It's not the load: the loading gauge refers to the maximum dimensions of a train. In the UK, the vast majority of lines bridges and tunnels are simply far too l

It's not the load: the loading gauge refers to the maximum dimensions of a train. In the UK, the vast majority of lines bridges and tunnels are simply far too low to allow for double-decker coaches; the only ones ever used had pretty weird offset compartments: see <http://dart75.tripod.com/cutaway.gif> http://dart75.tripod.com/cutaway.gif> for a cutaway diagram.