CO FLAP SH 5(1) Mount Blue Sky Highway

PROJECT NUMBER and NAME: CO FLAP SH5(1), Mount Blue Sky Highway PROJECT DESCRIPTION: The Mount Blue Sky Highway Project proposes to reconstruct 0.7 miles of Colorado State Highway (SH) 5 in Clear Creek County, Colorado. The project is located approximately 50 miles southwest of Denver in the Arapaho and Roosevelt National Forest. SH 5 is designated a Scenic Byway and provides access to the top of Mount Blue Sky which is the highest paved road in the United States.

The project area is adjacent to Summit Lake Park located at 13,000 feet above sea level. The area receives on average 292 inches of snowfall per year with temperatures ranging from 65 to -40 degrees Fahrenheit. The project traverses between United States Forest Service and Denver Mountain Parks Lands. The project area is distressed with major subgrade failures.

The roadway was originally constructed across a wetland complex causing disruption to both surface and subsurface water flow which has led to degradation of the underlying permafrost. The Permafrost degradation and on-going solifluction have caused major damage to the roadway including settlement, subgrade failure, and cracking.

The project scope includes roadway reconstruction with a pavement section supported upon an air convection embankment (ACE) to improve subsurface drainage, minimize permafrost degradation, and stabilize the roadway. The ACE will be constructed to an approximate maximum depth of 4’ to 5’ and will consist of rock ranging from 4” to 12” in diameter.

Additional salient project features include removal and replacement of culverts, installation of an aquatic organism passage culvert, vegetation salvage and placement, sub excavation, aggregate subgrade, and asphalt paving.

PRINCIPAL WORK ITEMS: 20,000 cubic yards of embankment construction including rock embankment 2,000 tons of aggregate base 2,000 tons of asphalt concrete pavement 200 linear feet of metal pipe culverts 4000 square yards of salvaging/placing conserved topsoil 5 miles pavement markings, type b ANTICIPATED SCHEDULE: It is anticipated construction will start approximately July 2024 and finish approximately October 2025. ESTIMATED COST RANGE: The anticipated cost range is between $5,000,000 and $10,000,000.