Lower Fourmile Canyon Drive Reconstruction Options

Lower Fourmile Canyon Drive Reconstruction Options

After collecting feedback from residents and other interested parties regarding flood-related permanent reconstruction of Fourmile Canyon Drive, Boulder County Transportation learned that many would like the designs to eliminate the need for removal of soil and rock from the uphill side of the road. In response, the county and its engineering team created an option wherein earth removal from this side of the road would be unnecessary. This option was presented for comment in late 2015 and is available for review below.

The design team has used public input and updated information to create a third set of designs. This set of designs is available below. These designs were presented an open house on May 25, 2016.

Our goals for rebuilding the two flood damaged sections of lower Fourmile Canyon Drive in such are to:

  • Withstand future flooding.
  • Make the road safer.
  • Reduce the impact of flooding on residents adjacent to the roadway and creek.
  • Maintain the special visual, environmental, and community character of the canyon by minimizing construction impacts.

Design Trade-offs
It’s not possible to rebuild Fourmile Canyon Drive so that it’s safe for travel by all modes and resilient to future weather events without either moving the road away from the creek into the hillside, or strengthening the creek-side of the road.

In all design options, the roadway includes an approximate 1-foot downhill lane shoulder, two 11-foot travel lanes, an approximate 4-foot uphill lane shoulder and a drainage ditch. The primary function of the uphill shoulder is to hold and convey water that is coming down the hillside and prevent it from inundating the road. It also serves as a catch zone for falling rock and debris. In addition, the shoulder provides space for emergency services vehicles and a place for disabled vehicles to get out of the roadway.

Previous Design Options:

South Section of Construction – 1033 to 1653 Fourmile Canyon Drive

Comment Form

North Section of Construction -Just South of 4324 to Salina Junction

Comment Form

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Phone: 303-441-3520
Fax: 303-441-3598

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PO Box 471
Boulder, CO 80306


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