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Lorry crashes into and demolishes pedestrian bridge.

Lorry crashes into and demolishes pedestrian bridge.

RE: Lorry crashes into and demolishes pedestrian bridge.

Unlikely that a designer can forsee all the stupid things people do when hauling equipment. Fortunately most roadway bridges have enough mass that complete failure does not happen. For example take this OG. I had a bicycle attached to the top of my car and went under a very low rail road bridge well marked to keep trucks out. The bike escaped with maybe with maybe 1 mm of clearance.

RE: Lorry crashes into and demolishes pedestrian bridge.

Interesting that the excavator doesn't even look blemished after the event. It makes that bridge look a little tooo weak to me.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Lorry crashes into and demolishes pedestrian bridge.

Maybe not. Seems 60MPH excavators pack some serious kinetic energy.







Keith Cress
kcress - http://www.flaminsystems.com

RE: Lorry crashes into and demolishes pedestrian bridge.

Enough energy to put the draggin' wagon frame on the ground too...

Mike McCann, PE, SE (WA)


RE: Lorry crashes into and demolishes pedestrian bridge.

(OP)
I see , if an excavator can do that to a vehicle bridge, a pedestrian bridge does not stand a chance.
B.E.

You are judged not by what you know, but by what you can do.

RE: Lorry crashes into and demolishes pedestrian bridge.

Maybe it takes some sort of extra fee for hauling back-hoes, more or less insurance for fixing their damages caused.

RE: Lorry crashes into and demolishes pedestrian bridge.

Interesting that the article says people were stuck on the highway for 6 hours. Did the concept of backing up to the last exit not occur to anyone?

RE: Lorry crashes into and demolishes pedestrian bridge.

Have you ever tried to get 3 or 4 lanes of traffic to ALL back-up to the last exit?

Actually Texas is one of the few places where they've addressed this issue directly. Virtually every mile of freeway has what they call 'service roads' on each side of the interstate and there are no fences or barriers along the side of the highway so it's easy to just drive off the shoulder and onto the service road. In fact, my son, who's lived in Texas for something over 16 years, jokes that when you see obvious tracks in the grass down onto the service road, he says they call that a "Texas Off-ramp".

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Lorry crashes into and demolishes pedestrian bridge.

John, That is actually logical, which is why we can't do that here. The lack of roads means in some places 30 mile detours. Besides that it would mean the state would have to spend money in places outside the state capital city.

And how about the concept of turning around to go back to the last exit.

But maybe if you are a trucker, and are required to only use the main highways, then there maybe no other option. Pull over and sleep it off.

I'm sure the rules are different there, and someone had a reason for the design they have.

RE: Lorry crashes into and demolishes pedestrian bridge.

This looks like a new, quicker method to demolish a highway bridge.

Mike McCann, PE, SE (WA)


RE: Lorry crashes into and demolishes pedestrian bridge.

I remember when I was young, there was a particular underpass up in the Houston area where a highway went under a railroad, with something like a 13' clearance (IE, lower than normal). That underpass was finally taken out by a trackhoe in similar fashion to those above. Get one of those things moving fast, and you've got an unstoppable-force-meets-immovable-object situation.

RE: Lorry crashes into and demolishes pedestrian bridge.

Reversing on the motorway is thoroughly frowned-upon here.

The two junctions nearest to me are ten miles apart - which is well short of the longest stretch in the UK, but still a long way to be be going "wrong way" down a major road without being really sure that you aren't going to encounter someone coming the other way at 80+ mph.

Then there's the difficulty of getting articulated vehicles off the motorway at the junction (the entry angles aren't nice and the roundabout needs to keep running the right way to cater for traffic arriving from the other direction).

With all that in mind, current strategies seek to minimise closure duration first, provide in-situ welfare for stranded travellers if that isn't possible and evacuate them from their vehicles as a last resort.

A.

RE: Lorry crashes into and demolishes pedestrian bridge.

I know that this is a bit off-topic, however, since we've been looking at a lot of pictures of excavators and other large yellow pieces of equipment, and I further suspect that many of us, when we were kids, may have had 'sand box' toys modeled after stuff like this. And so I thought it might be of interest to learn that there's a place outside of Las Vegas, NV where you can go and 'play' with the real thing:

http://digthisvegas.com/

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: Lorry crashes into and demolishes pedestrian bridge.

There is something odd about this.

The lorry with the low loader was apparently going slowly along the hard shoulder.

It has clearly passed under the gantry sign just before it.

The footbridge is a curious design with a narrowing section to allow a slope on the bridge while keeping the bottom flat and set height above the carriageway.

It would seem that the bridge section just rested on the pillar and on the midway joint.





In terms of backing up that is what happens normally. However, the location here was odd. The London bound carriageway was not far from a junction and was cleared. The southbound carriageway - the one with the bridge still standing is just beyond a complex motorway junction which made it very difficult to reverse traffic.

In the end they decided that the bridge left standing was secure and allowed traffic under it.

Motorway was closed for a day and a half.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Lorry crashes into and demolishes pedestrian bridge.

Difficult to judge from any photo I've seen and especially when you look at vertical distance above the edge of the hard shoulder, not the extreme end.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Lorry crashes into and demolishes pedestrian bridge.

OK,

Some more digging (excuse the pun) finds a bit more evidence.

This pic is the best I've seen and given that the low loader is currently crushed under the weight of the bridge so probably 0.5m lower than it would have been and an eye witness report who heard a "loud bang", it looks like the digger arm hit the side of the bridge hard enough to hit it sideways off its support on the outside of the carriageway.

Now whether the bridge was as high as it should have been or the digger was over the maximum height is going to be the key question.



