridor, an eight-mile stretch that includes express lanes west of Denver. The Jan. 1 expansion includes I-70 between I-25 and Chambers Road in metro Denver, I-25 between Monument and Castle Rock, and U.S. 36 between Federal Boulevard and Table Mesa Drive between metro Denver and Boulder.

To learn more, visit CDOT’s website on express lanes.

The express lane changes come after the move Nov. 25 to dynamic tolling on two stretches of express lanes.

Toll rates change based on real-time traffic rather than time of day. The affected areas include an 18-mile stretch on the I-25 South Gap between Monument and Castle Rock. The other is on the westbound 12-mile stretch of Mountain Express Lanes between the Veterans Memorial Tunnel and Empire. 

“The South Gap and the Mountain Express Lanes are two of the most traveled corridors in the state and we want to do everything we can to help keep Express Lane speeds reliable,” said Piper Darlington, director of the Colorado Transportation Investment Office, the division of CDOT that owns and operates Colorado Express Lanes, in earlier Gazette reporting.

Drivers can see the current toll prices on overhead signs, which are adjusted every five to 15 minutes. The driver will pay the toll price displayed when they enter the express lane, whether or not it changes during their travel in that lane.