Tuesday, June 30, 2009

Why the roadway has a bit of a wave

Over the past few weeks, our crews have been taking a look at exactly why the bridge is a little wavy. They are in the process of determining what will be done to fix it.

Data so far is pointing toward the undulations being a result of building and piecing the bridge together a section at a time. Could we have done the work any differently? Yes, but everything comes with a price.

Option One: Build at the Site

When WSDOT built the new west half in 1978-1982 much of the roadway work was completed at the bridge site. This process could have been used for the east-half replacement. The trade off was that the bridge would have been out of commission for up to three years.

Option Two: Build off site

The biggest goal of the east-half replacement project was to minimize the time the bridge was closed to traffic. This meant matching up sections that were built in different locations.

While each roadway section meets the required specifications of being within 1/8th inch over the length of sections, when connected together the overall roadway is a little wavy.

Many discussions took place, talking through what absolutely had to be done before we could safely open the bridge to traffic and what we could do later during short night time closures. Ultimately, we decided to reopen the bridge as soon as possible and work through the roadway issue later.

Thank you for your patience as we make adjustments to your new bridge.

1 comment:

Anonymous said...

The "waves" are not at the pontoon joints, they are at almost all of the intermediate spans between the cross beams of the new east half. The girder or deck camber calculations were probably in error.

Drive across it at 40-45 mph and you will notice it. You don't notice it on the west half.

Building the superstructure in the calm waters of Elliolt Bay at Todd Shipyards should have provided a much better environment for quality control than the stormy waters of the Hood Canal.