A full closure of the Airport Road median at the Diagonal Highway southwest of Longmont will occur on Monday, April 13 from 7 a.m. to 3 p.m.

Boulder County, Colo. - On Monday, April 13, work will begin at the Airport Road median at CO 119/Diagonal Highway southwest of Longmont to convert the median into a permanent, one-way northbound road. Southbound travel in the median will be permanently prohibited.

The Colorado Department of Transportation is implementing this change as part of the CO 119 Safety, Mobility and Bikeway Improvements Project to address significant safety concerns at the CO 119/Diagonal Highway intersection:

• Data shows that 85% of crashes involving southbound Airport Road and CO 119 result in injury, with most occurring when vehicles attempt to turn left onto northbound CO 119.
• Eliminating the southbound left turn onto northbound CO 119 (to Longmont) will reduce sideswipe and rear-end crashes, remove the need for a signal and bus queue jump lane at the current stop sign-controlled intersection, therefore improving overall corridor safety and mobility.

Map showing the Airport Road median at CO 119 intersection transitioning to northbound one-way travel.

Airport Road Full Median Closure on Monday, April 13

Work will begin with a single-day, full closure of the Airport Road median, between northbound and southbound CO 119/Diagonal Highway on Monday, April 13 from 7 a.m. to 3 p.m. as crews prepare the area for safety improvement work. The median will be closed to all modes of transportation.

During this closure, on April 13, both RTD bus stops at Airport Road and CO 119/Diagonal Highway (Stops #18005 and #19973) will be temporarily closed for pedestrian safety.

Detour Routes

• Eastbound travelers will turn right onto southbound CO 119, turn left onto 83rd Street, then turn left onto northbound CO 119.
• Westbound travelers will turn right onto northbound CO 119, turn left onto S Fordham Street, turn left onto southbound CO 119, then turn right to continue onto Airport Road.

Map showing the Airport Road median at CO 119 detour routes.

Phase 1 of Airport Road Safety Improvement Work

Immediately after the full median closure on Monday, April 13, the Airport Road and CO 119/Diagonal Highway intersection will transition to a one-way northbound road. This will also start the first phase of safety improvement work for the intersection, which will last approximately two months.

Phase 1 Traffic Impacts:

• Right lane and right turn lane closure on Airport Road just north of CO 119/Diagonal Highway.
• Northbound Airport Road median reduced to one lane. The two northbound left lanes on Airport Road, between northbound and southbound CO 119/Diagonal Highway, will be closed.
• Partial closure of the trail at Airport Road between northbound and southbound CO 119/Diagonal Highway.

Detours and Alternate Routes:

• When the Airport Road median becomes a northbound one-way road, travelers can use 83rd Street to access northbound CO 119/Diagonal Highway.
• Travelers turning right from southbound Airport Road onto southbound CO 119/Diagonal Highway can turn from the southbound lane.
• Pedestrians and cyclists will use the crosswalks on the east side of the intersection, travel southbound in the Airport Road median and turn left to connect with the trail in the median.
  • To provide this detour for pedestrians and cyclists, a lane will be closed in the Airport Road median, and a temporary trail surface will be added to connect to the trail between northbound and southbound CO 119/Diagonal Highway. Traffic barriers will protect the area in median from vehicles.

Map showing Phase 1 of Airport Road Safety Improvement work.

Remember: Slow For The Cone

The following tips are to help you stay safe while traveling through maintenance and construction work zones.

• Do not speed in work zones. Obey the posted speed limits.
• Stay Alert! Expect the unexpected.
• Watch for workers. Drive with caution.
• Don't change lanes unnecessarily.
• Colorado law prohibits holding or using a phone or other mobile device while driving, requiring all drivers to use a hands-free device.
• Turn on headlights so that workers and other drivers can see you.
• Be especially alert at night while driving in work zones.
• Expect delays, especially during peak travel times.
• Allow ample space between you and the car in front of you.
• Anticipate lane shifts and merge when directed to do so.
• Be patient!

Work schedules are subject to change and can vary based on conditions. Subscribe to CO 119 Diagonal Highway Safety, Mobility and Bikeway Project Construction Updates from CDOT.

View the CDOT CO 119 Safety, Mobility & Bikeway page for more construction updates.

Project Contacts

• CDOT phone: 720-378-8083
• CDOT email: co119safetyandmobility@gmail.com
• Boulder County phone: 303-441-4520
• Boulder County email: aphillips@bouldercounty.gov

Boulder County wants to ensure that everyone has equal access to our programs, activities, and services. To request an Americans with Disability Act (ADA) accommodation, please email ada@bouldercounty.gov, or call 303-441-1386. If you need help in another language, please email cppfrontdesk@bouldercounty.gov or call 303-441-3930.