After lengthy closure, how is West Seattle Bridge holding up?

West Seattle’s forced exile ended eight months ago when the high bridge opened after emergency repairs. Has traffic returned to normal, and how is the bridge holding up?

I was looking at some pictures I took inside the damaged West Seattle Bridge during the two-and-a-half-year closure recently, and it got me thinking, how are those repairs doing, and what have the inspections been showing?

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Despite the discovery of a large hole Tuesday evening that caused the northbound ramp of State Route 99 over the West Seattle Bridge to close, the bridge is holding up great according to the Seattle Department of Transportation (SDOT).

I caught up with Kit Loo of SDOT this week. He’s the interim division director of roadway structures for the city. Eight months after the reopening, the bridge is doing great.

“There were no red flags that noted that the structure was not behaving the way that we predicted, based upon the repairs that we’ve done for the bridge,” Loo said.

SDOT started with monthly inspections inside the bridge and then moved to quarterly inspections because nothing looks out of line. Engineers are also monitoring all the sensors put inside the bridge daily.

“We actually had a pretty robust program, including evaluating the structural health instrumentation that we had put on the bridge as part of the repairs, and all those data points, as well as the physical inspection, have shown that the repairs are performing as expected,” Loo said.

So what does an inspection look like?

“Looking to see if there’s any development of any new cracks or extension or propagation of existing cracks that might be on the bridge,” Loo said. “Looking at the fiber wrap that we put on there to see if there’s anything de-laminating from the side of the walls and looking at the general health of the structure itself.”

Engineers also check the new anchor points for all the steel cables used to strengthen the span. The bridge is doing well enough that SDOT has moved to six-month physical inspection cycles and hopes to return to the standard two-year cycle soon.

What happens if any of those new sensors go off, indicating a potential issue with the bridge?

Loo said the first thing the engineers will check is the sensor. If it’s just one sensor, there could be a data issue. If it’s multiple, Loo said they have a plan put together.

“We may have a response team go out to the bridge to do a physical inspection to check to see if there are any problems with it, or if there are multiple signals and data training towards an issue, then we respond with the emergency response,” Loo said.

Engineers can also put eyes inside the bridge at any time.

“We do have video cameras that are installed as part of the health monitoring systems that allow us to peek inside the bridge in real-time to see if there’s something that raises to a level that we need to do something immediately,” Loo said.

And despite Tuesday’s ‘speed bump,’ there have been no major issues, which is great.

As for the loads on the bridge, Loo said there has been some extra freight travel with the opening of Terminal Five, but the daily commute has not returned to pre-closure levels.

Between 60,000-65,000 vehicles a day have been using the bridge so far this year. That’s way down from the nearly 100,000 vehicles a day that used the bridge before the closure.

Check out more of Chris’ Chokepoints.

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