WASHINGTON STATE DOT The Euclid Creek Tunnel is one of several planned storage tunnels designed to relieve overflows in the Northeast Ohio Regional Sewer District. The tunnel can hold approximately 60 million gallons of combined stormwater and wastewater. Mott MacDonald served as the lead consultant on the project. The boring machine for the Alaskan Way Viaduct Replacement Program in Seattle reached more than 200 feet below grade to create a tunnel nearly 58 feet wide that carries a 1.7 mile double-deck highway. In conjunction with the Washington DOT, Mott MacDonald served as the project management assistant consultant. BY SAMUEL GREENGARD TUNNEL VISIONS ADVANCES IN TUNNELING TECHNOLOGY ARE ALLOWING ENGINEERS TO BUILD WHERE THEY COULD NOT BUILD BEFORE E ngineering has always been about overcoming obstacles. In order to build a better and more functional world, humans have long constructed things to enable and simplify myriad tasks. Tunnels certainly fit this worldview. Tunnels move everything from vehicles and water to people and digital communications. Yet, today, as engineering methods improve and technology advances, tunneling is extending to places where it was not possible to build in the past: under cities, through mountain ranges, even under oceans. NOVEMBER / DECEMBER 2019 ENGINEERING INC. 13