Important task of railway traction vehicles is to achieve maximal tractive effort at any conditions if required. For this purpose the vehicles have slip controllers. Some types of these controllers need the vehicle longitudinal velocity value as an input. The vehicle longitudinal velocity is difficult to measure directly because the vehicle longitudinal velocity could not be directly determined from wheel velocity. When the wheel is driven its velocity is higher than the vehicle longitudinal velocity because of the slip phenomenon. The paper describes method that provides possibility to estimate the vehicle velocity on base of measured wheel velocity. Estimation of the vehicle longitudinal velocity is enabled by Kalman filtration. The method is verified by MatLab simulation using real measured data.