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 Author: crow
PostPosted: Mon Oct 23, 2017 2:48 pm 
Bridges aren't rigid. When entering or leaving the 90 Bridge we feel a thump created by this strip of concrete that is lower than the rest of the road surface; to the left of it is Hudson and on the right is the bridge. The south end has the same problem. These will be the first of the next 2 fixes to the bridge. Well, there is still the matter of an engineering report as to whether up to half of the bridge will need to be torn out and redone correctly. But first this next, critical fix that is scheduled to begin Oct 30 and will entail lane closures according to the DOT.

Below that line of concrete is the Bridge Joint, preformed foam pieces that separate the flexible bridge from the rigid hillside and existing rigid roadway. The photo shows the foam pieces being installed before the concrete road surface and end of bridge is placed. Hudson Street was then brought to the structure holding the foam. Because the concrete covering the foam pieces is lower than the road surface water (salty water in winter) collects and leaks down onto and around the foam so the manufacturer of the foam pieces will not bond (insure) them until it's fixed.

The 2nd fix before winter sets in is that the whole bridge surface will get a sealer (probably some kind of liquid vinyl says the DOT) but before that the bridge surface will be washed to remove salt from last winter. In the photo below we can see the gravel (aggregate) of the concrete showing on the surface and large cracks. This tells the inspectors that the concrete was not finished (troweled) properly to seal the surfave so the water seeps into the concrete and leaves salt crystals in the concrete. When salt builds up in the concrete the surface cannot be patched because new concrete will not bind with the salty concrete. This was one of the problems with the old bridge so that by the time it was torn down there were holes in the concrete that allowed us to see the ground 50 feet below, yes holes in the driving lanes.
The parallel cuts I assume are for traction so look between the grooves. The cracks, of which there are many need to be sealed to prevent freeze damage and a deeper infiltration of salt.

Bridges aren't rigid rather they need to shake, shudder and bounce; without a release for the vibrations and frequencies that traffic produce the bridge would soon crumble apart so the girders and roadway just sit there unattached to anything, not below nor at the ends.

Two previous articles can be read HERE and HERE. and many more using the search term "90 Bridge" without the quotes.

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