Braking Questions - Comparison between probabilistic mathematical safety margins calculations and operational data

The document DT 414 proposes a methodology based on Monte-Carlo algorithm to simulate the safety margins, represented by “k safety coefficients”, to be introduced in ERTMS guaranteed Emergency Braking Curve. In order to calibrate the results of this simulation the UIC Leaflet B 126-15C has analysed the statistical data of real recorders mounted on Rolling Stock in different Countries. Recording of train sets and locomotive hauled trains in Germany, Austria, Italy, France… have been analysed.

The experimental data have been compared with the result of simulation in the limited range of k coefficients 10^-2 to 10^-4 due to the limited number of samples. Generally the 2 k values, simulated and real are comparable eventually with a little adaptation of simulation input parameters.

The results encourage continuing such comparison to improve simulation realism. In this way it would be relevant to work particularly on the accuracy of recorder input parameters and the extension of data domain.