Proposal:Turn signals
| Turn signals | |
|---|---|
| Proposal status: | Abandoned (inactive) |
| Proposed by: | Biff |
| Tagging: | traffic_signals:turn=* |
| Applies to: | 
|
| Definition: | tag for a turn signal |
| Statistics: |
|
| Draft started: | 2016-06-16 |
Proposal
This proposal describes how to use traffic_signals:turn=* to tag turn signals.
A lot of similarity exists with the existing definition of the :turn suffix (see turn=*).
The proposal also provides a solution for tagging of the information provided by additional signs like "no turn on red".
Rationale
This information can be used by a navigation system to remind the driver that a separate turn signal exists at the crossing. This can be very helpful for drivers who don't know the area and might not notice the turn signal.
Examples
Turn signals are very common. Taginfo currently counts almost 30k traffic signals. It is likely that several hundred to several thousand of these traffic signals have separate turn signals.
Tagging
The general syntax of the tag is as follows (fields in square brackets [..] are optional):
traffic_signals:turn[:<transportation mode>][:<direction>] = <turn-value>[;<turn-value>][|<turn-value>][|<turn-modifier-value>]
Key
Transportation mode
This key-part specifies the vehicle category or transportation mode to which the traffic_signal applies, e.g. bicycle, motor_vehicle, foot, agricultural.
See Key:access#Transport mode restrictions for the full transportation mode hierarchy.
Direction
Traffic signals are typically direction-dependent. Use forward and backward to indicate in which direction the restriction applies. The value depends on the direction in which the way is drawn in OpenStreetMap. For guidance on how to identify this in your editor, see the description of the terms "forward", "backward", "left", and "right". This key-part can be omitted in the case of a oneway road.
Values
<turn-value>
Many values of :turn are re-used with the addition of the value "all", see below.
| <turn-value> | Description | Example |
|---|---|---|
| all | normal traffic light without any turn indication | 
|
| left | left turn (only) | 
|
| through | going straight through (only) | 
|
| right | right turn (only) | 
|
| reverse | reverse/U-turn (only) |  apparently, such specific traffic signals exist in South Korea (topmost light in picture)
|
To tag what is shown by several traffic lights, the vertical line "|" and the semicolon ";" can be used as follows:
- The semicolon
;separates values if more than one value apply to one traffic signal. - The vertical line
|separates values if several traffic signals are present.
It is common that several identical traffic signals are installed. This is typically done to ensure good visibility in all conditions and does not assign traffic signals to specific lanes. If several identical traffic signals are present, each kind of traffic signal is only tagged once. E.g. do not use traffic_signals:turn=left|left|right|right, instead use traffic_signals:turn=left|right. A left to right order (left|through/all|right) should be used.
Please note that the vertical line "|" does not indicate per lane signals, and the :lanes suffix (see Lanes) is typically not used. (If needed, an extension like traffic_signals:turn:lanes:forward=* would probably be possible, but it's not part of this proposal.)
<turn-modifier-value>
| <turn-modifier-value> | Description | Examples |
|---|---|---|
| right_on_red | right turn on red is permitted |
|
| left_on_red | left turn on red is permitted |
|
| none_on_red | turn on red is not permitted |
|
| not_right_on_red | right turn on red is not permitted |
|
| not_left_on_red | left turn on red is not permitted |
|
Please tag only what you can see. Especially rules for turning on red should only be tagged if a relevant sign exists - don't tag the default rule that is provided by local law.
Examples
Traffic signal only for traffic that turns left
- Create node on highway at the stop line. (Don't tag the node where two highways cross.)
- Tag the node with highway=traffic_signals.
- Add traffic_signals:direction=forward (or backward). This is not needed in the case of a one-way road.
- Add traffic_signals:turn:forward=left. A traffic signal is only present for traffic that turns left! There is no traffic light for the general traffic that passes straight ahead over the crossing and the general traffic does not have to stop at the stop line. This is only possible because the traffic that turns left enters a one-way street. Of course this is a very rare case - but it started the idea for this proposal. Since this is a rare case, it might be a good idea to add a note=* that explains the situation. (The picture was taken in a different place.)
Normal traffic signal for all traffic
- Create node on highway at the stop line.
- Tag the node with highway=traffic_signals.
- Add traffic_signals:direction=forward.
- You could add traffic_signals:turn:forward=all to specifically indicate that this is just a normal traffic light, but it's not really required as this is the default.
Traffic signals for all traffic plus a separate signal for traffic that turns right
- Create node on highway at the stop line.
- Tag the node with highway=traffic_signals.
- Add traffic_signals:direction=forward (or backward).
- Add traffic_signals:turn:forward=all|right, as separate traffic signals are present for general traffic (solid red/yellow/green lights) and traffic that turns right (typically a colored arrow).
Traffic signals for traffic that turns left or passes through plus a separate traffic signal for traffic that turns right
- Create node on highway at the stop line.
- Tag the node with highway=traffic_signals.
- Add traffic_signals:direction=forward (or backward).
- Add traffic_signals:turn:forward=left;through|right. There's a traffic signal that shows a double arrow that points left and straight ahead plus a separate traffic signal with an arrow that points right.
Right turn on red
- Create node on highway at the stop line.
- Tag the node with highway=traffic_signals.
- Add traffic_signals:direction=forward (or backward).
- Add traffic_signals:turn:forward=all|right_on_red.
Traffic signal only applies to a specific transportation mode
You can use the applicable suffix for the transportation mode, e.g. if there is a bicycle lane on the highway and a specific traffic signal exists only for bicycles that turn right then you can use the :bicycle suffix to create the tag traffic_signals:turn:bicycle:forward=right.
Right turn on red for bicycles
The sign shown in the image has only been proposed and does not (yet?) exist on public roads in Germany. However, similar signs may exist in other countries. Such signs could be tagged by first tagging the general traffic signals and then adding the specific traffic signals that apply for bicycles, e.g. traffic_signals:turn:bicycle:forward=all|right_on_red.
Related Cases
- For turn restrictions that are independent of the traffic signals, e.g. "no right turn", see Relation:restriction.
Current usage
Applies to
This proposal only applies to nodes.
Rendering
The information captured by this proposal is probably too detailed to be shown on a map.
A navigation system might show traffic lights with solid red/yellow/green lights or colored arrows as appropriate.
Features/Pages affected
- highway=traffic_signals
- Not to be confused with traffic_signals:arrow=*
- protected_left_turn=*, undocumented but sometimes used, see taginfo
External Discussions
- Discussion in OSM forum (German)
Comments
Please comment on the discussion page.