Camber
Introduction
Cant is the transverse slope "Slope (geography)") that occurs in curves on the platform of a railway track or the carriageway of a road, in order to compensate with a component of its own weight, the inertia (or centrifugal force, although this name is not accurate) of the vehicle, and ensure that the total resultant of the forces remains parallel to the horizontal plane, acting as a centripetal force directed at all times towards the center of the curve. The objective of camber is to counteract the inertia that propels the vehicle towards the outside of the curve. It also has the function of evacuating water from the road (in the case of roads), requiring a minimum inclination of 0.5%.
The theoretical formula for the superelevation (valid for railways and highways), in the absence of friction, for a speed and a radius of gyration is:[1].
where is the cant angle. The superelevation is defined precisely as
this tangent, so it is a dimensionless magnitude.
Cant on railways
Contenido
En los ferrocarriles, el peralte ayuda a guiar al tren en la curva, evitando que las pestañas de las ruedas toquen los carriles, reduciendo la fricción y el desgaste. Las principales funciones de los peraltes son:.
El peralte necesario en una curva depende de la velocidad esperada de los trenes y el radio "Radio (geometría)") de curvatura. Sin embargo, puede ser necesario elegir un valor de compromiso ya que hay vías por las que circulan trenes lentos de carga y de alta velocidad. Generalmente los trenes lentos desgastan el carril interno, mientras que los de alta velocidad desgastan el carril externo.
Spain
In Spain, RENFE regulations measure superelevation as the difference in elevation between one lane and another. The formula used is derived from the general formula[2] with its maximum being:.
With a limit of 160 millimeters and a minimum stipulated in:.
Where L is the length of the transition curve in meters, V is the speed in km/h and R is the radius of the curve in meters.
Superelevation on roads
El peralte en carreteras se construye para compensar la fuerza centrífuga que hace que los vehículos salgan de la carretera. Cada país dispone de un reglamento o normativa que impone el porcentaje de peralte en función de los siguientes parámetros:.
The superelevation is stipulated by regulations.[3] It has a maximum of 8% on roads with a design speed greater than or equal to 100 km/h. On the rest of the roads the maximum is 7%. The formula used would be:
References
- [1] ↑ Universidad del País Vasco. «La fuerza centrífuga y la estabilidad de un vehículo».: http://www.sc.ehu.es/sbweb/fisica_/dinamica/circular/circular/din_circular.html
- [2] ↑ S Gimeno Aribau. «Tesina sobre remodelación de vías ferroviarias».: http://upcommons.upc.edu/pfc/bitstream/2099.1/3336/5/34082-5.pdf
- [3] ↑ Ministerio de Fomento de España. «Apartado 4.3 Norma de trazado 3.I-C». Archivado desde el original el 27 de agosto de 2012. Consultado el 1 de mayo de 2013.: https://web.archive.org/web/20120827064130/http://www.carreteros.org/normativa/trazado/3_1ic/apartados/4_3.htm