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Should all bridges have height signs?

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  • #32
    niloc1951
    Registered Users, Registered Users 2 Posts: 2,068 ✭✭✭niloc1951


    Davy wrote: »
    Kinda odd but the first bridge southbound on the M7 at the ball has a sign in the median displaying 4.95m about 100 meters before it. Only noticed it on Wednesday, anyone know if it's new?

    Its been there since the early naughties when SDS, now An Post parcel service, put some super cube trailers on the runs out of Dublin from their depot on the Naas Road to Portlaoise and Cork.

    On a wet night while being unloaded rain was cascading down from the roof of one of the trailers onto the loading dock. On inspection it was found the the gutter had been bent flat, it was assumed that while running unloaded a bounce coincided with passing under the bridge in question.

    In the UK bridges with a clearance of less than 16'6" (5.029m) are signed as super cube trailers are in common use there, the EU regulation for international traffic is 4.0m.

    In Europe you will see many tractor units with reduced size rear wheels. This gives two benefits, it reduces the overall hight of the trailer to comply with the 4.0m rule, it also reduces fuel consumption by reducing the frontal area.

    As an aside, would it not be better to plane off a few centimetres from the road surface beneath the bridge in question instead of routing HGV's through the centre of Naas with all the attended negative environmental impact such vehicles bring with them.


  • #33
    [Deleted User]
    Posts: 31,118 ✭✭✭✭ [Deleted User]


    niloc1951 wrote: »
    As an aside, would it not be better to plane off a few centimetres from the road surface beneath the bridge in question instead of routing HGV's through the centre of Naas with all the attended negative environmental impact such vehicles bring with them.

    Probably better to jack up the bridges, otherwise motorway traffic would experience a "yump" as the vehicle drops and rises again, either that or plane several hundred metres and relay to avoid a sudden change in height.


  • #34
    niloc1951
    Registered Users, Registered Users 2 Posts: 2,068 ✭✭✭niloc1951


    Deleted User wrote: »
    Probably better to jack up the bridges, otherwise motorway traffic would experience a "yump" as the vehicle drops and rises again, either that or plane several hundred metres and relay to avoid a sudden change in height.

    Can't resist :D:D

    'yump' originated from Scandinavian rally drivers way back in the '60's to describe their airborne travel after driving extremely fast over a sudden but short elevation in the road which caused the car to 'jump' off the road. A real expert in the art could travel over five car lengths before touchdown.

    Couldn't really see a 44t artic doing this ;).

    Seriously though, the phenomenon you describe is not at all uncommon on your primary route network, there is a particularly good one which can give the stomach a real sinking feeling on the westbound side of the N25 west of the Cobh slip.


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