CDOT Rockfall Work on SH 3 Progressing Very Well in First Week

August 27, 2014 - Southwestern Colorado/CDOT Region 5 - Full closures of south end maintain safety, speed project completion by entire season.

DURANGO, CO – After just five working days, crews working on the Colorado Department of Transportation’s State Highway (SH) 3 rockfall mitigation project have made great progress.

“We are halfway done with our rock removal already, and we had estimated this to take 13 days,” said Tom Allen, project engineer from Yeh & Associates. “Progress over the next week or so may slow down a bit as we work with different kinds of rock; the shale, for example, does not come down in large slabs like the sandstone does. Regardless, I’m pleased with the results so far.”

The approximately .7-mile project work zone lies between the junction with US 160/550 and Sawmill Road (south). This project will reduce the risk of rockfall in this area, as well as provide measures to capture some material in the event of rockfall. The work is anticipated to be complete in mid-November 2014, with a possibility for some minor continued work in spring 2015. The full project—contracted to TK Construction for $1.56* million—also includes rockfall mitigation (to begin in early 2015) on SH 145 just south of Telluride.

Project Details: In the past 10 years, there have been five accidents involving rocks coming down in this .7-mile section—two of which involved injuries. The safety improvements described below will reduce the risk of rockfall for the average 8,790 vehicles driving along SH 3 each day. Here are some project specifics:

  • Crews will remove about 30-40 tons of material (predominately shale and sandstone) per day, which will equate to some 500-1,000 tons—or 500-1,000 cubic yard—of material removed by project completion.

  • Rock removal (or scaling) will be done with the use of some/all of the following: pry bars, small explosive devices, expansive grout or airbags inserted and inflated behind rocks.

  • Rock debris will be hauled away to a local gravel pit.

  • Drilling with the use of a crane in the roadway will take place; the drilled holes will make way for steel posts to anchor the rockfall netting.

  • Steel posts 6 to 12 feet long will be anchored into the drilled holes; these posts will have varying angles to accommodate the rockfall cable netting that will hang from them.

  • The cable netting—8-inch squares of ½-inch steel—will hang from the posts to form a 1,600-foot wide by 30-foot-long “curtain;” the curtain will hang away from the hillside at the top, rather than being anchored down against the rock face—this way, it is positioned to catch rocks that fall from above.

  • 34-inch tall concrete barrier will be reinstalled in the culvert at the base of the hillside.

Purpose of a full road closure:  Most of CDOT’s rockfall projects are located on mountain passes where often no viable alternate route exists. These sites usually require traffic stops in excess of 20 to 30 minutes as debris is blasted, hauled away, safety of the hillside is surveyed and single-lane, alternating traffic queues are cleared in both directions. These types of delays continue through a project’s duration as crews work above the highway drilling and installing rockfall mitigation features, knocking down loose rock as they construct. These projects often take two seasons to complete (a recent example of a similar project was on SH 133 McClure Pass in Pitkin/Gunnison counties; the project took 8 months to complete:  work was underway from October through November 2012 and then May through October 2013.

State Highway 3 is located in an urban setting where there is a viable alternate route (which adds no additional mileage to a trip into town, and only 1 mile or less if travelers are attempting to reach the Rivergate complex via Sawmill Road or the businesses just north of Sawmill). This adjacent alternate route will certainly add some time to a commute due to additional congestion; but a full closure of SH 3 will have the following benefits:

  • CDOT can complete this critical safety project in about one-third of the time, keeping the project to one construction season and avoiding impacts during next summer's tourist season; this dramatically shortened schedule is due to the fact that crews can work consistently through 10-hour days, six days a week; and rock debris, equipment (including a large crane) and work zone barriers can be left in place rather than cleared for traffic each hour or night or weekend.

  • The shortened schedule has enabled CDOT to conduct this work during a shoulder season and not in the height of tourist season (some minor work may be necessary in the spring of 2015).

  • Motorists do not have to endure lengthy delays for rock work and single-lane, alternating traffic configuration.

  • SH 3 traffic will not back up into US 160/550 to the south or in front of Rivergate Lane or SH 3 businesses, as it would if lengthy construction delays were present.

  • Could SH 3 be opened at night and/or on weekends?  The safety risk is too great and the time that it would take to return the roadway and the hillside to a safer situation each night and each weekend would create the need for a longer-duration project. Furthermore, if the highway were to be opened at night and on Sundays, it would still remain in a single-lane, alternating traffic configuration controlled by a signal and resulting in travel delays.

  • The project team is and will continue to make every effort safely possible to expedite this work and reduce the duration of the full closure.

Anticipated Travel Impacts:  Beginning Thursday, August 21, 2014, through November 18, 2014, the project will require a full road closure on the south end of SH 3. During the full closure, the alternate route will be US 160/US 550. (PLEASE NOTE: access to the Rivergate businesses, medical offices and residences will still be available from the north, via Santa Rita Drive or 8th Avenue—this alternate route adds only one mile, though travelers should add extra time for their commutes due to the added congestion on US 160/550 through Bodo.) The Carbon Junction Trail, which provides access to the Telegraph Trail System, will be open during construction; however, parking at the trailhead will not be available. Parking is available at the Big Canyon Trailhead further south and a temporary detour along the roadway is available between the two trailheads.

Questions? Comments?  The best way to stay up to date on project progress and impacts is to sign up for email and wireless (text) alerts. Go to CDOT’s web site at www.coloradodot.info and click on the green cell phone icon in the upper right hand corner of the page. Enter your information and choose “SH 3 Durango Rockfall” under the “Projects” list. The public may also call the project information line at (970) 759-1030 or write to [email protected].

*This safety project is receiving funding from RAMP, Responsible Acceleration of Maintenance and Partnerships. RAMP is better coordinating project expenditures and available funding. Under the RAMP program, CDOT will fund multi-year projects based on year of expenditure, rather than saving for the full amount of a project before construction begins. For more information, including a list of RAMP project requests, please see our website: http://www.coloradodot.info/programs/RAMP.