Mount Baker Ridge Tunnel
historic place
The Mount Baker Ridge Tunnel, in Seattle, King County, Washington, is a notable engineering achievement. The original twin tunnels were completed in 1940. These 29-foot diameter bores were then the world's largest soft-earth tunnels, excavated through heavy blue clay. In 1989, a new, larger tunnel opened north of the originals. This 63-foot diameter expansion tunnel became the world's largest soft-soil tunnel at that time. It features three levels for buses, general traffic, and a pedestrian and bicycle path. Today, the Mount Baker Ridge Tunnel complex carries Interstate 90 and the Link light rail's 2 Line. It was listed on the National Register of Historic Places on July 16, 1982. Its eastern entrances, adorned with murals, are a City of Seattle landmark. This site illustrates a key development in Seattle's transportation infrastructure.