Saturday, May 7, 2016

Engineering experts raise quality concerns over Honolulu’s rail construction

With Gina Mangieri of KHON Channel 2 News Always Investigating...
“One of the cracks in this area was pretty alarming and it was along the line of the segment,” he pointed out.

Other concerns have to do with the amount of rust, starting with tracks that the city bought early to hedge on steel price.
“Basic rust is not a problem. It’s actually a protective coating that, when the rail starts running, it will clear a lot of it,” Prevedouros explained.
But when it gets installed, more problems can arise. “One of the issues is that it creates problems with the labor that tries to install them. They may need extra protection because when you’re bolting them, there may be excessive dust of rust,” Prevedouros warns, which can be dangerous when inhaled.
Other rust hot-spots lie in the rebar forms that start each pillar.
“Here we see the rebar for the support columns,” Prevedouros pointed out, “and I am a little worried that it’s quite rusty, because when you pour the rebar around it, it creates problems with adhesion of the concrete to the rebar itself. In the long term, it may cause spalling problems, delamination problems.”
That’s not the only worry about the pillars, especially in certain parts of the route.
“The problem in general with Waipahu is it was famous for springs and underneath water caves,” Prevedouros said, “and this is a very heavy, very long bridge. Some of these pylons may have settlement issues. There have been reports that at least a couple of them have issues of settling. They’re going into the ground. Beyond a few inches, it becomes tremendously stressful for the structure and we probably need to add more to support the bridge.
“It could be sudden, but it could take several years,” Prevedouros added. “First, we’ll hopefully see cracks, but then we’ll have to react to it before we have a collapse.”
Quick reactions have to be at the ready on other key jobs along the building process, like when crews go to snug the segments together with cables in something called “post-tensioning” — something that brought a near disaster near the Banana Patch — which was memorialized in HART’s report as Span 258, NCR 509.
“They had a failure with a segment they were trying to post-tension it, which is the process this thing is getting built,” Prevedouros said, “but the tendons failed. There was essentially a minor collapse. Now they’re shoring it up to try to connect it with the two pieces to the left and the right. The whole segment seems to be supported from the bottom and they’re trying to fix the situation.”
“Does it run a future safety risk?” Always Investigating asked.
“The problem is now, by having this failure, it is costing a lot of time and resources to fix it,” Prevedouros said. “But they will fix it in a way that will probably be quite durable.”