Bridge signs were usually a 9" yellow disc with black numbering. Sometimes a black disc was used with the number outlined in yellow. The correct shade of yellow is 356 (previously No56) Golden Yellow from BS381-C.
Examples of signs, the first has a weight classification of 5 tons the second is for a towing vehicle of 18 tons with a combined load of 50 tons.
As with all Army regulations, rules were not always followed and lists were often revised.
The following list was published in 1943.