Bridge collapse on M20

[bobbo89]

don'tbesilly said:

I get where you and FunkyChucker are coming from, but that point does seem to be where the two halves have parted company,admittedly it could have been as a result of an impact, and not necessarily at that point.

That is the point at which they've separated, essentially the impact has just nudged a section off its perch

[Elysium]

Just noticed the hatching on the hard shoulder here.

I think the bridge is lower in this section and if you look at the overhead shots the flat bed with the excavator is on the hard shoulder not the main carriageway.

Combination of:

1. Excavator not properly loaded
2. Truck runs down hard shoulder where bridge is below 5.3m
3. Bridge is weak in design. Forward impact nudges the central section forward.
4. Bridge separates at movement joint and collapses.

Edited by Elysium on Saturday 27th August 15:27

[bobbo89]

Wrong side that but i'd imagine there'd be hatchings on the other side too

[Elysium]

bobbo89 said:

Wrong side that but i'd imagine there'd be hatchings on the other side too

You are right. No hatching on the other side, but the bridge is definitely lower on the hard shoulder:

https://www.google.co.uk/maps/@51.3088291,0.380234...

Driver will be in trouble.

Looking at the other direction, the hatching is there to keep traffice away from the bridge support structure, which quite close to the carriageway. Quite a fall on the bridge in comparison to the gantry behind it:

https://www.google.co.uk/maps/@51.3088127,0.37923,...

Edited by Elysium on Saturday 27th August 15:34

[Bristol spark]

Is the M20 a smart motorway, with the hard shoulder a live lane?

The digger still looks too low to hit bridge in that pic? And cannot of been hardly moving to stop so close to the bridge with so little damage.

[bobbo89]

The bottom section of the bridge is perfectly level with the upper section being sloped to give it its elevation. Creates a bit of an illusion of it being sloped when actually the base of it is bang on level.

edit: at least I think so anyway....

[cahami]

Recovery firm transporting the digger

[CAPP0]

Bristol spark said:

Is the M20 a smart motorway, with the hard shoulder a live lane?

The digger still looks too low to hit bridge in that pic? And cannot of been hardly moving to stop so close to the bridge with so little damage.

No it's not smart at that point. This is a mile or so from where I live, I use the M20 every day. That bridge has a very significant slope on it from north to south, but I'm not sure whether t's lower at the south end, i.e. the footpath slopes but the bridge may be the same height all the way across the m/way. Eye-witnesses are categoric that the digger arm took it down. Still can't work out how the truck carrying it got that far without whacking something else, but I note earlier comments about the shelf being hatched out there - haven't noticed that myself.

The surrounding roads are carnage. I had to go out so used the bike but there's little or no point trying to take a car anywhere at present, and they say probably shut until tomorrow at least. They'll have to take to other half of the bridge out, it's hanging out in some sort of cantilevered manner at present.

Haven't read the whole thread but apparently the only casualty is a biker who had to bin the bike and slid under the gap left under the bridge! You can see him being worked on in some pics and thus work out how he got there. Broken ribs but not life threatening. Wonder how many of us would have had that presence of mind, the alternative would have been head on into the bridge and presumably instant game over

I (used to!) cycle over that bridge!

Edited by CAPP0 on Saturday 27th August 15:54

[PRTVR]

I remember talking to a low loader driver as I helped him load up a large digger, I was surprised at the lack of mounting points on the machine, basically he was wrapping chains around the tracks to secure it, he said it would be fine, the worst thing is when the arm extends by itself and hits a bridge,
I thought he was winding me up, he went on to say if you don't believe me look at most bridges as you pass under them, there will be lots with dents in them (Metal type) and he was right.

[CAPP0]

Brigand said:

There have been bridge works taking place on the bridge just past jct4 (London bound) for a few months now. It may well have been one of those that collapsed, although I think the works are focussed on a main road bridge rather than a pedestrian one.

Nothing to do with that, that's J4, mile or two away.

