solutions to reduce the carbon footprint and the energy usage of
subsystems such as signalling where modern signal heads have the
size and weight of a television set in comparison with the larger and
heavier versions of the past. They also use LED technology with less
costly installation and maintenance requirements (How, 2012).
Driver Advisory Systems have the potential to significantly
reducing the traction energy consumption of vehicles. For instance,
these systems can provide accurate information to the driver in
terms of optimum speed profile allowing for the introduction of socalled
eco-driving approaches to the railway. They can also pave the
way to sophisticated timetabling and support for intelligent traffic
management systems.
5.4.2. Traffic management systems (TMS)
Traffic management systems are essential to the operation of
a railway. However, they are more than just running these operations
to a timetable (How, 2012). TMS can also facilitate a number of
tasks such as the ones listed below which have direct effect in the
amount of energy used:
Optimise traffic movements;
Inform timetable improvements;
Predict and resolve traffic perturbations over wide areas;
Help reduce wear and tear on infrastructure and rolling stock.
5.5. Innovative solutions: Energy Storage Systems (ESS)
Energy Storage Systems (ESS) have the potential to optimise the
energy usage of railways by either reducing the amount of energy
required to run them or reduce the energy losses (thermal) in the
form of regenerating the energy dissipated during braking (within
the same vehicle or sharing it with other vehicles in the systems via
the catenary). This is particularly true for on-board ESS.
There are a variety of ESS systems available each one of them
with their advantages and disadvantages. Specifically, railway
systems are investigating the use of the following types of ESS:
Battery technology;
Double-layer capacitors;
Flywheels;
Hydrostatic accumulators.
Multiple factors influence the choice of ESS for a specific
application. The methodology shown in Fig. 16 summarises a suitable
preliminary approach.
Hybridisation of power drives has a strong potential to signifi-
cantly reduce the energy consumed by railways as well as minimise
their impact on the environment. Urban and suburban operations
can maximise this potential due to the particularly favourable
operational conditions and duty cycles. For instance, they have
multiple short and frequent stops requiring sharp acceleration and
braking phases. Their track properties can also benefit hybridisation
e.g. metro systems have pronounced incline topography
between stations favouring coasting approaches.
Refer.