Roads are rendered really "fat"

Posted by Picard-Lindelöf on 20 November 2018 in English (English)

I am noticing that on the rendered map, roads are rendered as really thick lines, which makes complicated intersections in cities look pretty ugly unless you reaaally zoom in on them. For example, I am working on this area

You cannot really even see all the roads as separate roads although the two motorway links (in between the tunnels) to the west of the square are actually drawn 10 meters apart. To the east of the square it is even more of a mess...

Since we create OGF maps for enjoyment and aesthetic beaty, my question is: How do you deal with this?

Have I drawn this way too small? Or should I just ignore it?

Comment from Rustem Pasha on 20 November 2018 at 20:56

Openstreetmap street rendering always was too thick to accurately present roads. As of today it is far better than because the connectors are thinner what allows to draw better interchanges.

But in fact your roads are a bit too small. For example width of one traffic lane usually vary between 2.75 to 4.0 meters (the higher road class the wider) and additionally the roads have shoulders (additional 1.5-2,5 meters) on their outer border. There is also in two way roads like highways cntral reserve (minimum two meters) and inner shoulder with the size of 0.5 metter. That means average two way (two lanes each) highway should have 2*(2.5 m + 2*4.0 m+0.5 m) + 2 m = 24 meters. In the highway of that width (here) you put additionally:

  • tertiary road - 2*(2.0+3.5) = 11 meters.

  • crossroads T-type - 12 meters curve (unfortunatelly invisible on the map)

  • a curve on the access road - another 12 meters.

  • access road itself - 4.0 m +2*0,5 m = 5 meters

  • two reserves - 2*2.0 m = 4 meters

So there is a lack of totally 44 meters of width.

Also when you change the layer you must change the height of the road position about 5 meters. That means the access road should be minimum 200 meters long, in high class roads I recommend to double that value.

Hope that helps.

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Comment from Picard-Lindelöf on 20 November 2018 at 21:17

Thanks for the calculation! I am actually struggling a bit with this motorway tunnel. Outside the city it is easy to create big interchanges, but in the city with the tunnel it is more difficult.

I think I will have to remake the exits from the tunnel a couple of times before they are right...

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Comment from Rustem Pasha on 20 November 2018 at 21:25

I would recommend moving the northern way these 44 meters to the north and then move the access roads to the northern side of Erlentalerstrasse (keeping in mind the required lenght). Also the access to the southern way is too short. I would move it closer to the station and connext with Diedstrasse instead of Lilienstrasse. It's probably the least damaging solution.

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Comment from histor on 20 November 2018 at 21:26

And to the 44 m of the clculation of Rustem Pasha you need 8 to 9 m for a two-track streetcar line (or 7 m with 1.000 m spur).

And please do not set an end of the ramp direct at the tunnel. If the forking of the streets are in the tunnel, your ramp must end as tunnel. Or otherweise start or end of the ramp and the motorway lay on open space and at same level.

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Comment from histor on 20 November 2018 at 21:33

And why your S-Bahn west of Stephansplatz has a level crossing instead of a bridge over the southern track??

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Comment from Rustem Pasha on 20 November 2018 at 21:56

@histor I didn't consider the addition of space for the streetcar because it lays on the ground and can be put above the higway tunnel. Of course it causes some engineering difficulties but they can rather be ignored...

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Comment from Picard-Lindelöf on 20 November 2018 at 22:00

I have reworked the area we are talking about. It is now the type of motorway exit with the access roads running parallel to the actual motorway.

Now Lilienstraße has a turn at the end to connect to Erlentaler Straße a bit better.

The motorway tunnel has a width of about 30m and the access road lengths are now 120m in the tunnel plus 50m above ground each (only the one on the southeast is shorter)

The width between Lilienstraße and Erlentaler Straße and the rail tracks is about 10m, so the tram line should fit there.

It still looks a bit cramped but I think this is an improvement over the previous version??

Histor do you mean this crossing? Xou are right I should probably change it. But I think it will be enough to change it from a crossing to two croccovers so a train can change from the north track to the middle track and then from the middle to the south track

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Comment from histor on 21 November 2018 at 09:52

(Histor do you mean this crossing? ) - Yes. You have two S-Bahn lines with heavy traffic. State of the art then is no forking with a lot of switches. Uptown from Stephansplatz you may use only a switch, but downtown from northwest to Stephansplatz should be a flyover about the track from Stephansplatz to the southwest. Both tracks to Stephansplatz then run parallel and at Stephansplatz the trains on both tracks stop at both sides of a platform and then - after the platform - both tracks come together via a switch t one track to the east.

Now you have a lot of switches and allways the danger of colision of trains.

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