The UK’s Royal Mail looks set to wind down Mail Rail, a unique network of mail tunnels under London, claiming that it is too expensive to operate.

“It serves fewer stations than originally intended and costs five times as much as moving mail by road,’ David Chapman, Royal Mail’s London programme manager said. “For a business losing £1.2M [US$1.9M] a day, that is clearly not sustainable.”

The announcement comes as the mayor of London, in a bid to cut traffic congestion, is levying an US$8 charge on vehicles entering the city, and shortly after the British Tunnelling Society established a parliamentary committee to advise the government on the better use of underground space.

Mail Rail opened in 1927, and runs along a track from Padd-ington in west London, to White-chapel in the east,

The 37km of track under London, running at depths of 21m, carries self-propelled rubber-tyred vehicles of speeds up to 64km/h, with a weight capacity of 980kg.

Alternatives for the network have been discussed and include using the tunnels to transport freight, freeing London’s congested roads.