History of the Alaskan Way Viaduct
By Curt Cunningham

The First Seattle Viaduct

Seattle has one of the deepest harbors on the West Coast. The hillside which Seattle is built upon used to drop sharply into the bay. Pioneer Square was once a small island, and the area from King St. south to Diagonal Ave. S. was once a tide-flat. By 1900 this area had been filled in. Diagonal Ave. S. which was known as Seattle Boulevard in the 1890's, follows the old shoreline.

Before the tide-flats were covered, the road from the south ran along the foot of Beacon hill and from Diagonal Ave. S. north for about 2 miles the road ran along a narrow strip of land between the beach and the hill. The road came into town near 8th Avenue. This 2 mile section was known as the "Beach Road." This road was originally called Tobin's Mill Road and was built in 1854 between Yesler's mill in Seattle and Tobin's mill in Renton.

In 1886 the Beach Road was moved onto a newly completed wooden viaduct which began at 8th Ave. and Charles St. and continued south to Airport Way S. and Diagonal Ave. S. a distance of about 1.5 miles. This viaduct was called the Grant Street Bridge. The Grant Street Bridge was notorious for accidents, murders, and many other forms of foul play. This is was where the Saloons and brothels, which were built on pilings were located. The slaughterhouses which were also built on pilings were located along this stretch of road. The Grant Street bridge was also the principle thoroughfare leading into and out of Seattle. The bridge lasted until about 1900 when the tide-flats north of Spokane St. were filled in.

The Pacific Highway

When the Pacific Highway was designated in 1913 the route leading into Seattle came up the valley from Tacoma and crossed the Duwamish at Allentown and followed the old river channel to where the Boeing Airplane museum now stands. From Allentown the highway followed the old Military Road to the foot of Beacon hill at Airport Way. At Nevada St. the highway made a left and followed Nevada St. to 6th Ave. and turned right and followed 6th Ave. into town.

In 1913 the Duwamish Waterway project began. This project straightened out the river and filled in the old channel. From 1913 to 1920 the rest of the tide-flats were filled in. In 1915 construction began on a new highway from the Green river at Renton Junction (Tukwila) to downtown Seattle. This is when E. Marginal Way was built. The road was paved not long after its completion and the concrete paved Pacific Highway from Tukwila to Seattle was finished by 1919. The Pacific Highway now ran up E, Marginal Way to Alaskan Way and into Seattle.

The next change was in the late 1920's when the Pacific Highway was undergoing the transformation to a 4-lane modern roadway. In 1928 a new 4-lane Pacific Highway was opened between Tacoma and Seattle and this new highway came down into the valley from Seatac and connected to E. Marginal Way about a mile north of Allentown. This section is now known as Tukwila International Boulevard. This new 4-lane highway continued north on E. Marginal Way and at Georgetown the highway veered to the right and traveled into town on 4th Avenue.

In 1950 the Pacific Highway was routed onto West Marginal Way about a mile northwest of Allentown and crossed the Duwamish river on the 1st Ave. bridge about a half mile southwest of Georgetown and then continued north into town on 1st Ave. South. At Dearborn St. the highway veered to the left onto Railroad Way S. to Alaskan Way. Railroad Way S. was originally the old right-of-way of the Seattle & Walla Walla railroad which led to their King St. coal dock in the late 1800's.

The Alaskan Way Viaduct

Building a major interstate highway through Seattle was challenging for the engineers. Seattle is located between two large bodies of water; Puget Sound and Lake Washington. The land in-between is composed of steep hills running in a north-south direction and were created during the Ice Age. This left the highway department with few choices on where to put the new Seattle expressway.

By the late 1940's traffic in Seattle had become so bad it had become an major issue. The citizens were tired of the gridlock and began to call for a solution. The planning stages of the project took years to come to fruition and when the construction was to commence, it was welcomed by the public as the best way to end the nightmare.

The Alaskan Way viaduct was a 2 mile concrete elevated, double-decked 4-lane highway. The structure was built in three phases and work began on February 6, 1950, and it was completed on April 4, 1953. The viaduct was built along the waterfront above the surface streets, which allowed vehicles and people to pass underneath it. At first Alaskan Way was elevated from S. Holgate St., to Bell St. near the Pike Place Market. Before the tunnel was completed cars came off the viaduct onto Western Ave. and turned right onto Wall St. to connect with Aurora Avenue.

On July 24, 1954, the almost half mile long Battery Street tunnel opened for traffic. This tunnel made a direct connection between the viaduct and Aurora Avenue. This is when Highway 99 became an expressway through downtown Seattle.

On September 3, 1959 the southern extension to the viaduct was opened for traffic. This new structure was between S. Holgate St. and S. Hanford Street. The highway was supposed to remain elevated to the south side of Spokane St., but the cost prohibited construction and the roadway crossed over Spokane St. on a bridge instead. 

In 2001, the viaduct was damaged by the Nisqually earthquake. After a thorough inspection the structure was found to be sinking in some places and repairs were quickly made. The repairs proved to be only temporary and the structure continued to fail. It wasn't too long afterwards that plans began to replace the failing structure. It took a few years to decide on what to do, and the option which was chosen was to dig a tunnel under the city. This tunnel needed to avoid the railroad tunnel which runs under the city from Pike Place Market to King Street Station.

The initial phase of demolition and removal of the southern end of the viaduct began on October 21, 2011. This was to make room for the south portal. In 2013 a boring machine named "Bertha," began its journey under the city to Aurora Avenue. For the commuters in Seattle, it was 6 long years before construction was completed. On January 11, 2019 the Alaskan Way viaduct was permanently closed, and the new tunnel was opened for traffic on February 4, 2019.

Demolition of the Viaduct began on February 15, 2019 and the work was completed on November 15, 2019.