A method determines a quality characteristic, in which the quality characteristic is representative for the procurement of a vehicle-specific friction coefficient of a vehicle and a standardized friction coefficient of a friction coefficient map. The friction coefficient data are received, the friction coefficient data being representative for a friction coefficient measured depending upon the position of a vehicle and a quality characteristic representative for the vehicle. The friction coefficient map is provided, the friction coefficient being representative for standardized friction coefficients of a vehicle fleet of a route network. Depending upon the friction coefficient data and the friction coefficient map, the quality characteristic is determined again and transmitted to the vehicle.