RU:Key:kerb

A kerb (American English curb) is the edge where a road meets a sidewalk. As these are transition points between different surfaces and/or elevations, the locations of kerbs are important features to pedestrians, cyclists, and especially to those with reduced mobility (e.g., in wheelchairs).

The key is kerb=*, and is used on the node of a highway=footway, highway=cycleway, or highway=path at the location of the kerb (at the edge of the street). If the kerb is identical on both sides of a crossing, it is possible to add the kerb=* tag to the highway=crossing node, which sacrifices accuracy for simplicity, consider using kerb:left and kerb:right if the kerbs differ.

Note: As a policy OSM uses  British English terms for most tags in preference to  North American English. In this case kerb=* rather than curb=*.

Tagging

Possible values for the tag are shown in the below table. Keep in mind that the heights given are only indicative, choice of a particular value should depend only on functional considerations. In other words, it is better to consider wheelchair/bicycle accessibility rather than the specific height of the kerb when choosing a value.

Value	Typical height	Typical use	Description	Example
raised	>3 cm	Bus stops & older kerbs	Raised above the norm, sufficiently to prevent traversal by wheelchairs, as well as to impede bicycles. Typical at bus stops to provide at-level access on and off buses. At least in the US, this is also the most common kerb at footway crossings before recent accessibility regulations came into existence. (Note: may be considered normal or yes pending discussion.) Note that the primary feature of Kassel kerbs, used at bus stops, is contouring to alleviate tyre rubbing when buses stop (not having a raised level), which is not specifically mapped. Aside from the general method, this can also be added to the highway=bus_stop node or platform node/way. Implies wheelchair=no, and may be used to increase the cost of travelling over this kerb by bicycle.
lowered	~3 cm	Crossings & driveways	Lowered kerbs are often found at crossing and driveways. They help ensure the crossing can be used by wheelchair users and allow access to drives. Implies wheelchair=yes. Some names for objects that fall into this category include driveway apron, curb cut (U.S.), curb ramp, dropped kerb (UK), pram ramp, and kerb ramp (Australia). Use this as a replacement for sloped_curb=yes or both.
flush	~0 cm	Crossings & driveways	Similarly to lowered, except the level transition is unlikely to be apparent, to blind users, by tactile sensation. Implies wheelchair=yes. It is important to map tactile paving at these locations.
rolled	N/A	Residential streets	Rolled kerbs still provide a gutter for water while being traversable by large wheeled vehicles, such as cars and bicycles, but not wheelchairs. They are generally used in lightly trafficked areas, such as planned residential areas, being insufficient for commercial or industrial roads. Implies wheelchair=no. Do not confuse with kerb=lowered, which are traversable by wheelchairs.
	N/A	Driveways	A typical curb for driveways traversable by vehicles and bicycles, but not wheelchairs, due to too high degrees. Implies wheelchair=no.
yes	Any		Some sort of kerb is present, but it can't or hasn't yet been determined whether it is raised, lowered, flush, etc. This may be useful when mapping via aerial imagery (prior to field survey) or if the exact type of kerb can't be recalled. Cautious routers could consider this to mean wheelchair=no, so whenever possible this value should not be used other than on a temporary basis.
no	N/A		No kerb is present. This may be useful to make it clear there is no kerb present if there used to be a kerb at this location.

kerb:height=<height><unit>

If exact height of the kerb is know this can also be marked using the tag kerb:height=*. Please state the unit used in the tag.

Examples

Type	Tagging
Raised, regular and lowered kerb in the same photo	This shows a raised kerb at the tram stop, a lowered next to it at the crossing, and a regular one closest to the viewer.
Two crossings with lowered kerbs	Red nodes are tagged with kerb=lowered, crossing ways are marked with highway=footway and footway=crossing, crossing nodes are tagged with highway=crossing and crossing=traffic_signals.
Bus stop with raised kerb	Add to either the bus stop or the platform kerb=raised. It is assumed the kerb tag refers to the edge between the road and the platform. If you wish to explicitly map, tag the actually kerb as the way on the platform area.
Crossing over a traffic island with kerb	Use kerb=lowered on the nodes of the footway at the locations of the kerbs. Assuming both sides of the crossing are the same this could be added to the crossing node.
Crossing with flush kerb & tactile paving	Use kerb=flush and tactile_paving=yes on the nodes of the footway at the locations of the kerbs. Assuming both sides of the crossing are the same this could be added to the crossing node.

Applies to

The proposed tagging applies to nodes and ways. When tagging ways please ensure you also apply the tag to any node where two ways intersect to help data consumers.

Rendering

A renderer may choose to use a symbol on these nodes to indicate the type of kerb, or perhaps wheelchair accessibility.

Related tags

The kerb=* node can also be tagged with tactile_paving=* to assist vision impaired individuals, and is especially important on kerb=flush nodes.

See also barrier=kerb.

Features/Pages affected

• Proposed features/sloped curb - amenity=sloped_curb and sloped_curb=* would be deprecated by kerb=*, except in certain cases (to be discussed)

RFC

An RFC was sent to the tagging list on 2011/06/21, Feature Proposal - RFC - Kerb.

• 2011/06/22 - Per mailing list discussion, changed unknown to yes, and added back no value. Also made heights indicative and emphasized functional definition.

Open issues

1. kerb:height - default unit
2. kerb tags on ways
3. Add a normal tag and use raised for bus platform type kerbs*
4. Remove height guidance and base on local norms*

*From tagging mailing list

Document kerb:left and kerb:right for asymmetric kerbs tagged on a crossing node.

Use as sub-key for barrier=kerb.

See also

• Steps features
• Barrier
• Wheelchair
• Tactile paving
• Proposed features/Traffic island
• Proposed features/sloped curb
• Proposed features/right left
• Relations/Proposed/Area

External links

• Wikipedia articles on kerb, and curb cut
• FHWA: Designing Sidewalks and Trails for Access, Chapter 7. Curb Ramps - From the US Federal Highways Administration, more than you could ever want to know about curb ramps. Other chapters from this guide might also be useful.