This Advice Note sets out procedures and denotes materials which will provide the best possible performance of road chamber top and gully top installations in trunk roads and motorways. Its recommendations may be applied to other roads and traffic conditions, as appropriate.
Key points from the document:
Increased flange dimensions reduces load on bedding area which must not exceed 2.1 N/mm2
Flange width to be 50-120mm and must be at least 5mm in thickness
Gussets should conform to BS7903. Gussets must be below the top of the frame by 25mm or more
Recommends 150mm deep frame for manhole covers installed in trunk roads and motorways
Any frames weighing more than 15kg must have provisions to allow balanced lifting
Frame features allow a high level of mortar engagement