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I-70 Twin Tunnels


The widening of the Veterans Memorial Tunnels, located along mountainous Interstate 70 near Idaho Springs, Colorado, is a key piece of the Colorado Department of Transportation (CDOT)'s USD $106 million I-70 improvement project. The 700-foot (215-meter) tunnels are designed to improve traffic flow along a corridor notorious for gridlock and bottlenecks, which cause lengthy delays during heavy travel times, particularly for vacationers and skiers heading to-and-from Denver, 30 miles (50 kilometers) west of the tunnel. 

Widening the tunnel and improving the lighting helped to eliminate the “black hole effect,” which caused many motorists to slow down when entering the tunnel. The lighting design utilized the latest in low-consumption LED technologies. To meet the construction deadline, two crews worked from both portals simultaneously, eventually meeting near the middle. Controlled blasting adjacent to the old tunnel was used to gradually widen it. Traffic is being re-routed around the tunnel during construction. 

Construction of the eastbound tunnel was completed in December 2013, and the westbound tunnel was completed in December 2014. 

As a subconsultant with Yeh & Associates for the Atkins Global design team, WSP USA was responsible for preparing the plans, specifications and quantities for all aspects of the underground work, including design of the excavation support systems, the sequences of excavation, blasting vibrations, drainage, fire and life safety, final lining and lighting design.

In addition to the Denver office, which provided civil and geological engineering, planning, permitting, and project management support, we drew on technical resources from offices across the U.S., including: 
• Boston – lighting, ventilation and fire/life safety 
• Philadelphia – blasting 
• San Francisco – tunnel excavation support and sequencing, groundwater control and structural, and quantity estimates 
• Seattle – tunnel lining selection and groundwater control