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Long-Lasting Pavement Solution for an InterstateGuide Helps Washington State Meet Project GoalsJ E F F R E Y S . U H L M E Y E R

On Interstate 5 (I-5) northbound betweenBurlington and Bellingham, Washington,

old concrete panels beneath the asphalt werecausing severe transverse cracking along astretch of 11.6 miles, or 23.08 lane miles. TheWashington State Department of Transporta-tion (DOT) placed hot-mix asphalt (HMA) overthe faulted pavement in the early 1990s, andmaintenance crews sealed large cracks as a tem-porary solution in 2009 and 2010.

Looking for a long-lived, cost-effective solu-tion, Washington State DOT agreed to pilot theprocedures in the guide produced by the secondStrategic Highway Research Program (SHRP 2),Using the Existing Pavement In-Place and Achiev-ing Long Life,1 during the I-5 Joe Leary Sloughto Nulle Road Vicinity project. A web-baseddecision support tool, the guide contains pro-cedures for identifying when pavements can beused in place, as well as approaches to incorpo-rate the original pavement material into the newstructure.

Project Goals and OptionsWashington State DOT’s goals were to providea long-lasting pavement solution for the I-5rehabilitation, advertise the project within fourmonths, and hold expenditures within a budgetof $25 million. The SHRP 2 guide provided avaluable reference in speeding up the pavementselection and scoping process and in identifyingthe best strategies for rehabilitation with in-place pavements, leading to three viable options:

u CSOL—crack and seat the concrete withan 8.4-inch asphalt concrete overlay;

u Asphalt rebuild—pulverize the pavementin place for an 8.4-inch crushed surfacing basecourse (CSBC) with a 13-inch hot-mix asphalt (HMA) overlay; or

u Concrete rebuild—place a 4.2-inch CSBC, overlay with 4.2inches of HMA, then overlay 13 inches of portland cement concretepavement.

Applying the ToolTo meet the project schedule, Washington State DOT immediatelystarted the pavement design and the preparation of technical docu-

ments for the contract. The decision supporttool provided the technical information forimplementing the CSOL method, an alternativethat the agency had not used previously; thisincreased management’s comfort level.

The project team relied on the tool’s resourcedocuments, especially the best practices andspecifications. The guide quickly and conciselyeducated practitioners at a detailed level onnational and international practices; althoughcorrespondence with other agencies was noteliminated, the decision support tool focusedthe project team’s efforts.

By the time the I-5 project went to Washing-ton State DOT engineers, the team was confi-dent in its success. The agency was able todevelop the CSOL technical documentation andcontract specifications within the time frameand advertised the project in the required fourmonths.

Cost SavingsWashington State DOT awarded the project inFebruary 2011 with design–build procure-ment. The 4.2-inch HMA overlay was removed,the pavement was cracked and seated, and an8.4-inch overlay of HMA applied. On 5 lanemiles, after the 4.2-inch HMA overlay wasremoved, the pavement received a dowel barretrofit and 4.2 inches of HMA overlay. Mis-cellaneous repairs also were made to north-bound and southbound ramps. The total initialcost of the project to the agency was $14.553million, with an average cost of $582,000 perlane mile.

By identifying additional pavement rehabil-itation alternatives, the SHRP 2 decision sup-port tool assisted Washington State DOT in

achieving significant savings initially and over the pavement’s lifecycle. The CSOL method saved Washington State DOT 19 percentin initial agency costs, 16 percent in agency costs for the roadwaylife cycle, and 28 percent in user costs over the life cycle. In addi-tion, the method reduced construction-required lane closures by43 percent.

The author is State Pavement Engineer, Washington StateDepartment of Transportation, Olympia.1 www.trb.org/Main/Blurbs/168146.aspx.

Old concrete panels beneath I-5 inWashington State caused severecracking in the roadway (top).Washington State DOT piloted a web-based decision support tool for in-place pavement recycling and seatedthe concrete with an asphalt concreteoverlay (bottom).

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