Escape tunnel

An escape tunnel is a form of secret passage used as part of an escape from siege or captivity. In medieval times such tunnels were usually constructed by the builders of castles or palaces who wished to have an escape route if their domains were under attack. Prisoners have dug escape tunnels to flee captivity.

In road and rail tunnels, narrower escape tunnels are provided to enable people to escape on foot in the event of a fire or other accident. For example, between the two main bores of the Channel Tunnel is an access tunnel large enough for a fire engine.