Motorists traveling along the 18mile stretch of Interstate 25 between Monument and Castle Rock started to pay Wednesday to use the new express lanes built on the northbound and southbound directions of the corridor.

Toll charges along the so-called I-25 South Gap went into effect at 6 a.m., Colorado Department of Transportation spokesman Tim Hoover said last week. From that day on, drivers in each direction will have the option to use the express lane in exchange for a toll or use the other two general purpose lanes for free.

The Colorado Transportation Investment Office recently approved the rates, using an adjustable pricing system so express lane users will pay different prices depending on the time of day.

“These are very basic time-of-day tolls tied to historic traffic levels at those times on those days. Higher the traffic, higher the toll. Lower the traffic, lower the toll,” Hoover told The Gazette in previous coverage.

The tolls will go live a little more than two years after the state transportation department opened the new express lanes in early December 2021 and implemented a testing period in 2022 and 2023, during which toll fees were temporarily waived.

For vehicles traveling both segments of the corridor — the first from Monument to Larkspur and the second from Larkspur to Castle Rock — trips will range from $1.50$9.46 each, depending on the time of day and whether the vehicle is registered under an Express Toll account, an all-electronic toll collection system available for Colorado’s express lanes as well as E-470 and

Northwest Parkway.

Motorcyclists and vehicles with three or more people can use the express lanes for free. Carpooling vehicles must have a driver plus at least two additional passengers, an Express Toll account and a switchable HOV transponder to use the express lanes for free, Hoover said.

Drivers can visit Expresstoll.com to create an account and/or purchase a switchable HOV transponder.

Trucks with four or more axles may also use the express lanes, but must pay a $25 surcharge on top of the tolls. The agency charges large trucks more because they’re slower-moving, put greater wear and tear on road infrastructure and can create visibility issues when traveling on the left side of the roadway, which can make it more difficult for other vehicles trying to pass, Hoover said.

Motorists who have an Express Toll account will save about 40% more when using the express lanes than motorists who don’t have an account, he said. Vehicles not registered with an Express Toll account pay the toll plus a surcharge to process the license plate.

The express lane rates for the I-25 South Gap are the lowest rate per mile in Colorado and are also among the lowest in the country, Hoover said.

Express Toll rates along the I-25 South Gap range between 70 cents to $2, depending on the time of day and which segment or segments of the corridor a vehicle travels.

That’s compared with, for example, express toll rates to use eastand westbound Central 70 between I-25 and Chambers Road in Aurora, which range from $1.50 to $4.50, depending on the time of day. Another example is the Express Toll rates on I-25 Central, from downtown Denver to U.S. 36, which range from $1.25 to $7.15, depending on the time of day.

Hoover said drivers using the I-25

South Gap express lanes can expect a time savings of between 20%-50%.

“If it was going to be a 40-minute trip, maybe it’s now just going to be a 30-minute trip or a 20-minute trip. It can make a huge difference,” he said.

Hoover reminded drivers that speed limits are no higher in the express lanes than in the general purpose lanes. Travelers should always adhere to posted speeds.

“Just because you’re going the speed limit doesn’t mean you’re not going faster than traffic in other lanes. The point of the express lanes is to give you a reliable trip time,” he said.

Hoover also reminded motorists the express lanes are not passing lanes and should not be used as such. Drivers can enter and exit the express lanes through the dashed lines only. Passing the solid white lines is illegal and dangerous due to the differences in speed between the express lanes and general purpose lanes, he said.

Drivers who cross the solid white lines into and out of the express lanes will receive a civil penalty and a $75 fine for the violation. The Colorado Department of Transportation has anti-weaving equipment to catch vehicles weaving in and out of the express lanes, Hoover said.

For more information on Colorado express lanes and how to use them, to see a map of Colorado’s express lanes and for more toll information, visit codot.gov/programs/expresslanes.