Until the early 1970s, all truck scales were mechanical and installed in expensive concrete pits. Today, most heavy vehicle scales are installed above ground or in concrete pits with slab type foundations. With the benefit of new modular construction, scales can also be installed in a shallow pit, as opposed to the deep pit required by older mechanical scales.
One of the biggest reasons for choosing a pit type installation is space – or lack of it. A pit installation requires less space than a pitless installation due to the approaches, as sloped approaches to grade are generally required for pitless foundations. However, pit type scales require sump pumps and drains, and are more vulnerable to accelerated rust and corrosion due to the potential of standing water in the pit.