Urban tunnel replaces viaduct, improves safety
Earthquake sensors, automatic barriers and real time monitoring systems are all part of a scheme to make a major Seattle traffic artery safer, by taking it underground. Huw Williams reports. Seattle's metropolitan area of 3.5 million people, like much of the western seaboard of the United States, lies in an earthquake zone. In Seattle's case, the city and its hinterland sit atop a complex...