This is a steam era British Railways wheel stop inspired from several photographs taken on February 27th 1965 at Crewe North MPD. These wheel stops were bolted to the ends of the rails at the end of inspection pits and other locations throughout the depot.
The model featured here has the wheel stop attached to a segment of rail. You would print two wheel stops and attach them to the rails at the end of your inspection pit. They can be glued directly to the rail or to the baseboard. The triangular section and bolt pattern should be facing inward.