Bertha isn’t Seattle’s first major tunnel project. Almost 100 tunnels totaling 40 miles lie beneath our city, including the record-setting Great Northern Tunnel, built in the beginning of the 20th century. Let’s see how that mile-long train tunnel compares to Big Bertha’s tunnel.
Great Northern Tunnel
The Great Northern Tunnel runs for one mile beneath downtown Seattle, stretching from the waterfront to 4th Ave. S and Washington St. It was built, much like Bertha’s tunnel, to reduce traffic on Alaska Way.
Great Northern and the Northern Pacific Railroads split the cost of construction, and although the tunnel’s owner has since changed (it now belongs to the Burlington Northern-Santa Fe Railway), the tunnel still sees regular train traffic. If you’ve ever ridden a train into or out of Seattle, you’ve probably used this tunnel.
Three hundred and fifty workers built it using pickaxes, shovels, and wheelbarrows. The miners divided into two teams, started at opposite ends, and met almost perfectly in the middle. The two tunnels were connected on October 26, 1904 at 5:55 p.m., and two months later, the rest of the tunnel was complete and ready for use. At the time of completion, it was the largest tunnel in the country (although not the longest).
While digging 140 feet below the First Presbyterian Church at 4th Ave. and Spring St., the miners discovered a 2,000-year-old prehistoric forest. They found one preserved tree more than three feet in diameter.
Local historian Michael Sullivan described the Great Northern Tunnel: “What would happen is you’d come through the Cascades and then you’d drop dramatically down. You’d be able to see the ocean, see the Pacific, and then you’d plunge into this blackout moment and then pop up in the middle of this city and here’s this great city of the Northwest that you’d arrive at. So it was very theatrical. It created a great dramatic kind of moment, you know?”
Big Bertha (Alaskan Way Viaduct Project)
Big Bertha, Seattle’s infamous tunnel-boring machine, was built in Japan and shipped to Seattle, where it has since spent its time drilling (and breaking). Bertha’s mission: create a tunnel to replace the sinking Alaskan Way Viaduct.
Bertha is mostly automated, but it still requires 25 workers at a time to keep the 7,000-ton machine moving forward. Bertha will remove approximately 850,000 cubic yards of fill by the time it finishes digging.
The original completion date was scheduled for late 2015, but delays have pushed that back to March 2018, and a recent sinkhole has stopped Bertha’s progress once again. Although Bertha’s drilling speed can reach 35 feet/day, its 27 months of delays have reduced its progress to approximately 5.5 feet/day.
[table caption=”” width=”600″ colwidth=”200|200|200″ colalign=”left|center|center”]
,Great Northern Tunnel,Big Bertha
Construction Length,”April 4, 1903– December 1904 (1.5 years)”,”July 30, 2013–early 2018+ (4.5 years)”
Cost,$1.5 million ($38 million today),$4.25 billion+
Dug By,”350 workers using pickaxes, shovels, and wheelbarrows”,Big Bertha
Tunnel Height,28 feet,57.5 feet
Tunnel Width,30 feet,57.5 feet
Tunnel Length,1 mile,1.7 miles
Digging Speed,18 feet/day to 12 feet/day,35 feet/day
Overall Speed (including delays),10 feet/day,5.5 feet/day
The Alaskan Way Viaduct Tunnel is bigger than the Great Northern Tunnel, in width, height, and length. And Bertha digs almost three times as fast as that 20th-century team of pickaxes and shovels—but only when Bertha is running.
When you look at the months and months of delays, we have to hand it to the 1903-1904 tunnel. 10 feet/day, compared to Bertha’s measly 5.5 feet/day. Bravo, you early Seattleites!