[carlpea]

Looking at the pictures I reckon that second truck, along with their quick reactions, saved the biker's life.

[cahami]

Maybe the driver on the hard shoulder had just started to pull away, it seems unlikely he was doing any sort of speed due to the lack of damage to the digger arm

[Bristol spark]

Well google kind of confirms its slightly caotic!! Looks like an accident slightly up as well!

Dont think ive ever seen so much "red"

[dandarez]

Why no central support? Would it have collapsed the same with a central?

Ok, it's narrow, and pedestrian useage only which begs the question then why the need for substantial concrete structure? Why not steel like the main road signage/speed bridge on that side just prior to the collapsed bridge?

But what do I know? Nothing of course.

Just a concerned view of a PH who regularly drives under these damn things!

[dandarez]

Bristol spark said:

Well google kind of confirms its slightly caotic!! Looks like an accident slightly up as well!

Dont think ive ever seen so much "red"

[pic]http://i210.photobucket.com/albums/bb89/matt_webb/9733AEBC-8B8A-4577-B097-1B184516EBB7.png[\puc]

My daughter's family were going that way today (off to Disneyland) but got wind of the main accident (and the additional ones!) in time to divert M23 to get to Ashford.

Thoughts have to be with the biker.

[Elysium]

bobbo89 said:

The bottom section of the bridge is perfectly level with the upper section being sloped to give it its elevation. Creates a bit of an illusion of it being sloped when actually the base of it is bang on level.

edit: at least I think so anyway....

It is difficult to tell for certain from the street view image, but if you compare it to the gantry behind there is definitely a slope to the structure.

Also look at the shadows on the satellite view:

https://www.google.co.uk/maps/place/M20,+Maidstone...

The gantries shadow is parallel, but the bridges shadow is angled due to the slope.

[carlpea]

This part of the bridge is too cleanly cut to be 'torn' so I reckon that part of the bridge was just pushed off where it floats on its expansion joints.



Edit: Yep, definitely an expansion joint either side of the part that 'fell off'.

Edited by carlpea on Saturday 27th August 16:18

[bobbo89]

Elysium said:

It is difficult to tell for certain from the street view image, but if you compare it to the gantry behind there is definitely a slope to the structure.

Also look at the shadows on the satellite view:

https://www.google.co.uk/maps/place/M20,+Maidstone...

The gantries shadow is parallel, but the bridges shadow is angled due to the slope.

Yep, seeing that I think your right and I'm wrong, started to doubt myself after I posted, hence the edit.

[dandarez]

Elysium said:

bobbo89 said:

The bottom section of the bridge is perfectly level with the upper section being sloped to give it its elevation. Creates a bit of an illusion of it being sloped when actually the base of it is bang on level.

edit: at least I think so anyway....

It is difficult to tell for certain from the street view image, but if you compare it to the gantry behind there is definitely a slope to the structure.

Also look at the shadows on the satellite view:

https://www.google.co.uk/maps/place/M20,+Maidstone...

The gantries shadow is parallel, but the bridges shadow is angled due to the slope.

Interesting. The sloping shadow is on the other carriageway, but I see exactly what you mean.

Still puzzled why the need for a concrete structure for narrow pedestrian use, and why no central support?

[CAPP0]

bobbo89 said:

Elysium said:

It is difficult to tell for certain from the street view image, but if you compare it to the gantry behind there is definitely a slope to the structure.

Also look at the shadows on the satellite view:

https://www.google.co.uk/maps/place/M20,+Maidstone...

The gantries shadow is parallel, but the bridges shadow is angled due to the slope.

Yep, seeing that I think your right and I'm wrong, started to doubt myself after I posted, hence the edit.

Here's the "before" shot. As I said above, the path on the bridge has quite a fair gradient on it. There's a bit of an optical illusion going on, the underside of the bridge slopes less so, but it does look low at the (alleged) point of impact, if the truck with the digger was travelling on the shelf for any reason.