Abstract: The invention relates to the construction of culverts, tunnels or the like. One known method of constructing a culvert uses precast reinforced concrete units which are heavy, require mechanical handling and are expensive to transport. Another known method is to construct a culvert by building brick or concrete walls and erecting a concrete roof. This method is also expensive and is a time consuming operation.The specification discloses a prefabricated culvert unit comprising opposed side walls joined by a top wall and wherein each side wall terminates in a foot member extending substantially normal to the wall, the unit being constructed from glassfibre reinforced cement (GRC). The feet members are supported on and secured to a concrete base surface in such a manner that there is a liquid-tight seal between the feet and the base surface. Concrete is then poured around the side walls and over the top wall of the unit or a plurality of units joined in line to complete the culvert.