Pacific Maritime Magazine - Marine Business for the Operations Sector

A Tale of Tunnels

 


The keynote speaker at the California Maritime Leadership Symposium in Sacramento late last month was Leslie Blakey, Executive Director of the Coalition for America’s Gateways and Trade Corridors.

Ms. Blakey’s presentation touched on the sad state of the country’s interior infrastructure- notably its roads. She presented data from the World Economic Forum Global Competitiveness Report, 2013-2014 showing that the US is 15th in the world in global infrastructure, behind frontrunners Hong Kong and Singapore but also behind Korea, Spain and Luxembourg.

Seattle provides us a stark example of why we are in our current state.

In 2001, an earthquake hit Seattle’s Alaskan Way viaduct, which survived virtually undamaged because of elegant design and competent construction. While the earthquake caused no lasting damage to the span, downtown interests, construction labor and other special interests used it as an excuse to tear down the viaduct to free up views to the bay.

After a decade of “Seattle Process”, construction on an underground tunnel began in July, 2013. While the viaduct had a capacity of 140,000 vehicles a day, and served as a major thoroughfare for traffic heading between Seattle’s north and south industrial areas, the tunnel currently under construction will have a capacity of 80,000 vehicles per day.

The tunnel project almost immediately began experiencing construction delays related to work stoppages and frequent problems with the massive $80 million tunnel boring machine.

The machine, nicknamed “Bertha,” has only completed a fitful 1,000 feet of the 2-mile tunnel, and currently sits idle while engineers devise a way to reach her clogged cutting head 130 feet below the streets of Seattle.

In stark contrast to the Seattle tunnel project is the Transbay Tube.

The Bay Area Rapid Transit System (BART) averages 400,000 riders a day. Half of those go through the trans-bay tunnel, connecting Oakland and San Francisco.

The 3.7-mile Transbay Tube sits in a trench excavated into the seabed as deep as 135 feet below the surface. It is protected by a covering layer of armor rock, or riprap, to keep errant ships’ anchors and other unexpected heavy objects from coming into contact with the tube, which has been operating as designed with no major incidents since it opened in 1974. In late January of this year, a 965-foot-long container ship lost power and dropped anchor to keep the ship from drifting, approximately 1,200 feet southwest of the Transbay Tube. Within a few minutes, power was restored to the ship, the anchor was retrieved and the vessel continued on to the Port of Oakland.

The Coast Guard said it did not appear the ship’s anchor hit the tube, but the transit agency stopped service in the tube briefly while the tube was inspected as a safety precaution.

No injuries were sustained on the ship, and the event was... uneventful, but it served to call our attention, briefly, to the Transbay Tube – a daring engineering project completed for $180 million 40 years ago, or about $1 billion in 2014 dollars.

The Seattle tunnel, originally scheduled to open in 2015, is budgeted at more than $2 billion and the total viaduct replacement was estimated at more than $4 billion – before the current delay. The Port of Seattle has committted $300 million. Meanwhile, the Alaskan Way Viaduct continues to operate safely as designed, while Bertha sits idle for at least the next two months.

By the way: There’s already a tunnel under downtown Seattle. It’s a mile long and 30 feet wide, was built for $1.5 million ($40 million adjusted) and has seen continuous daily use since 1904. The Burlington Northern train tunnel was dug, as one Seattle Times columnist put it, “...by 350 guys with shovels.”

 
 

Powered by ROAR Online Publication Software from Lions Light Corporation
© Copyright 2017