“The way I see it, we’re not going to have overruns”
State Representative Judy Clibborn, Chair of House Transportation
“There won’t be any cost overruns.”
Transportation Secretary Paula Hammond
“We don’t envision any cost overruns on this project.”
Pearse Edwards, spokesman for Governor Gregoire
How do you react to these statements? A little disbelief? We all know large public projects tend to grow in cost over initial estimates. This can happen for many reasons – materials costs can increase during construction, unforeseen obstacles can be encountered in the environment, errors or equipment problems can delay. Sometimes, politicians create unrealistic expectations to sell a project.
We’ve recently been through a construction boom. Materials prices skyrocketed for more than a decade, driving up costs and leading projects around the country underfunded. Now the bubble we were in is deflating, and projects that were priced during the boom are turning out to be a little cheaper than we’d thought. But that’s temporary – as planners planned for flat costs before the last boom, they’ll do the same for the next. If we’re near the bottom now, costs will rise again during construction, costing Seattle money we don’t have.
The market isn’t our only risk. When building underground, a contractor can’t see what’s ahead. Soil samples are taken before construction to better understand what’s being bored into, but they can’t find everything – a boulder or sand pocket can add days or weeks to the schedule. In this project, water pressure will also be a consideration. The downtown transit tunnel goes slightly below the waterline, but a viaduct tunnel would go much deeper, meaning this tunnel boring machine will also have to contend with high pressure seawater.
Recent tunnel construction in this area has shown that with our geology, even without being under the water line, tunnel boring machines often encounter problems. Sound Transit’s twin Beacon Hill tunnels bored so much more slowly than anticipated that they ate away the entire float time, six months of padding, in Link Light Rail’s schedule. Instead of an expected 50 feet a day, the machines bored closer to 20. Had they been any slower, Link would have been delayed.
As this is being written, two of the four tunnel boring machines digging sewage pipes for the Brightwater waste treatment plant are stalled completely. These will take so long to repair that instead of standing by, affected workers were simply laid off. If this happened during viaduct tunnel construction, it would not only increase costs, but also increase risk to drivers, as the unsafe, elevated viaduct structure would be left standing until the replacement was complete.
The Brightwater and Link tunnel borers were also far simpler than what’s proposed for the viaduct. In smaller bores, only a single rotating cutting head is necessary, but a machine this large has to have two – a center cutting head, and a giant ‘ring’ cutting head around it, rotating in the opposite direction. Our risk of equipment failure or delay increases with the complexity of the hardware.
With statements from our state leaders like those above, and the risks they aren’t talking about, do you have any confidence that this tunnel is affordable?