[Talk-GB] mapping tunnels

Thom Shannon thom at glow-internet.com
Thu Sep 27 23:19:26 BST 2007

Does anyone have any suggestions how to map a long tunnel? I know how to 
tag the ways, the issue is where does the tunnel go. You can't exactly 
get a GPS trace! I want to map the tunnels under the Mersey. The 
queensway tunnel has 3 exits, all at slightly odd angles and there is a 
junction in the middle of the tunnel.

Do you think I could figure out some reasonable positions using a cars 
odometer and a compass? Or does it not really matter that much?

Another option just occurred, the tunnel was started in 1925, so any 
maps from that era would be out of copyright. Perhaps a trip to the 

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