Kassel Sonderbord
In 1996 the DIN German Institute for Standardization issued the DIN 18024 part 1 ("Barrierefreies Bauen - Teil 1: Straßen, Plätze, Wege, öffentliche Verkehrs- und Grünanlagen sowie Spielplätze; Planungsgrundlagen" / Barrier-Free Design - Part 1: Streets, Places, Roads and Recreational Areas; Planning Basics) that was updated in 1998. Kassel had been on the forefront with performings tests with low-floor busses as early as 1992. A simple increment on the bus platform height however showed problems with wear on the bus tyres - the planning department of the Kassel Public Transport Company began to assemble ideas on a "special curb" (giving the name "Sonderbord") for their bus stops since 1994. A manufacturer was found in the company Fröhlich Bau AG in Gesungen south of Kassel with their patent kerbstone (EP0544202/1993). After its termination the manufacturing was taken over by the company Profilbeton GmbH in Borken, Hesse (also south of Kassel). Up to 2001 about 1/6 of the bus stops in Kassel had been converted to the "Kasseler Sonderbord" product.
The function of the Kassel kerb is to guide the tyre 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 stone has become a common design element in contemporary bus stop design - the provisions of the DIN 18024-1 have been proposed in 2010 to become a section of DIN 18070 („Öffentlicher Verkehrs- und Freiraum“ / Public Transport and Open Spaces).
Read more about this topic: Kassel Kerb