Results of investigations at scenes of motorway accidents in which safety fences have received severe impacts have shown that where concrete is used for post footings, the footings are not always made to the correct standard. The british department of transport specification calls for the footing to be 350 mm diameter (or 310 mm square) by 950 mm deep; footings are frequently twice the correct diameter and half the required depth. The use of performed cylinders has been studied, in field trials, as a means of controlling the formation of the footings. A satisfactory performance has been achieved using a prefabricated cylinder to the correct dimensions in very poor ground conditions, where concrete footings would normally be specified. (A) This is paper 3 of the TRRL papers presented to the 1986 TRB annual meeting.
Samenvatting