Tagging Lanelets and Areas

This page explains the general mapping scheme for Lanelets. The tags are used by Lanelet2 to infer information on the traffic rules. All Lanelets and areas must be “self sustained” which means that all traffic restrictions that apply to a Lanelet must be determined just by looking at the Lanelet. The following important informations have to be determinable:

• The driving direction (only for Lanelets, by default assumed to be one-directional)

• The road users that the Lanelet is intended to be used by (by default vehicles only)

• The speed limit (by default the maximum speed for urban regions)

In Lanelet2 no tag is mandatory, but if you want your map to behave reasonably, you should make sure that at least the above listed items can be correctly inferred.

Subtype and Location

The subtype tag determines what the actual type of the Lanelet is. It is used to determine the participants that are allowed to use the Lanelet as well as partly to determine the speed limit in the absence of SpeedLimit regulatory elements. The location tag is used to distinguish between urban and nonurban regions which can (depending on the country) affect the speed limit.

The subtype tag is not set, lane is assumed. If location is not set, urban is assumed. Note that speed limits can be mandatory or non-mandatory. Non-mandatory speed limits are only recommendations. The determined speed limit is the minimum of the actual speed limit and the average speed of a participant on this road type. If it was based on average speed, it is assumed to be non-mandatory.

Note that the values in the following table are just the values inferred by default. The actual interpretation depends on the chosen TrafficRuleobject in lanelet2_traffic_rules.

subtype	location	description	Inferred Participants	Speed limit
road	urban	A part of a road in urban region	All vehicles and bikes	City speed limit
road	nonurban	A part of a road in nonurban region	All vehicles and bikes	Nonurban speed limit
highway	urban	A part of a highway in urban region	All vehicles	Urban highway limit
highway	nonurban	A part of a highway in nonurban region	All vehicles	Nonurban highway limit
play_street	-	A part of a play street	Vehicles, bikes, pedestrians	play street speed limit
emergency_lane	-	Lane for emergency vehicles	Emergency vehicles	Average emergency vehicle speed
bus_lane	urban	Lane for buses	Bus, Emergency, Taxi	City speed limit
bus_lane	nonurban	Lane for buses	Bus, Emergency, Taxi	Nonurban speed limit
bicycle_lane	-	A lane that is usable only for bikes	Bikes	Average bike speed
exit	urban	Exit area of a house or garage that crosses the crosswalk	Vehicles, bikes, pedestrians	Urban speed limit
walkway	-	A part of a way for pedestrians	Pedestrians	Average pedestrian walking speed
shared_walkway	-	A way shared by bikes and pedestrians	Bikes, Pedestrians	Average bike/pedestrian speed
crosswalk	-	A part of a crosswalk	Pedestrians	Average pedestrian walking speed
stairs	-	Well … stairs	Pedestrians	Average pedestrian walking speed

Overriding

Since the inferred information above might be incorrect in some situations, it can be overridden by explicitly specifying participants or speed limit. If one of the participants is set like this, the subtype and location tags are ignored and all other participants are assumed to be disallowed. The allowed participants then have to be set one by one.

The following particiants can be used to define individual special situations. They are prefixed with the type of information they are supposed to override. Values are always yes or no:

• vehicle (affects all “motorized” participants) OR

  • vehicle:car OR

    • vehicle:​car:electric

    • vehicle:​car:combustion

  • vehicle:bus

  • vehicle:truck

  • vehicle:motorcycle

  • vehicle:taxi

  • vehicle:emergency

• pedestrian

• bicycle

To override the participant information, prefix the participants with participant:, e.g. participant:vehicle:car=yes. This would allow only cars on this Lanelet/area.

The normal vehicle tag can not be combined with any vehicle:xxx tag. If one of the vehicle:xxx tags is defined, all other vehicle:xxx tags must be set individually.

The speed limit can be overridden separately by using the follwing tags (speed_limit must be set, speed_limit_mandatory is optional):

• speed_limit (any velocity, preferably with unit, e.g. 5 km/h, no unit is inferred as km/h)

• speed_limit_mandatory (yes or no, default is yes)

For an even finer overriding behaviour, use speed_limit:xxx and speed_limit_mandatory:xxx, where xxx is one of the participants from above. If the fine overriding is used and no match can be found for the current participant, speed_limit is returned. If it is not set, 0 km/h is returned.

Note that the speed limit can be overriden by RegulatoryElements.

The general rule of thumb should be to avoid the overriding mechanism where possible. The information can be transported much cleaner by either creating a new TrafficRule class that covers road types that we do not cover or by using RegulatoryElements.

Example

Consider a lanelet with the following tags:

Tag	value
type	lanelet
subtype	road
location	urban
participant:vehicle:taxi	yes
participant:vehicle:bus	yes
participant:pedestrian	yes
one_way:pedestrian	no

Since overriding is used, the subtype/location combination is ignored when determining allowed participants. This means that only the following participants are allowed: Taxi, Bus, Pedestrian. Because the speed limit is not overridden, it could be determined (depending on the country) as 50 km/h (the speed limit for vehicles in cities) for taxis and buses and as non-mandatory 4km/h for pedestrians, since the average walking speed of a pedestrian is assumed to be 4 km/h which is smaller than 50 km/h.

The one_way tag - see the section “Direction” below - allows pedestrians in both directions (which is generally a good idea).

Other, Optional Tags

• road_name (the name of the road)

• road_surface (dirt, asphalt, concrete, …)

• region: the ISO 3166-2 code for the country in which this Lanelet/area is situated. The traffic rules might check this tag to ensure they are working on the correct part of the map.

Lanelet Specific

All Lanelets have type=lanelet. If the tag is not present, it will be added when saving to .osm, because this is a requirement for writing from/to osm files.

Note that the lane change restrictions are not inferred based on the Lanelet tags, but on the tags on the borders. See here for more info.

Direction

By default, Lanelets are one-directional. The direction is determined by the order in which the left and right bound is set. Whether a Lanelet is one- or bi-directional is determined by the one_way tag. If it is set to no, the Lanelet is bidirectional. The one_way tag can be further specialized to define the direction for different participants. This can be done by appending the type of the participant (as in Overriding), e.g. one_way:bicycle=no. This would mean that the Lanelet is one-directional for all participants, except bicycles. one_way and one_way:xxxx can not be used in combination.

Pedestrians use Lanelets always bi-directional, unless overridden.

Area Specific

All areas have type=multipolygon (!) for compability reasons with the osm file format. type=area is possible too but will be overwritten when writing map data to an .osm file.

More subtypes

Additionally to the subtypes described above, other tags can be used to define the environment of a road:

• parking

• freespace (road area without a purpose)

• vegetation

• keepout

• building

• traffic_island

These tags can be interpreted by special TrafficRule objects to determine the drivable space (e.g. for parking maneuvers or emergency situations).