Embarrassing: Another bridge closed due to structural failure

[Ban my account ffs!]

http://www.usatoday.com/story/travel/destinations/2013/09/25/interstate-43-bridge-closed-wisconsin/2873307/

One of the piers holding up the I-43 bridge over the mouth of the Fox River near Green Bay, Wisconsin (named the Leo Frigo Bridge) has apparently suffered some kind of failure, causing it to settle 3 feet, which allowed the bridge deck to sag.  The bridge has been closed indefinitely pending repairs.

It's time for a hike in the gas tax and a national infrastructure bank!





The defeatist attitude of some commenters is pretty telling.  "We just can't afford to replace this!"

[Grumpier Than Uncle Joe]

It's time for a hike in the gas tax and a national infrastructure bank!

If we stop bleeding $2 billion a week overseas in Afghanistand and Iraq that bridge would have been repaired long ago.

[angus]

It's time for a hike in the gas tax and a national infrastructure bank!

If we stop bleeding $2 billion a week overseas in Afghanistand and Iraq that bridge would have been repaired long ago.

He makes a good point though.  On my most recent trip to China I took the train from Lancaster to Manhattan, then the subway from Penn Station in Manhattan to JFK.  On arriving in Shanghai, I took subways then trains there.  I was struck by how modern and clean the Shanghai subway is compared to New York, and by how clean and fast (>400 km/hr!) the trains were compared to the train from here to NYC.  Granted, the subways and trains here are much older, but all we ever did was put the trains in.  We didn't think about maintenance.  Same for water mains, bridges, tunnels, and streets.  A stitch in time saves nine, as the saying goes.  Now we're in the unenviable position of having to pay for those nine stitches.  Or risk collapse.

[AkSaber]

If we stop bleeding $2 billion a week overseas in Afghanistand and Iraq that bridge would have been repaired long ago.

But... but... cut spending and have responsible finances?!

The Left, nor the Right will tolerate such sorcery.

[Franknburger]

The culprit is most likely the alkali-silica reaction. Within the concrete, calcite hydroxide reacts with silicic acid, forming a silica gel that absorbs water, swells, and ultimately destroys the concrete from within. The reaction occurs if the concrete contains certain materials, especially siliceous limestone, above a certain grain size (smaller grain sizes cause the reaction to take place immediately when the concrete is binding).

Since such limestone varieties are very common along the Western Baltic Sea shore, the reaction was first observed in the 1960s in Northern Germany. The GDR was especially affected, and conducted a lot of research in the 1980s. However, it took until the mid.1990s for that research to be noted in the West, and only some ten years ago international standards for concrete were amended accordingly. [My wife worked for some time in the Lübeck institute for construction material examination, the European competence centre for this reaction - that is how I became aware of its existence.]

We have just have had a similar case in Germany - the Kiel Canal bridge on the A1 motorway, the main transport arteria linking mainland Denmark to the rest of Europe, had to be completely closed for trucks and buses, while passenger car traffic has been restricted to one lane per direction.
http://www.bws.dk/news/news-archieve/2013/august/temporary-extra-charge-due-to-diversion-at-the-kiel-canal.aspx

The problem with the alkali-silica reaction is that it destroys the concrete from inside. You can't detect it during standard inspection and maintenance, the concrete just starts to fall apart without prior warning. As such, I expect this not to be the last of such incidents- to the opposite!  Prepare for putting a lot of money in the infrastructure budget to replace crumbling bridges, especially in areas where siliceous limestone, i.e flint and chert, is common. Apparently, flint occurrences are better documented for Europe than for the USA, but location names such as Flint, MI, Flint Creek, NY, Flint Ridge OH, Flint Creek, AL, Flint River, GA, Flint Hills, KS, or the Flint Creek Range, MT suggest lots of trouble ahead.

On chert, the linked Wikipedia article states

You must be logged in to read this quote.

The Wikipedia geological map below (Legend) provides an overview on surface bedrocks. If this publication from the Iowa Geological Survey (p. 14 f) is representative for the USA as a whole, the darker blue and violet areas are where you can expect more bridges to crumble over the next years.

[Ban my account ffs!]

Excellent analysis and commentary, Franknburger.  Much appreciated.

This was likely a case of an unforeseeable problem.  Still, this just shows that material science is still as valid a field as ever in infrastructure development and underlies the need to continue research while also providing for the maintenance and thorough inspection of our existing infrastructure.

It would be prudent for the federal government to inspect bridges and causeways for degradation of the concrete structure due to these chemical reactions and respond accordingly.

This particular bridge, just like the I-35W bridge in Minneapolis, had seen significant weight stress from construction crews that were resurfacing the bridge deck during or just prior to the failure.  I'd imagine a bridge burdened with slow moving traffic and construction equipment over long periods of time would exploit any design or material failures in the bridge structure.

There is a standard freeway overpass about 3/4 mile from my house that has now twice been struck by drivers who had equipment that exceeded the clearance, causing damage to the understructure.  Both times, the bridge had to be closed immediately.  This time it was struck by a driver who stopped prior to reaching the bridge, had raised some piece of equipment to check on it, and then absentmindedly left it up before proceeding to drive under the bridge.  The first time, the guy had passed under prior bridges without incident... but this particular overpass is slightly lower than the others, though not low enough to warrant any warning (usually they only put a warning up for a clearance under 15 feet... this bridge is 15' 11").

But once the bridge was inspected, they were able to reopen it by redirecting traffic to the opposite side of the bridge, instituting a lower weight limit, and lowering the speed limit while narrowing the lanes, thus keeping weight off of the most damaged part... until they can repair the bridge.

Predictably, large signs were erected within days 1/4 mile before the overpass and on the overpass itself to warn drivers of the slightly smaller than normal clearance. When they resurface the highway underneath in 2016, they are planning to regrade that section to increase the clearance.  As they say... fool me once, shame on you... fool me twice... shame on me.

I bring this up, because it is likely that if we begin thoroughly inspecting our bridges, we'll find that we've been gambling pretty heavily on luck and there will be a tendency for road agencies to begin closing bridges that might just need a few precautions (like not parking heavy construction equipment on them for months at a time).

Unfortunately, it seems we're operating more on the philosophy of "what we don't know can't hurt us"... which 13 people in Minnesota found out the hard way just is not true.