ROB CARSON; The News Tribune
Published: June 25th, 2006 01:00 AM
Engineers and managers at Tacoma Narrows Constructors were still puzzling Saturday over how they could have been so wrong about the height of the first shipload of deck sections for the new bridge.
The bridge builders expected the ocean transport vessel the Swan to slide under the side span of the existing Narrows bridge Friday with 36 feet to spare. Instead, the top of the load grazed the underside of the bridge deck, forcing the ship to turn around and return to Commencement Bay.
The problem and the solution are simple, said Erin Hunter, a TNC spokeswoman: The ship was riding too high in the water and ballast needs to be added to lower it.
What is not so simple, she said, is how engineers were so far off the first time.
“What we’re looking for is, where was the disconnect?” she said. “We’re evaluating the situation so it doesn’t happen again. We’re taking all the measurements and calculations and reassessing and recalculating them. We’re checking everything and then double-checking it and then checking it again.”
Hunter said no damage was done, either to the bridge or the new deck sections. And she said the mishap will not affect the lifting schedule, because the loaded ship was to stay under the existing bridge for several days before lifting began.
No date has yet been set for the next attempt to bring the ship into the Narrows, Hunter said.
The lifting operation is expected to begin within the first two weeks of July.
Nailer99 wrote:Maybe it was like when Nasa and the JPL lost the Mars probe- one of them did their calcs in Metric, and the other one did theirs in imperial.....
Actually, I wouldn't be at all suprised if that was the problem here!
Hey! If they keep that up, we might have a great new drift dive site!!! If nothing else, we could collect stuff - it'd be like Christmas!!! How deep is it below the narrows anyway? I'm totally ignorant - is it really deep, closed-circuit only, or what?
Sounder wrote:Hey! If they keep that up, we might have a great new drift dive site!!! If nothing else, we could collect stuff - it'd be like Christmas!!! How deep is it below the narrows anyway? I'm totally ignorant - is it really deep, closed-circuit only, or what?
There's already something really cool down there ... the old bridge, Gallopin' Gertie ... and it's a national monument. You can find parts of it in water as shallow as 35 feet or so. Before the construction, it was a popular dive ... and will be again after the construction is ended. Unfortunately, building the new bridge caused significant damage to portions of the old bridge.
Sounder wrote:Hey! If they keep that up, we might have a great new drift dive site!!! If nothing else, we could collect stuff - it'd be like Christmas!!! How deep is it below the narrows anyway? I'm totally ignorant - is it really deep, closed-circuit only, or what?
There's already something really cool down there ... the old bridge, Gallopin' Gertie ... and it's a national monument. You can find parts of it in water as shallow as 35 feet or so. Before the construction, it was a popular dive ... and will be again after the construction is ended. Unfortunately, building the new bridge caused significant damage to portions of the old bridge.
... Bob (Grateful Diver)
Yes, based on the initial reports from Underwater Admiralty Services, I wouldn't expect much of the old bridge to remain. I know the base of the pilings are buried in many tons of rock. I'm hoping the old bridge sections on the west side from about 60-90 feet are intact.
