The difficulties of projecting costs for big tunnel projects

Cost overruns on big infrastructure projects are common but may be even worse for tunnel projects, as the case of the California high-speed rail project may soon illustrate:

“You have an 80% to 90% probability of a cost overrun on a project like this,” Flyvbjerg said. “Once cost increases start, they are likely to continue.”…

Although some large tunnels have been constructed elsewhere without difficulty, including the 3,399-foot Caldecott Tunnel in the Bay Area, others have encountered costly problems.

The 11-mile East Side Access tunnel in New York City, for example, is 14 years behind schedule, and the tab has grown from $4.3 billion to $10.8 billion. Boston’s 3.5-mile Big Dig was finished in 2007 — nine years behind schedule and at nearly triple the estimated cost.

Digging stopped on the 2-mile Alaskan Way tunnel under Seattle when a boring machine broke down in December 2013 and had to be retrieved for repairs, causing a multiyear delay with an unknown cost overrun.

The bullet train will require about 20 miles of tunnels under the San Gabriel Mountains between Burbank and Palmdale, involving either a single tunnel of 13.8 miles or a series of shorter tunnels.

As many as 16 additional miles of tunnels would stretch under the Tehachapi Mountains from Palmdale to Bakersfield.

All told, this is a major project that might just draw attention from the public and scholars for decades to come. Is it possible to even finish it? What will be the end cost? Will it enhance transportation and life in California? There is a lot at stake here and big costs will not help. From the article, it sounds like part of this is due to falling behind schedule – this adds more money as the project takes more time and costs tend to go up over time – and is also due to the unique geological features of California – fault lines and possible earthquakes – which produce additional complications.

I’ve seen numerous people suggest that projects like these illustrate how difficult it is for the United States of today to complete major projects. This may be needed and/or helpful but a lot of good things have to happen before the line even becomes operational.

One thought on “The difficulties of projecting costs for big tunnel projects

  1. Pingback: The infrastructure devil is in the (financial) details | Legally Sociable

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