Download this guide as a Word document
A. Introduction
This guide sheet describes and compares a range of common kerb profiles, including where they are often used, access considerations and better options where available.
You may also find our guide sheets on gradients, crossfalls, flush kerbs and designing accessible dropped kerbs helpful, together with further guidance on the Wheels for Wellbeing resources page.
Key points:
-
Kerbs have multiple functions, including providing a clear separation between different spaces for all users, holding surfaces in place, and channelling water flow.
-
Any non-flush kerb or edge creates a trip/wheel catch hazard and reduces accessibility of a space for many Disabled people.
-
Continuous tactile edges including kerbs between footways (pavements) and carriageways are necessary for public realm accessibility.
-
Kerbs lower than 60mm are not detectable for some Blind and visually impaired people. Where kerbs are lower than 60mm, tactile paving is often needed.
B. Common kerb types
1) Flush
A flush kerb is part of a completely level transition between two surfaces – often a footway (pavement) and carriageway. See Wheels for Wellbeing guide to flush kerbs for more details, including why dropped crossing kerbs should always be flush.
2) 6mm bullnose
This is the maximum permitted height for a crossing dropped kerb in government Inclusive Mobility (2021) guidance. However, even a 6mm step creates a difficult transition for many Disabled people as it can catch feet, wheelchair casters, canes and sticks. Flush kerbs (above) are more accessible. If a slight height change is needed for drainage or cleaning, then a slope on a flush kerb is better than a stepped kerb.
3) 25mm 900
Current government tactile paving guidance recommends a 25mm kerb upstand at all vehicle crossovers ( usually driveways) for detectability for visually impaired people. However, 25mm upstands are not detectable for many visually impaired people, and 25mm kerbs create a serious trip hazard and barrier for many mobility impaired people, especially for people using wheelchairs and other wheeled aids. We recommend accessible dropped kerb design for vehicle crossovers using preformed Dutch entry kerbs or, where more appropriate, flush kerbs with tactile paving.
4) 50mm delineator
This specialist kerb is used to separate cycle tracks and footways which are at the same height. It is used together with ladder and tramline tactile paving. Since there is no height difference between the footway and cycle track, it is often hard for people walking/wheeling and cycling to tell which side is meant for which users. For better detectability and separation of people walking/wheeling and cycling, we recommend installing the footway above the level of the cycleway, separated by a 60mm splayed kerb.
5) 60mm 900
60mm is the lowest kerb found to be consistently detectable for Blind and visually impaired people (testing was with 60mm vertical chamfered kerbs and bullnose kerbs). 60mm kerbs create a significant trip hazard and are impassable to many Disabled people, but are more accessible for many people than higher kerbs. 60mm kerbs are also less likely to trip people or catch cycle wheels or pedals, so are generally safer than higher kerbs.
6) 60mm splayed
Splayed kerbs are much more accessible to Disabled people wheeling and cycling than vertical kerbs of the same height: They create much less of a trip, wheel and pedal catch hazard than vertical kerbs. Splayed kerbs can be obtained with various splay angles – often 30, 45 and 60 degrees from horizontal. Anecdotally, 60mm splayed kerbs are detectable for some and possibly most Blind and visually impaired people, but the accessibility of these kerb profiles has not been appropriately tested yet, and needs to be.
7) 120mm “standard”
A majority of “standard” street kerbs are between 100 and 150mm. 120mm kerbs are impassable for many mobility-impaired people, including most people using wheeled aids and people who need a handrail to use steps safely. It is difficult to create accessible dropped kerbs associated with 120mm kerbs as associated gradients will usually be too steep: Crossings and driveway crossovers on these streets are likely to badly reduce footway accessibility, especially if the street is sloping. 120mm kerbs are not able to protect pedestrians from drivers: In this case, bollards or comparable alternatives are required.
Kerbs between 100 and 150mm should no longer be considered the standard: They should only be used when there are particular reasons to choose this height, such as at a bus stop. Instead, the standard kerb height should be 60mm, as above.
8) 200mm high
Kerbs up to 200mm high are common and even less accessible than 120mm kerbs. Associated dropped kerbs will almost always have very steep, inaccessible gradients. 200mm kerbs can be mounted by SUVs and other larger vehicles without difficulty: They will not protect pedestrians from drivers. 60mm kerbs are usually a better option.
9) Dutch entry kerb (~60+mm)
These sloping kerbs are used where drivers are allowed to cross pavements at driveways. Corner pieces to transition to the standard footway kerb are available. These preformed kerbs help installers create level, accessible footways and minimise crossfall. They have a steep slope to slow drivers and minimise their impact on footway width (often 1:10), but it’s very short, so these kerbs can still provide useful accessibility to many users of cycles and other wheeled mobility aids (see Inclusive Mobility (2021 and BS8300-1:2018).
10) Bus stop kerb (~150mm)
Bus stop kerbs have a range of heights, usually between 125mm and 140mm, and various shapes, depending on the choice the local authority has made in discussion with bus service providers. Non-vertical kerb profiles can reduce risk of damage to bus wheels as the bus pulls up. Bus stop kerbs are usually higher than standard kerbs, so that bus ramps are not too steep to use. Bus stop kerbs can be lower when the buses have a kneeling function.
11) HGV protection kerb (300+mm)
These high profiled kerbs are often used in narrow access points where HGVs will often be turning, for example into depot or superstore entranceways. They are shaped to help protect people and property behind the kerb, as it is difficult for HGVs to mount them accidentally. These high kerbs should only be used where a clear need is identified.
12) Stacked kerbs (bespoke heights)
Often found as a bespoke solution in locations where a footway and carriageway or verge have ended up at different heights. High kerbs reduce safely usable footway width due to increased risk of injury from falls. They should only be used where it is unavoidable and edge protection should be considered in risk assessments.
13) Other kerb considerations
There are many other heights, profiles and types of kerb. For example, path edges often have 25mm retaining kerb edges between the path and grass or borders. Decorative kerbs including edgings made of brick, tile, timber and other materials are sometimes used, which can impact on accessibility. Granite and other natural stone kerbs can have a marked negative effect on accessibility and usable pavement width, especially in wet or icy weather.