The minimum requirements, if not the exact specification, of the pit into which a chassis dynamometer is to be installed will invariably be provided by the dynamome- ter’s manufacturer which will include the loading on the pit floor to aid the structural designer. The pit must be built to a standard of accuracy rather higher than is usual in some civil engineering practice since all pit installed dynamometers have a close dimensional relationship with the building in which they are installed; this is par- ticularly true for the pit construction which has to meet three critical dimensional standards: