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M20 lorry accident sparks guidance concerns

Kent Fire and Rescue

A lorry strike on an M20 pedestrian bridge over the Bank Holiday weekend has raised concerns around network management.

A digger being transported on a lorry travelling towards London struck the pedestrian bridge on Saturday 27 August at 12.05pm resulting in a partial collapse.

No-one was seriously injured in the accident, although a motorcyclist suffered broken ribs in throwing himself off his bike to avoid hitting the collapsing bridge deck. Part of the bridge also fell on to a second lorry, the driver of which was treated for shock at the scene.

The motorway was then closed in both directions between junctions 1 and 4, causing traffic chaos.

Kent Police’s Serious Collision Investigation Unit are conducting an investigation into the accident and the RAC Foundation has led calls for Highways England to do more to ensure lorry drivers are aware of the risk of bridge strikes.

“The M20 crash raises many questions, chief amongst them: is enough being done to ensure lorry drivers understand the limitations of the network?” said a spokesman.

“Guidance on the Highways England website refers extensively to the weight, width and length of abnormal loads but there is less said about height considerations which is arguably the bigger area of concern,” he added.

The RAC said that Highways England should look to emulate Network Rail which takes the risks far more seriously.

“Network Rail closely records the 1,500 or so annual vehicle strikes on bridges which carry its tracks but is there such a systematic approach to what happens elsewhere on the transport network?” it asked.

The RAC added that the M20 incident was not a new phenomenon. Two years ago a Department for Transport report recognised that: ”Structures such as footbridges or pipe gantries are particularly vulnerable where drivers are careless about the height of their loads and, as a result of such carelessness; several have been dislodged or brought down over the years across the country.”

Highways England declined to comment on the cause of the accident, citing the ongoing Police investigation.

Highways England contractors removed the collapsed span on Sunday and the remaining elevated structure was inspected and declared safe before the motorway was reopened. An operation to remove it will begin in the coming weeks.

Engineers said that the fault appeared to lie with the lorry driver. Bridges on the motorway network have a minimum clearance of 5.7m, according to Highways England. This expands across the carriageway to include the hard shoulder.

”The M20 footbridge was sloping quite heavily - so, the lowest point is definitely at the location where it was indeed struck. I’d be more than reasonably sure that the culprit was the low-loader/digger being too high, rather than the bridge being too low,” independent bridge designer Simon Bourne told New Civil Engineer.

M20 bridge strike

M20 bridge strike

Source: NPAS Red Hill

There were suggestions that work may have been ongoing on the bridge. A Varley and Gulliver branded Combisafe system was in place when the collision took place.

But Varley and Gulliver confirmed to New Civil Engineer that it was not working on the bridge when the collision took place, and that the product – after an initial lease period – was sold at least a year and half ago to the then contractor on the road.

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Readers' comments (5)

  • Philip Alexander

    It's obvious to me that the offending truck was actually on the hard shoulder when its digger struck the suspended span which then fell off. The positioning of the trucks show that quite clearly in that they had both travelled less than a few metres from the centreline of the pedestrian bridge after the span fell off. So the two big questions are why was the low loader plus digger actually travelling on the hard shoulder at speed and since it was, why did it strike the bridge? If it had been moving slowly along the hard shoulder then it's unlikely that the span would have been knocked off; and if its height was within the 5.7m loading gauge then the bridge must have been too low at that critical point at the back of the hard shoulder due to its steep gradient across the motorway. I'd be surprised if all overbridges gave a 5.7m clearance since that's a fairly recent standard and this is an old bit of motorway. The other evidence available which suggests this particular bridge was too low at that critical point was the proximity of both the sign gantry and another overbridge just 'upstream' of the pedestrian bridge both of which the low loader would have travelled beneath before it struck the footbridge. All in all, a clear pointer for proper asset management so that HE should know where all its pinchpoints are.

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  • The lack of redundancy of half jointed structures was also a factor

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  • Shame there no "Like" button to both of the above.
    To an outsider the span that fell looks remarkably "simply supported" before it was "Bashed" with a great deal of KE....( from a very well aimed metal jousting horse ! )
    And the remaining cantilever which probably now alarms the wits out of ordinary motorists passing under it, is now presumably quite lightly loaded , and looks by far the more robust structure in the first place !

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  • Agree with all above. Due to their design these 70's/80's pedestrian bridges have served landowners, walkers etc well with their ability to traverse from one ground level to another, many without steps. However HE to check assets and act if 5.7m height is breached . If they cannot come up with some form of electronic "goal post" and subsequent illluminated stop sign then sections of hard shoulder will have to be closed.
    On this incident, I welcome P Flannery Plant Hire (Oval ) Ltd's web site notice concerning the transport responsibility for their wheeled 360 excavator and dumper. Transport of this size of construction plant is for experienced low loader companies only with card operating plant operators.
    You can find the specification for the Hitachi excavator on their web site. You will notice the length on a low loader required to keep the jib sections below the cab height.
    On the scene, there could have been a fatality, the white DAF wagon taking part of the load of the dislodged span. The excavator bucket looked attached but for front loading which prevented dipper arm being lowered more ?
    Driving in the hard shoulder suggests unable to drive at min 50 mph ?
    14 T / 17T excavator should have been in middle of low loader?
    These are all questions for the police, I am no expert in this field.
    On a passing note please, please, please no more references to "diggers", "cement wagons", rather tracked /wheeled excavators and concrete wagons.
    Lets do all we can to help the public understand us more.
    Brian Close

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  • Philip Alexander

    Would it be too much to ask the NCE to do follow-up articles on topics like this? We're all intensely interested in these types of incidents but we never find out exactly what the cause was. Can you please provide some proper journalism to provide the next story, which actually might be far more interesting and far reaching than the original drama. What if HE had to replace a 100 bridges at a cost of say £2-3million each over live motorways? That might knock a hole in their budget. And now they might know there are problems they have to do something about it. thanks

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