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Bridge rating markings on vehicles


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I know that by 1909 it was the responsibility of a general staff officer at the approach to a bridge to give instructions to commanders of units about the suitability of the crossing. By 1911 the responsibility of giving the bridge a load classification passed to the engineers in the unit constructing the bridge. They were required to indicate at each end of the bridge the greatest permissible load but this was not yet numerical.

By 1939 all bridges where classed according to the maximum weight of a vehicle in tons giving the following Classes 5, 9, 12, 18 or 24. Bridge classes applied not just to fixed bridges but to pontoon bridges as well.

So if bridges were classed by 1939, presumably vehicles were marked up accordingly?

 

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5 hours ago, fv1609 said:

I know that by 1909 it was the responsibility of a general staff officer at the approach to a bridge to give instructions to commanders of units about the suitability of the crossing. By 1911 the responsibility of giving the bridge a load classification passed to the engineers in the unit constructing the bridge. They were required to indicate at each end of the bridge the greatest permissible load but this was not yet numerical.

By 1939 all bridges where classed according to the maximum weight of a vehicle in tons giving the following Classes 5, 9, 12, 18 or 24. Bridge classes applied not just to fixed bridges but to pontoon bridges as well.

So if bridges were classed by 1939, presumably vehicles were marked up accordingly?

 

 

I seem to recall there was a publication for working out what the bridge could carry, not sure who was responsible for checking, may have it some where, if it was electronic its the kind of thing I would down load

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There was and will be.  The Royal Engineers Pocket Book.  RSME always included an exercise in doing precisely that on the various combat engineer courses.  You would have to do it for a selection of bridges and it involved various measurements and calculations.  Interestingly, some of the strongest are the oldest - I recall one stone bridge dating from medieval times working out at about Class 120 and even then, its only limiting factor was its width!  But, to modern engineers this was shocking of course - building a bridge to carry a horse and cart which was so clearly over-designed!

Perhaps some forum members will remember their days in BAOR where every bridge, culvert and sharp bend was faithfully recorded on "Road and Bridge" maps held by RE, RMP, RCT and so on to enable easy planning of convoy routes.  Such obstacles were themselves marked with bridge circles showing limits for both single and double traffic. By and large, most vehicles, apart from heavy armour, could cope with most public roads, but I do recall that the 35-tonne Crusaders and the Coles MkV cranes were restricted - the latter due to its height - just over the standard 4m - the general minimum clearance for bridges on German roads.  

 

10 68

 

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The fitting of bridge plates to vehicles predates the out break of the second world war you can find photos of vehicles in the uk in 1939 with them fitted  but if you look at vehicles with the BEF in France in the run  up to DUNKIRK you will find little evidence of them in photo taken at the time also on any Pathe news reels shot in Belgium or France

 

 

 

 

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  • 1 month later...

The RAF circulated a letter, "Yellow Discs on Vehicles", which I have yet to see (I hope it's in TNA somewhere), but I have references to it. It was dated 3/9/1939.

Edited by RAFMT
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It took a while for them to be applied to vehicles that weren't likely to leave to the airfield however. Things like tractors and such, you see photographs well into the war showing tractors without bridge markings.

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