TX: Bridge Under Const; beam collapses onto traffic on I-35 in Salado

[Brian556]

http://www.kwtx.com/home/headlines/Major-Crash-On-Interstate-35-Shuts-Down-Highway-297669591.html

Initial reports say a truck hit the bridge, causing the collapse. However, evidence suggests that this could have been a construction accident/defect.
It looks like the England truck is not the cause of the collapse. There is a flatbed on the other side involved, but I can't tell if he had a load that came off upon impact or not. It looks like this could have been a construction defect. Notice that the end of the cap ( the top portion of bridge support) is sheared off. I'm wondering if was defective or not fully cured before the beam was placed on it.

[kkt]

One dead, but he was a car driver.  So the truck drivers should live to testify, hopefully.

[rantanamo]

TxDOT says truck that was too tall went under and struck a beam

[longhorn]

Traffic being rerouted through Killeen, up 195.

http://kdhnews.com/military/with-i--traffic-routed-through-killeen-fort-hood-releases/article_091291dc-d3f8-11e4-acd6-dfcb5f1dc0b0.html

[Scott5114]

Wait, if this was a new bridge being constructed over an Interstate, why was it low enough for an overheight vehicle to strike it? It should have been built to Interstate standard, meaning almost any truck driver should have been able to pass under it.

[Brian556]

Quote from Scott 114:

Wait, if this was a new bridge being constructed over an Interstate, why was it low enough for an overheight vehicle to strike it? It should have been built to Interstate standard, meaning almost any truck driver should have been able to pass under it.

That was my thought when I saw the pics. What I saw did not add up. The England truck is a standard-height truck, and therefore could not have struck the bridge due to clearance issues. There was a flatbed involved going the other way, but I could not tell if there had been something on his trailer that might have hit the bridge and come off. However, that truck wasn't necessarily in the ideal position to have caused this.

This incident is very interesting from an engineering perspective.

Everybody is saying that a truck hit the bridge somehow.

So, I see 3 possibilities.

1. The flatbed going the other way plowed through the concrete barrier walls and struck the center support, breaking the end of the cap, and causing the beam to fall.

2. Some truck hit it in a clearance accident. The flatbed appears to have had no load, so I dunno how he could've did it. If the top of hit tractor hit it, it should have given way enough not to break the beam. I found some new video, showing  a "TRUCKS USE RIGHT LANE" sign at the scene, and the flatbed is in the left lane, so that leads me to lean more towards a clearance accident.

3. The cap failed due to faulty construction, or not being fully cured, causing the beam to fall.

I've never seen a beam fall like that before. I'm thinking it was more vulnerable to falling because it did not have the decking holding the bridge together.

Even if this were a clearance accident, that beam is incredibly heavy and strong, and you would not expect it to fail, even if struck by a high load.

[wxfree]

Wait, if this was a new bridge being constructed over an Interstate, why was it low enough for an overheight vehicle to strike it? It should have been built to Interstate standard, meaning almost any truck driver should have been able to pass under it.

The bridge was slightly over 14 feet above the roadway, and was signed with a 13.5 foot clearance, to leave a margin.  The bridge is new, but the photos seem to show the road to be under construction.  Presumably the plan is to build the final pavement at a lower elevation and increase the clearance that way.

http://www.statesman.com/news/news/crime-law/bell-county-reported-bridge-collapse-on-interstate/nkfxd/

Edit: The posted height I gave was based on the text of the story, but in the photo gallery it clearly shows a posted clearance of 14 feet 3 inches on the front of the bridge.

[dfwmapper]

Right, it's still the old pavement there. They built the half of the bridge that would carry the new westbound lanes for FM 2484 just north of the old bridge, demoed the old bridge, and are building the other half of the bridge for the eastbound lanes in its place, and that was what was hit. Once the new bridge is fully constructed, they will pave the new northbound lanes of I-35 under it, shift all 4 lanes onto that pavement, then rip out all the old stuff, regrade it, and pave the new southbound lanes, which will end up much lower down than the original lanes in order to increase it to the minimum 16.5' clearance TxDOT requires. Same strategy has been used all along there in order to get enough room for 6 lanes (current) and 8 lanes (future).

