The Danish trailer manufacturer AMT has built horizontal tipper trailers for the construction of the Kopenhagen Subway system. The trailers have a hydraulic cylinder that pushes the cargo out without tipping. This is needed, cause tipping is impossible in the subway system.
The box is made of 6 mm Hardox 450 steel and is capable of transporting anything, from rock up to tarmac. With 4 BPW axles these trailers comply to the new Danish GVW law that allows 56 tonnes. Net payload is 38 tonnes.