I-25 South Gap toll charges start Wednesday. Here’s what to know

I-25 stretches south from Denver. Feb. 19, 2022.
Kevin J. Beaty/Denverite
Cars drive on I-25, south of Denver. Feb. 19, 2022.

Drivers traveling along I-25 between southern Castle Rock and Monument must pay a toll to use the express lane starting Wednesday. 

The Colorado Department of Transportation completed construction on the $419 million I-25 South Gap project in November 2022. The new 18-mile stretch of highway is meant to increase safety and reduce traffic in an area where congestion, crashes and delays have become common. 

There is an express lane in each direction of the highway, and each direction consists of two zones, which charge different toll prices. Zone 1 is between Monument and Larkspur, and Zone 2 is between Larkspur and Castle Rock.  

Anyone can use the express lanes, but prices will vary depending on type of vehicle, how many passengers are being transported, and time of day.

For vehicles with just one or two passengers, prices will be cheaper if driving with an automatic vehicle identification system or ExpressToll transponder. Tolling based on reading license plates is more expensive due to higher administrative costs associated with verifying plates

Courtesy of CDOT

Vehicles that have a switchable high occupancy vehicle transponder for carpooling and motorcycles can use the express lanes for free, as can buses and other public transit vehicles. Semi-trunks with more than four axles have to pay a $25 surcharge regardless of the time and day.