I came into possession of a number of drawings relating to its design/construction today. Haven't had a chance to properly look through them yet but they include details (route; manhole positions; shaft positions; duct connections; etc) on the Holland Street, Bath Street, Hope Street and Cathedral Street sections. Generally, the tunnel is 2m internal diameter but there are a few short sections of 5m internal diameter.
The drawings were dated between 1970 and 1974 so it would seem the tunnel was built in the early/mid 70s. Taylor Woodrow were (one of) the contractor - they had 4 or 5 site compounds along its length with the largest compound taking up the land that the Buchanan Galleries multi-storey car park is now built upon.
Anyway... didn't have much time but I thought I would tantalise all the tunnel aficionados by uploading the drawing of the most visible part of the tunnel apparatus - the lift shaft building, or machine room as the drawing calls it, at the junction of Cathedral St / North Hanover St. I only had access to an A3 scanner so had to do it piece by piece.
Enjoy...
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