Wonder of Georgian engineering

Underground tunnel discovered during Princes Street tram works

Sections of a 19th century underground tunnel were uncovered by tram works on Princes Street.

The Crawley tunnel was constructed around 1821 to carry two water pipes from the Crawley and Commiston springs under the Old Town to feed the expanding New Town.

The sections of the tunnel discovered at the mound are stone built, internally about 5ft across and 6ft high – fantastic examples of Georgian civil engineering.

John Lawson, curator of archaeology for the city, said: “The significance of the discoveries lies in the fact that we have uncovered a new section of the tunnel running north-south towards the middle of the adjacent Royal Academy.

“This building was built in two phases from 1825-1836. Like the tram, the construction required the moving of essential services, in this case the diversion of the Crawley tunnel to the west around the Academy and under the road going down the mound.”

Crawley Tunnel is owned by Scottish Water and is still in use. Currently the roof is badly damaged. To repair the damage and make way for the tram tracks, the arched roof of the Crawley Tunnel will be removed and fully recorded by the city archaeologists.

The top will then be bridged over with a new, lower roof put in place. The surface can then be fully reinstated while preserving the tunnel under the new tram tracks.