Curb cut

A curb cut (U.S.), curb ramp, depressed curb, dropped kerb (UK), pram ramp, or kerb ramp (Australia) is a solid (usually concrete) ramp graded down from the top surface of a sidewalk to the surface of an adjoining street. It is designed primarily for pedestrian usage and commonly found in urban areas where pedestrian activity is expected. In comparison with a conventional curb (finished at a right angle 4–6 inches (10–15 cm) above the street surface) a curb cut is finished at an intermediate gradient that connects both surfaces, sometimes with tactile paving.
Historically speaking, footpaths were finished at right angles to the street surface with conventional stepped curb treatments. Their introduction to help people pushing prams dates back at least as far as the 1930s in the UK.
Kalamazoo, Michigan installed curb cuts in the 1940s as a pilot project introduced by veteran and lawyer Jack H. Fischer to aid employment of veterans with disabilities. A major project in Berkeley, California led by the grassroots Center for Independent Living led to curb cuts up and down Telegraph and Shattuck Avenues creating an extensive path of travel. Following this, the value of curb cuts was promoted more strongly and their installation was often made on a voluntary basis by municipal authorities and developers.
Curb cuts in Western countries have been mandated by legislation such as the Americans with Disabilities Act of 1990 (ADA) in the United States (which requires that curb cuts be present on all sidewalks) or the Disability Discrimination Act 1992 in Australia. The legislative requirements in some jurisdictions have been increased from the original requirements in recent times, to the point where existing treatments can now fail to meet the most recent design requirements.
When the ramps are used by a broader population than just the disabled, for whom the curb cut requirement was legislated, this new convenience can be seen as a positive externality, and has become known as the curb cut effect.
Curb cuts at intersections allow for people with disabilities, such as wheelchair users, to move around safely, independently, and with less difficulty. Curb cuts typically feature tactile paving, a pattern of circular bumps that indicate to visually impaired pedestrians that they are about to enter a roadway. Curb cuts also benefit pedestrians, as well as people with a wheeled form of transport, such as cyclists or people with carts.
A wider curb cut is also useful for motor vehicles to enter a driveway or parking lot on the other side of a sidewalk. In the UK this is commonly referred to as a 'crossover'.
Smaller curb cuts may be used along streets, parking areas or sidewalks in the manner of a water bar; by redirecting water from traditional drainage ways to stormwater BMPs which allow infiltration, such as a grassed area or rain garden.
Accessible curb cuts transition from the low side of a curb to the high side (usually 15 cm or 5.9 in change in level). Accessible curb ramps are a minimum of 1 metre (3.28 ft) wide. They are sloped no greater than 1:12 (8.33%), which means that for every 12 cm (4.7 in) of horizontal distance, they rise no more than one centimetre (3⁄8 in). The concrete curb ramp is sometimes scored with grooves, the texture of which may serve as a warning to vision-impaired persons of the transition to the street. Such grooves also allow for traction and water runoff, and may be stained a color that significantly contrasts with the adjacent concrete. If a curb ramp contains flared sides, they are usually no greater than 1:10 (10%) slope.
Pram ramps in Australia are designed according to Australian Standard AS 1428: Design for access and mobility.
Proponents of universal design often point to the curb cut effect as an example when raising awareness of the benefits of this design philosophy.