Idaho DOT's First Design-Build Project Wins Engineering Excellence Award

The reconstruction of Idaho 44 from Linder Road to Ballantyne Lane, completed in October 2013, won an award from the American Council of Engineering Companies of Idaho at their Engineering Excellence awards luncheon April 14 in Boise. It was the Idaho Transportation Department's first design-build project. Central Paving was the contractor and Horrocks was the lead designer.

The segment of Idaho 44 between Linder Road and Ballantyne Lane is a major east-west commute route in the Treasure Valley and the primary access to Idaho's Eagle Island State Park. Every day 19,000 motorists drive through the Idaho 44/Linder Road intersection. Traffic in this area is expected to increase to 30,000 cars each day by 2030.

To accommodate the anticipated increase in traffic, ITD needed to widen the highway from three lanes to five lanes, and partnered with ACHD to improve the Idaho 44/Linder Road intersection. The newly widened intersection has two through lanes in each direction on Idaho 44, room for future double left-turn bays onto Linder Road and right-turn lanes at all four sides of the intersection. Idaho 44 was expanded to five lanes in the two-mile segment from Ballantyne Lane to just west of Linder Road.

The project also featured a few challenges and innovations, such as integrating a 700-foot long gravity retaining wall with a large irrigation canal instead of a large box culvert, as initially planned. The design-build firm also chose to use a CRABS (Cement Recycled Asphalt Base Stabilization) rather than full reconstruction, as their materials analysis proved CRABS to be cheaper, quicker, and provided the same lifespan.

Design-build allowed the design and construction teams work together under a single contract with the department. The Idaho 44, Linder to Ballantyne project was unique because ITD brought Central Paving, the construction contractor, on board while Horrocks Engineers was developing the project's design plans.

This partnership allowed the construction contractor to work hand-in-hand with the engineering firm throughout the project. The construction contractor was able to contribute its knowledge of best practices and constructable methods throughout the design process, which allowed for a speedy resolution of issues.

The project was completed on time and within budget.