US 36 Bridges at St. Vrain and Left Hand Creek

Expect traffic closures, stops and delays starting around 9 a.m. Wednesday, Jan. 17 as crews set girders for the new bridge over Left Hand Creek.

  • Expect about eight, 20-minute closures of US 36 for girder placement.
  • If work continues past 4 p.m. and causes notable traffic back-ups, crews will suspend further work until after 6 p.m.


  • US 36 via Neva/Niwot Road to 63rd, back down to US 36 via Nelson Road
  • CO 66 east to Hover Road, south to CO 119 toward Boulder
  • South on US 36 to Nelson Road, east to Airport Road, and south to CO 119 toward Boulder
  • From Boulder to Lyons: Jay Road east to CO 119, north to Hover Road, north to CO 66, and west to Lyons

Project Facts

  • Budget: $10 million to $20 million

Project Team

  • Contractor: American Civil Constructors

Upcoming Work

The project team plans to have limited traffic disruptions throughou December. Work and traffic impacts will include:

  • For one day, crews will reduce traffic to one lane in each direction of US 36 as they stripe the crosswalk at McConnell Drive.
  • Crews will construct abutments and the superstructure at the Left Hand Creek Bridge.
  • The team will perform bank stabilization and protection in the St. Vrain just east of Lyons.
  • Crews will install storm drainage at US 36 and CO 7.
    This work is tentative.

Crews will be setting the 153-foot girders for the Left Hand Creek bridge. Expect traffic holds up to 20 minutes while the girders are being set. An alternate route is advised.

Advanced warning signs on both ends of the project will notify the traveling public on what date the girders will be set.


Crews will replace the 62-year-old culvert at US 36 and Left Hand Creek with a wider bridge that spans the creek—allowing a 100-year flood event to pass under the highway. They also will restore Left Hand Creek to a natural, resilient state, in coordination with other restoration efforts east and west of US 36.

Bridge features will include:

  • 6- to 8-foot shoulders;
  • two, 12-foot travel lanes;
  • a northbound left-turn lane to Middle Fork Drive; and
  • a southbound right-turn/deceleration lane to Middle Fork Drive.

In the Town of Lyons, work includes protection efforts against scour—or erosion—on three bridges, and minor drainage improvements.

Traffic Impacts

  • Normal work hours: 8:30 a.m. – 3:30 p.m. Monday through Friday
  • Traffic will be reduced to one lane during paving.
  • A 25 mph speed limit will be strictly enforced within the mile-long workzone during this two-week window.

Damage Overview

This section of US 36 is one of the main corridors providing access between Estes Park and Boulder crossing both the St. Vrain Creek and Left Hand Creek. Floodwaters caused extensive damage to these channels as well as the structures along US 36. Damage included large amounts of debris an sediment deposit, erosion of the roadway embankment, overtopping of the roadway, scour damage of the bridge piers and abutments, and exposing underground utilities. 



One of the goals in the repair process is to introduce certain betterments to roadway facilities that were damaged and make them more resilient to similar storm events in the future. Having analyzed the damage caused during the flood event, certain design elements will be incorporated in an effort to prevent or lessen the severe damage that significant flood events can cause. The permanent repair phase will allow for the betterment of drainage facilities and erosion protection areas throughout the corridor that can handle the high flows from large storm events and protect facilities from potential damage in the future.

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