These weighbridges are installed in a pit, keeping them flush to the road surface. Because these bridges do not require ramps, they take up less surface area, making them ideal for smaller areas or sites where space is at a premium. Initial civil and foundation work can make pit installations a more expensive option. A pit is also prone to piling of debris and water logging, requiring provision of sump-pumps and manholes for maintenance purposes. Guide-rails are not required for pit mounted bridges.