The single bores are so narrow that if a stationary train has to be evacuated during an emergency, there is insufficient room to open any side doors against the tunnel walls. Consequently, there has always been a requirement that any passenger train passing through has a corridor connection free from obstruction on at least one end. Non-corridor stock and top and tailing of passenger trains was accordingly banned, although a 1985 railtour did slip through the net. The same prohibition was going to apply to the Class 395 Javelins, depriving Dover of its quickest route to the Channel Tunnel Rail Link. It was only by slewing the track very slightly to one side, to create sufficient room to access the evacuation points that were then created in the tunnel's cross-passages, that the rule could be relaxed for the Javelins.