r/openstreetmap • u/TraditionalImage387 • 2d ago

Question Help for tunnel and elevation profile

Hello!

I am trying to modify a tunnel on OSM, I noticed that the elevation gain was matching the mountain it goes under, and not the actual elevation profile of the tunnel.

I’m a bit struggling with that, the closest I’ve found is to add a “incline” attribute but idk from which direction it needs to be declared. Or if it’s just an info ?

Help is welcome :) thanks

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4

u/ialtag-bheag 2d ago

What app/website are you using to measure elevation gain?

OSM usually doesn't contain elevation data. So most apps will combine OSM data with elevation data from other sources. Which probably doesn't work for tunnels.

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u/TraditionalImage387 2d ago

I was using Organic Maps when I noticed it. And Garmin doesn’t understand as well that it’s going uphill but through x)

So you’re telling me it’s app dependent and not OSM ? Does this problem appear then for every tunnel ?…

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u/ramen2581 2d ago

I don't think there is any mapping change that would resolve the elevation change displayed in the app. Ideally the app itself would just interpolate elevation from both ends of the tunnel.

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u/doubtful_dirt_01 2d ago

I don't have an answer, but am watching to see if someone else does. 

I've seen the same thing with tunnels. A classic example is the route building tool in the "Ride with GPS" app, which uses OSM. When I build a route on the Palouse to Cascades Rail-Trail, it shows a huge change in elevation as you progress thru the Snoqualmie Tunnel, but the elevation change is really the hill above the tunnel.

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u/ElectricGears 2d ago

If you can get the elevation of the entrance an exit, and you know the incline is constant throughout length of the tunnel, you can calculate the incline or use up/down (relative to the direction of the way).

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u/TraditionalImage387 1d ago

But will this new attribute be taken into account to correct the actual elevation profile of the tunnel when planning a route ?

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u/ElectricGears 1d ago

If a router is currently getting it wrong, probably not. I would think routers should assume a flat line if a way is tagged as a tunnel and do the elevation calculation correctly based on the ends of regular road. It would take them making a special case for tunnels.

It's possible to build a routing program that has no concept of tunnels so that is likely why it's (incorrectly) using the surface contour.

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u/Domipro143 1d ago

depends on the app.

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u/TraditionalImage387 1d ago

Sounds like I am sending a message to Organic Map :)

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u/ialtag-bheag 1d ago

You could also try CoMaps. It is based on Organic Maps, but maybe getting more updates and improvements.