A Kassel kerb is a concave-section made for buses kerb stone

Curb (road)

A curb, or kerb , is the edge where a raised pavement/sidewalk/footpath, road median, or road shoulder meets an unraised street or other roadway.-Function:...

 which is intended for use at bus stop

Bus stop

A bus stop is a designated place where buses stop for passengers to board or leave a bus. These are normally positioned on the highway and are distinct from off-highway facilities such as bus stations. The construction of bus stops tends to reflect the level of usage...

s served by modern low floor bus

Bus

A bus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are...

es which have improved accessibility

Accessibility

Accessibility is a general term used to describe the degree to which a product, device, service, or environment is available to as many people as possible. Accessibility can be viewed as the "ability to access" and benefit from some system or entity...

 for mobility-impaired people.
The Kassel kerb guides the tyre

Tyre

Tyre is a city in the South Governorate of Lebanon. There were approximately 117,000 inhabitants in 2003, however, the government of Lebanon has released only rough estimates of population numbers since 1932, so an accurate statistical accounting is not possible...

 of the stopping bus in a such a way as to improve the alignment of the bus's doors with the kerb and slightly raised boarding platform. It does this because as the tyre rides up the concave surface, gravity pulls it back down and steers the bus into alignment. The Kassel kerb takes its name from the German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 city of Kassel

Kassel

Kassel is a town located on the Fulda River in northern Hesse, Germany. It is the administrative seat of the Kassel Regierungsbezirk and the Kreis of the same name and has approximately 195,000 inhabitants.- History :...

, where it was first introduced.