Proposed features/Relation:type=traffic control
The proposal suggests yet another alternative for specifying stop signs, give way signs and similar traffic controls at junctions.
The location of traffic control signs can be very useful for route planning. The existing Tag:highway=stop tag doesn't provide any effective mechanism for flexibly specifying signs at complex junctions including:
- Four-way stops
- Two way stops
- Junctions where more than two roads cross
- Junctions with one-way streets
- Junctions where one street doesn't have stop signs
- Junctions with both stop and give way signs
The stop tag also cannot model a stop/give-way sign in the middle of a way, only at the end. This means that if you have a road which must stop/give-way at multiple intersections, it must be split into pieces.
New relation applied to ways and nodes participating in junctions.
Usage Tags and Values
|sign||no is used when there is no sign for this control, only road markings or similar ||
For each junction that has signs, a new relation should be created with type=traffic_control. The relation is applied one node and one or more ways. For any way included in the relation, signs are specified at the junction for each direction in which traffic flows into the junction.
If there is a junction where one road has to give way and one has to stop, this can be tagged by adding both ways to the one relation with the appropriate roles.
If there is a two-way road that traverses the junction, but only has a sign applying to one direction, the way must be split, and only the way that has a sign at the junction should be added to the relation.
At high magnifications, renderers could render traffic signs symbols at the appropriate locations in the intersection. The proper placement of the icon on a rendered map will depend on whether the rendered locale is one where people typically drive on the right or left side of the road, but hints can be given by adding node(s) with the role of 'sign' to the relation.
Route finding applications could use the presence or absence of traffic control signs to help find efficient routes. This is especially true when calculate routes for cyclists, or routes that are avoiding motorways.
Things to consider
- "Stop if the traffic lights are out" signs
- Are there other traffic-control signs that could become part of this proposal?
- There are right-of-way signs --Skyper 12:00, 5 November 2009 (UTC)
- I think also traffic_signals should be considered as stop signs --Skyper 12:03, 5 November 2009 (UTC)
- Maybe not as stop signs, but how about traffic_control=signal --turbodog 17:48, 6 November 2009 (UTC)
- Would flashing lights (red and yellow) be tagged as stop and giveway signs, or treated separately? Most often they are in combination with signs, but not always. However flashing yellow often appears in conjunction with flashing red, in which case it just means "caution" or "yield to traffic in the intersection" not "yield to oncoming traffic.--turbodog 17:49, 6 November 2009 (UTC)
The many alternative proposals (if this one is liked enough)