Availability of digital infrastructure data
For a system-wide introduction of DAS-based energy efficient driving,
infrastructure data have to be supplied in a digital form, containing the exact
position of stops, junctions, curves and curve radii, slopes etc. In most
railway companies these data are only available on paper. Digital version may be
obtained by different methods:
- Manual data conversion: This method is very liable to mistake and proved
insufficient at DB AG (for the ESF project, cf. Example)
- Laser scanning of infrastructure: A special vehicle with a mounted laser
scanner “scans” the whole infrastructure. This method is very expensive (~ 2
million EURO for a country like Germany, France or Spain)
- GPS scanning of infrastructure: This method is cheaper and was applied in
Austria. However the result is less accurate compared to laser
scanning.
The digitalisation of infrastructure data is one of the principal bottlenecks
for the implementation of DAS systems in countries with a big railway network.
In smaller railways like SBB, a manual route-by-route approach is feasible.
Updating of track information
For the effectiveness and reliability of DAS recommendations, up-to-date
information on track conditions are crucial. If static track and timetable
information is used, temporary low-speed sections are not taken into
consideration and may lead to DAS causing additional delays. Dynamic information
could be supplied via an automatic update at stations (e.g. by a W-LAN link) or
via continuous updating by GSM (or other). At DB AG it is planned to make use of
the new electronic timetable method (EBuLa) as a data basis for the driving
advice system ESF (cf. Example).
Acceptance by drivers and management
Some drivers will be reluctant to follow the recommendations of a DAS for
several reasons:
- If drivers experience train delays caused by insufficient or wrong
infrastructure information in the DAS (e.g. temporary low-speed sections),
they will no longer follow the system’s recommendations.
- Some drivers may experience DAS as a step towards automatic train control
and therefore as a step towards losing their jobs.
- If drivers are not intensively familiarised with the DAS, many will not
understand the system and will take the recommendations as irrelevant
additional information.
Some decision makers think that acceptance by drivers puts too much
uncertainty to the effectiveness and thus payback of the system.
Delayed trains
The effectiveness of the system is reduced if train punctuality in the
network is low, since the DAS has no effect in this case.
Unexpected stops
If unexpected stops due to red signals occur on the trip, the DAS can no
longer operate or may even lead to additional delays. This cannot be avoided
even by up-to-date track data, but would require a permanent link to the
control centre being a future upgrade of DAS.
Computing power
DAS being a real-time-application, limitations of computing power installed
on-board may pose a problem in some cases. |