I think the timing of it, the fact it hit the lorry first and the now near universal application of anti-lock brakes saved us from a multi vehicle pile up. That and the bike rider who just managed to slide under the bridge as it collapsed.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Lorry crashes into and demolishes pedestrian bridge.

Quote (JohnRBaker)

I know that this is a bit off-topic, however, since we've been looking at a lot of pictures of excavators and other large yellow pieces of equipment, and I further suspect that many of us, when we were kids, may have had 'sand box' toys modeled after stuff like this. And so I thought it might be of interest to learn that there's a place outside of Las Vegas, NV where you can go and 'play' with the real thing:

http://digthisvegas.com/

I've been there, it's an absolute blast. Worth every penny.

RE: Lorry crashes into and demolishes pedestrian bridge.

IR stuff,

That's a good view, but exaggerates it a bit as the edge of the hard shoulder is the key bit as the bridge is definitely on a slope down. The modern bridges and gantries are apparently 5.5-5.7m, but the bridges only need to be 5.03 (16 ft 6") though whether that applied to the hard shoulder when they built the motorway is not clear.

either way its quite a bit less than the gantry.

Interestingly the HSE website quotes 5.1m (!) and the new super tall trailers are up to 4.9m. Definitely scary seeing those go under some of the bridges.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Lorry crashes into and demolishes pedestrian bridge.

On a trip around Chicago and heading west on the Tri-state I came to stalled traffic. Decided to take my 4 x 4 Chevy Suborban down trough the median and up to the east bound lane. Luckily had the machine in 4 wheel drive and flooring accelerator pedal causing maximum RPM and with wife screaming, throwing mud all over creation I made it out. Could have been siting there a day and a heavy fine Next trip through that area I noted they decided against any such move and a median fence had been erected instead. Left at next exit and ate lunch there. Upon leaving restaurant, see the backup was not moving, so I took a parallel road home. One reason why now I use the old road instead of Interstate if no hurry and I have a more pleasant no traffic situation. At at age 88 I don't need any more such experiences or stalled traffic frustrations.

RE: Lorry crashes into and demolishes pedestrian bridge.

(OP)
One thing that intrigued me was that the impact with the bridge did not displace the digger off the back of the flat bed.
B.E.

You are judged not by what you know, but by what you can do.

RE: Lorry crashes into and demolishes pedestrian bridge.

That digger is pretty heavy, at least 18600 kg. More importantly, the boom's design is such that the impact force is directed downwards, because of the curve in the boom. So, the force of the impact is actually magnified because, it's pushing downward on the truck, which won't give as much as it might have if the force were directed rearward against the digger. If you look at the curve of the main boom, it's as if it were designed specifically to redirect the impact force downward. More amazingly is the fact that the joint on the boom appears to be completely undamaged. Of course, this might have all been augmented by the lack of lateral resistance of the walkway. Kudos to Hitachi for building a supremely robust digger!

TTFN (ta ta for now)
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RE: Lorry crashes into and demolishes pedestrian bridge.

Sorry for bumping an old thread but don't come here often and for some reason the title of this one got my attention.

Anyway, looking at the pictures of the pedestrian bridge, is it my imagination or does it not have much (any?) visible rebar where the break is?

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RE: Lorry crashes into and demolishes pedestrian bridge.

No its not your imagination. The design of this particular bridge is a bit odd and the section that feel off was basically a simply supported beam resting on two supports. The far side of the bridge is a much more solid cantilever....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Lorry crashes into and demolishes pedestrian bridge.

Two separate pre-cast sections lifted into place, held there by gravity and the grace of God. And maybe a little engineering judgement that didn't foresee forty-odd tonnes hitting it at 56mph...

RE: Lorry crashes into and demolishes pedestrian bridge.

Apparently the lorry hitting it was crawling along the hard shoulder so 5.6 mph would be closer. ... Does seem remarkable that it was essentially gravity holding it all together for the last 25 yeasts.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Lorry crashes into and demolishes pedestrian bridge.

Not too odd. "Cantilever" style bridge construction with a "suspended span". Fairly efficient, and very constructable.

Although I'm most used to seeing it for large steel trusses over waterways -- lower collision risk there!

RE: Lorry crashes into and demolishes pedestrian bridge.

Missed that, thanks LittleInch.

RE: Lorry crashes into and demolishes pedestrian bridge.

Lomarandill,

To me, though I'm far from an expert, the odd thing is that there is one long cantilever over about half the span / motorway, then this beam between the end of the cantilever and what is basically a pin support. If you look back at the google streetview images I posted on 30/8 at 0843, you can fairly clearly see the beam section ends. The first half cantilever stood the test and was suspended over the motorway until it was demolished a few day later.

The design is also strange as the bridge deck is clearly on a slope down from one side to another but also narrows down as it gets to the far side.

I think someone went a bit too far trying to save on concrete and the height of stairs on the far side. This is a pedestrian bridge which then has a circular walkway on the side it was hit.

If anyone had actually been on it when it was hit it's fairly clear they would have died. how no one else was seriously injured is a minor miracle which might not happen next time.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Lorry crashes into and demolishes pedestrian bridge.

Quote (LittleInch)

there is one long cantilever over about half the span / motorway, then this beam between the end of the cantilever and what is basically a pin support

LittleInch, what you describe is pretty much the framing, using what appears to be cast-in-place section with dapped end (on the left), then the a precast drop-in (maybe should be retitled 'drop-down' surprised), with the far right end of the precast supported in a simple seat over the pier, as per below tagged photo:




The dapped end of the precast segment, in detail:



The far right support end over the pier:



This is somewhat common framing, using precast segments, and cast-in place too. Evidently, the lateral capacity of the simple seats is questionable.

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