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Tunnel/altitude oddity

Sunday 11 February
by SoreTween
in forum
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Hi Richard,

Have a look at the altitude profile for this journey:

At the tunnel under the waypoint the profile goes over the top of the mountain.  Now reverse the route, the peak has disappeared, the altitude profile goes through the tunnel.  There's nothing obvious about the tunnel on OSM that might be the cause, there's a similar tunnel with the same tags 1km East on that route that is correctly profiled in either direction.




Sun 11 Feb, 18:51

I think this is a result of the route instructions being ‘collapsed’ – i.e. when the raw instructions generated for the route (often just ‘Straight on’, ‘Straight on’, ‘Straight on’!) are compressed down to only the important ones. My guess is that in one direction, the change to a tunnel is being mistakenly elided. I’ll have a poke around and see if that’s the case.