St. Vrain Greenway - Phase 13 - Eastern Extension - City of Longmont

St. Vrain Greenway – Phase 13 – Eastern Extension

A dirt road appears to the right of some dry-looking vegetation. The rocky mountains and a bright blue sky appear in the background.

Phase 13 will extend the St. Vrain Greenway Trail more than two miles northeast from the Sandstone Ranch Nature Area to the trail network at St. Vrain State Park. This link will eventually connect to the Weld Legacy Trail east of I-25 in the Town of Firestone. The St. Vrain Greenway is also part of the statewide Colorado Front Range Trail, which is planned to run from Wyoming to New Mexico.

 

The work includes two pedestrian bridges—one north of Colorado Highway 119 over St. Vrain Creek and another south of the highway overlooking St. Vrain Creek. A concrete underpass will also be built beneath the highway to help pedestrians and bicyclists cross safely.

 

Other improvements include adding erosion control measures to help prevent soil from washing away, installing new fencing to guide trail users and protect nearby areas, and landscaping to revegetate areas impacted during construction.

 

The project is partially funded by the Denver Regional Council of Governments (DRCOG) Multimodal Options Funds Transportation Improvement Program (MMOF TIP) grant, which is administered by the Colorado Department of Transportation (CDOT).

 

The City adopted the St. Vrain Greenway Master Plan – East Corridor Update in 2001. The plan was developed with consultants, key stakeholders, and residents. It identified a trail route along the St. Vrain Creek corridor between Main Street and where St. Vrain Creek meets Boulder Creek.

 

Map of the St. Vrain Greenway from Sandstone Ranch Community Park and Nature area to St. Vrain St. Park.

 

Project Updates

 

July 30, 2026

  • Crews will complete overnight work Sunday, Aug. 9, and Monday, Aug. 10, from 6 pm to 7 am to shift traffic into Phase 2 of construction for the St. Vrain Greenway Phase 13 pedestrian underpass.
  • Overnight work will occur on Colorado Highway 119 between County Road 5 and County Road 7.
  • Sunday night, Aug. 9, crews will stripe the roadway, shift westbound traffic and install concrete barriers.
  • Monday night, Aug. 10, crews will shift eastbound traffic. The new traffic pattern will be in place by 7 am Tuesday, Aug. 11. Westbound traffic will shift to the outside shoulder, and eastbound traffic will use temporary lanes in the center of the roadway. Two lanes will remain open in each direction with concrete barriers separating opposing traffic.
  • The Phase 2 traffic pattern will remain in place through the winter while crews construct the pedestrian underpass. The speed limit through the work zone will remain 45 mph.

 

Please slow down, follow posted signs and watch for workers when traveling through the work zone.

 

July 7, 2026

This month’s construction activities:

  • Continue trail construction
  • Advance construction of Bridge 1 and its foundations
  • Build the noise barrier wall
  • Continue work on the trail underpass
  • Relocate utilities
  • Install tensile wire and the privacy fence
  • Perform dewatering operations
  • Pave the back of westbound CO 119
  • Complete asphalt paving for the detour
  • Implement the Phase 2 traffic switch (if conditions allow)

 

April 3, 2026

Trail Construction along Sandstone Ranch Nature Area:

  • Placement of crusher fines is underway
  • Retaining wall work continues
  • Pedestrian ramps are in construction, with concrete paving scheduled as the next step

 

Bridge & Underpass Construction:

  • Work is underway with crews preparing the site
  • Activities include excavation for culvert placement and other foundational work

 

March 18, 2026

  • Overnight work is scheduled to set up the Phase 1 traffic pattern.
  • Sunday, March 22: Crews will stripe the road, shift eastbound lanes and place concrete barrier
  • Monday, March 23: Westbound lanes will be shifted and traffic signal head work will be completed

 

March 17, 2026

  • Construction of the pedestrian underpass beneath CO 119 begins.
  • Starting Monday, March 23, a new traffic alignment will be in place on CO 119, located west of the St. Vrain Creek Bridge.
  • The new traffic pattern will move eastbound traffic to the right shoulder and route westbound traffic through temporary center lanes to accommodate construction in the westbound lanes.
  • Two lanes of traffic will remain open in each direction.
  • This new traffic configuration will continue through late August.
  • Drivers should follow posted signs through the construction zone.
  • The speed limit will be reduced to 45 MPH through the work zone.

 

March 11, 2026

Access to the dirt trail connecting the upper Sandstone Ranch Parking Area near the Visitor Center and Sandstone Drive will be closed through late April due to electrical work and concrete trail construction in the area.

 

February 23, 2026

Contractors experienced excavating issues on 2/21. This delayed the concrete pour until 2/24, extending the Sandstone Drive closure to Friday, Feb. 27.

 

February 19, 2026

  • Beginning Wednesday, Feb. 25, shoulder and median closures will be in place on Highway 119 as crews start clearing and grubbing in preparation for construction.
  • The Sandstone Drive closure will be extended until Thursday, Feb. 26.

 

February 6, 2026

Sandstone Drive will be closed for reconstruction between the turn off to the Sandstone Ranch Parking Area and the Visitors Center from Saturday, Feb. 21, through Wednesday, Feb. 25. The closure is necessary to allow new concrete to properly cure.

 

During this time, visitors should use the Sandstone Ranch Parking Area or parking lots at the soccer fields. The park and St. Vrain Greenway will remain accessible from those locations. Please follow posted signage for trail access.

 

January 23, 2026

Beginning Monday, January 26, access to the dirt trail from the Sandstone Ranch Parking Area near the Visitors Center to Sandstone Drive will be intermittently closed during active work to allow equipment access and ensure user safety.

 

December 19, 2026

  • Beginning Tuesday, December 23, a portion of the Sandstone Ranch Parking Area near the Visitors Center will be closed for the duration of the project.
  • Access to the trails and the Visitors Center will remain open.
  • Additional parking is available at the Visitors Center and the Sandstone Soccer Complex.

 

Schedule

  • Public Process – Completed, 2001 (as part of the St. Vrain Greenway Master Plan)
  • Design Bid – Completed, summer 2021
  • Design – Completed, February 2025
  • Construction Bid – Completed, September 2025
  • Construction – January 2026 to spring 2027

 

Frequently Asked Questions

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