[kphoger]

The official report states that an oversized truck struck the facility, not a standard-height truck.

[longhorn]

Right, it's still the old pavement there. They built the half of the bridge that would carry the new westbound lanes for FM 2484 just north of the old bridge, demoed the old bridge, and are building the other half of the bridge for the eastbound lanes in its place, and that was what was hit. Once the new bridge is fully constructed, they will pave the new northbound lanes of I-35 under it, shift all 4 lanes onto that pavement, then rip out all the old stuff, regrade it, and pave the new southbound lanes, which will end up much lower down than the original lanes in order to increase it to the minimum 16.5' clearance TxDOT requires. Same strategy has been used all along there in order to get enough room for 6 lanes (current) and 8 lanes (future).

Reassuring to know that this rebuild of I-35 is going to make the expansion to four lanes easier in the future. It will be needed soon. I just trying not imagine the horror of going through the remake of the Temple section.

The increase in truck traffic was significant on 195, and Killeen Police were at the major intesections electronically overriding the light sequence to keep the traffic moving.

The only thing that was horrible was the communication via the electronic signs. My35.org showed the signs near the closure for people to go the my35.org website for more info.........Hellooooooooooo Txdot, people are driving.

[Brian556]

Quote from Longhorn:

The increase in truck traffic was significant on 195, and Killeen Police were at the major intersections electronically overriding the light sequence to keep the traffic moving.

Huh? the police were actually making an effort to keep traffic moving? Usually they just block off the accident scene, and don't make any effort on traffic flow. They often make things worse than necessary by blocking off more than they need to.

Flower Mound is the worst about this. They don't give a fudge how much of a backup they cause. Once they were detouring traffic off a major road onto a side street. but did not post an officer to direct traffic at the next intersection, which had no signal, and nobody could get out from the stop sign. Of course, there were several officers standing around the accident scene doing nothing.

Denton and Denton Co do better.

[Scott5114]

Right, it's still the old pavement there. They built the half of the bridge that would carry the new westbound lanes for FM 2484 just north of the old bridge, demoed the old bridge, and are building the other half of the bridge for the eastbound lanes in its place, and that was what was hit. Once the new bridge is fully constructed, they will pave the new northbound lanes of I-35 under it, shift all 4 lanes onto that pavement, then rip out all the old stuff, regrade it, and pave the new southbound lanes, which will end up much lower down than the original lanes in order to increase it to the minimum 16.5' clearance TxDOT requires. Same strategy has been used all along there in order to get enough room for 6 lanes (current) and 8 lanes (future).

That seems like a weird way of doing it. Why not just make the bridge 3 ft higher?

[seicer]

Could be because of cost. Like most Texas interstates, there are adjacent frontage roads that would need to be raised.

--

In one of the articles, the company the truck driver represented was lashing out at TxDOT. But by all indications, it seems that the truck driver ignored or missed the height requirement signs for his oversized truck.

[dfwmapper]

That seems like a weird way of doing it. Why not just make the bridge 3 ft higher?

Pretty much impossible to do without a long term closure of the crossroad and frontage roads. The way they're building things now, almost all of the crossroads have been maintained with minimal closures (just overnights/weekends for paving and traffic shifts). They're not going to close off access to a state highway for a year if they can possibly avoid it.

[codyg1985]

2. Some truck hit it in a clearance accident. The flatbed appears to have had no load, so I dunno how he could've did it. If the top of hit tractor hit it, it should have given way enough not to break the beam. I found some new video, showing  a "TRUCKS USE RIGHT LANE" sign at the scene, and the flatbed is in the left lane, so that leads me to lean more towards a clearance accident.

I would think that if the truck using the wrong lane would cause a normal-height truck to strike the beam, then more signage than "TRUCKS USE RIGHT LANE" would have bee in place. In a lot of cases, I have seen trucks not pay attention to these signs, especially if it instructs trucks to use the left lane.

[dfwmapper]

The 'trucks use right lane' signage is in place for horizontal clearance, not vertical. There's basically zero left shoulder there due to the barrier, while there is a bit on the right. There are some relatively sharp curves as the lanes snake back and forth between the old and new pavement, so better to give the trucks a little extra room and not have them try to be passing each other through the narrow sections.