[OSM-talk] Mapping and surveying long road tunnels

Robert (Jamie) Munro rjmunro at arjam.net
Thu Mar 22 14:32:00 GMT 2007

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Richard Fairhurst wrote:
> Steve Chilton wrote:
>> How would you survey the curving underground
>> alignment of the Limehouse Link? I suspect even the best GPS handheld
>> devices won't get a signal. You can't get any useful data from the Yahoo
>> satelite imagery. You can't use any published map sources that you
>> consider reliable as it is too new for o-o-cop maps.
>> Any thoughts?
> Half in jest, Nick Gagravarr and I were talking a while back about  
> using a motion sensor for underground surveying... such as the one on  
> the Nintendo Wii.

Or the one in a MacBook, or in the TomTom devices. I think they are
nothing like accurate enough, based on how my TomTom failed to tell me
to take the turn in time inside that very tunnel.

The other method for surveying would be to hook into a cars speed/trip
meter, and combine that with a compass for direction. You can probably
connect to the OBD-II connection on modern vehicles. There are nice
OBD-II bluetooth connectors that would be great for integration with
things like TomToms. http://www.car-pal.net/

On the other hand, who cares where the tunnel is. If we have the start
and end points, with the correct topology, and roughly the right length,
surely that is good enough. If we can't tell it's wrong by any
reasonable method of surveying, then it is right as far as I am
concerned. :-)

Robert (Jamie) Munro

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