Why is the flangeway on the LR55 deeper than the British Standard BS 3 tramway rail?
A. It is the same as the EU Ri60 flangeway/groove, 36mm (1 & 7/16 in) wide and 50mm (1 & 15/16in) deep. The logic for this is that it will also accommodate mainline rail wheels, which have wider and deeper flanges than tram/light rail vehicles. In many EU countries there is some sharing of tracks, eg. for the movement of rail freight wagons into city factory sites, using tram tracks, and as at Karlsruhe and Saarbrucken, light rail vehicles run over main line railway tracks (not to mention San Diego), so need wider tyres and deeper flanges to negotiate railway switches and crossings. In the EU this is normally achieved by the use of a hybrid wheel profile, first developed in Frankfurt am Main, where the tyre is 135mm wide (tram 85mm main line 180mm), and the flange is 30mm deep (cv 20 and 40). To allow for rail wear, the groove has to be deeper than the flanges. The only place in Britain where rail freight wagons shared tramway tracks was Glasgow. Here the unique track gauge of 4ft 7.75
