Frequently Asked Questions

General Questions

The Gap is an 18-mile stretch of I-25 from south of Castle Rock to Monument. It is the only four-lane section of I-25 between Denver and Colorado Springs, Colorado's two largest cities.

Over the years, congestion, crashes and delays have grown due to population growth and more people using the road. Following an exhaustive and aggressive study period, this project is fully funded and now under construction.

The project will:

  • widen 18 miles of I-25—from two to three lanes—from south of Castle Rock to Monument (The new lane in each direction will operate as an Express Lane to offer a reliable trip.);
  • widen shoulders;
  • reconstruct five bridges - at County Line Road, Plum Creek, Greenland Road, Spruce Mountain Road and Upper Lake Gulch Road;
  • build four new wildlife crossings;
  • add new overlay to the existing pavement;
  • modernize technology along the corridor; and
  • build a truck climbing lane on southbound I-25 from the Greenland area to Monument on a portion of the corridor.

Safety: Wider shoulders outside and inside the travel lanes will provide more room for vehicle pull-off and emergency response. This improvement will also help with drainage.

Driver choice: A new Express Lane in each direction of I-25 will give drivers a choice to use the general-purpose lanes for free or, when a shorter and more reliable trip time is needed, use the Express Lane in exchange for a toll. Carpoolers (vehicles with three or more people) and motorcyclists will be able to ride the Express Lane for free.

Trip reliability: Express Lanes provide short- and long-term trip reliability; the lanes are tolled to carry the right amount of traffic to ensure a reliable trip time. Travel times improve across the Express Lanes and general-purpose lanes.

Wildlife safety: Four new wildlife crossings and deer fencing will help prevent animals from darting into the road.

Improved pavement: A new overlay to the existing pavement will result in a smoother ride.

Improved infrastructure: Crews will reconstruct five bridges and extend ramps.

Improved truck access: A new truck climbing lane from the Greenland interchange south will provide better and safer access for trucks.

Advanced technology: Modernized communications and power along the corridor will enable advanced technology.

Construction began in early September 2018 and is scheduled for completion in November 2022.

The original project cost was $350 million. Additional funding was needed to cover the construction of the County Line Road bridge, southbound I-25 Monument Hill truck climbing lane, southbound I-25 truck chain-up station, and to address the issue of unsuitable soil found following the start of construction. In 2019 and 2020, funding became available for these improvements. The current total budget is $419 million. The project remained on budget, but the overall project cost increased when additional benefits were included.This project was funded through contributions from Douglas and El Paso counties, Pikes Peak Rural Transportation Authority and a federal INFRA grant.

No. CDOT will continue to operate and maintain the roadway. The High Performance Transportation Enterprise (HPTE) will set the toll rates based on keeping the right amount of vehicles in the Express Lanes so travel times are reliable.

Express Lanes & Tolling

Following environmental study, public involvement and evaluation of more than 100 alternatives for the I-25 corridor from C-470 to Monument, CDOT found the Express Lanes alternative best met the project's purpose and need to improve safety, mobility and travel reliability.

Adding an Express Lane can provide a level of travel reliability that a new general-purpose lane cannot; traffic on an Express Lane can be managed so vehicles are moving efficiently. Express Lanes on other highly traveled corridors in the state have proven to be successful in increasing roadway capacity, managing congestion, and providing travel choices, a reliable trip and improving travel times across all lanes.

To use any Colorado Express Lanes, you will need an ExpressToll account and pass to avoid a higher license plate toll. The Switchable HOV Transponder is the only pass that allows you to choose the carpool option and use the lanes for free if the driver has two or more passengers. Motorists can get a pass by visiting

Tolls on the I-25 South Gap project are expected to be the lowest in the state once Express Lanes are in operation, according to a traffic and revenue study released by Colorado's HTPE.

Based on the results and other data, the study found a rate of $0.15 per mile, or around $2.25 per trip (2017 dollars), would likely provide for a reliable travel option while improving travel times across the general-purpose lanes. This would be the lowest per-mile rate in Colorado.

The study will be used as a key source of information for the HPTE Board when it makes a final decision on toll rates a few months before the Express Lanes open to traffic in 2022. At that time, HPTE will conduct additional public outreach before setting toll rates.

Toll revenues will pay for the tolling equipment and installation, tolling operations and maintenance of the Express Lanes in the I-25 South Gap corridor to include snow plowing, debris removal and pavement repairs.

Travel Impacts

Throughout construction, drivers can expect narrower lanes and overnight lane closures. Please pay extra attention in construction zones.

Decreasing traffic impacts is a top priority for CDOT. During construction, two lanes of traffic will be maintained in each direction during daytime hours and peak travel times. Most lane and ramp closures will occur overnight, during off-peak times. Drivers will notice that lanes will be narrower and the interstate speed limit will be reduced to a maximum 60 mph (45 mph on the frontage roads).

During construction, motorists using the corridor will experience delays. Please check the latest information on road conditions before heading out. If necessary, allow some extra time to reach your destination.

A lack of good alternate routes is one of the reasons this project is a high priority for CDOT. During construction, drivers are asked to stay on I-25, and avoid using frontage roads or other routes to bypass construction.

To help decrease traffic impacts, we recommend using alternative commute options such as Bustang, vanpool or carpool.

The project team will maintain two lanes of traffic in each direction during the day. Lane restrictions that are necessary for safety reasons will occur at night. In addition, there will be no signed detours around the construction zone. It really is best for drivers to stay on I-25.

While there are no planned improvements to the frontage road along I-25 in this corridor, the I-25 South Gap project will, at times, impact local traffic on the frontage roads.

Part of the work along I-25 includes new drainage pipes. These same culverts run underneath frontage roads in some areas. To access the pipes under I-25, crews may need to close portions of the frontage roads. Those closures are expected periodically during the day and overnight. Local access will be maintained—flaggers will direct traffic during these intermittent closures.

Two lanes of traffic will remain open in both directions of I-25 during the day. Interstate lane closures will be limited to nights and off-peak travel times. A regular courtesy patrol and incident management team will help move impaired vehicles quickly.

The project team will coordinate with major events in the area and region, and work around-the-clock and on weekends (when needed) to deliver this project on time, on budget and with as few impacts as possible.

There are a variety of ways to stay in touch with the project. Sign up for text alerts by texting I25GAP to 21000. The project team will text when there is a planned or unplanned highway closure. Or, email us at [email protected] or call our hotline at 720-745-5434. Also, follow us on Facebook.