Apart from the barriers for DAS in general described in detail in DAS for
main line operation, in freight operation additional hurdles arise:
Unscheduled stops
In mixed networks, freight trains are frequently confronted with "train
conflicts" due to higher priority of passenger trains. Such incidents make an
effective use of DAS impossible. Therefore, as long as no link to control
centres is realised, the applicability of DAS for freight operation is limited
to situations with low traffic density or dedicated freight lines.
Variability of vehicle data
Whereas in passenger operation the vehicle mass and aerodynamics remain
virtually constant (as long as train configuration is left unchanged), the mass
and running properties of freight trains are subject to frequent changes: cars
are added or removed from the train, cars are filled or emptied at freight
centres etc. This leads to a high variability of train dynamics. However, these
dynamics are a vital input for DAS calculations.
At DB AG a tool has been developed to solve this problem. "ESF Lok" is an
on-board tool to determine the vehicle dynamics in real-time. ESF Lok calculates
the running resistance and the mass from the acceleration the train shows as a
reaction to an applied traction force. The acceleration is determined by GPS and
odometer and the traction force is measured by the locomotive. However, the
latter feature is provided only by certain locomotives, such as the series 101
at DB AG. It is not clear whether such a system can be generalised to all
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