Page 400 - 360.revista de Alta Velocidad - Nº 6

Watson, Inara. Amer, Ali. Bayyati, Ali.

Consider Figure 4.1. there are clear differences in energy efficiency for different modes of
transportation, but the HSR seems to be the most efficient mode of transportation. HSR loses
its energy consumption benefit in comparison with air transport at speeds between 300 and
400 km/h, as the actual value depends on which route is considered and on the efficiency and
aerodynamics of trains and airplanes. Two main factors determine a train energy consumption;
namely, acceleration and overcoming rolling resistance. HSR is the more efficient transport
mode, even when compared with conventional railway. New high-speed trains have improved
design to reduce drag, increases capacity, and uses lighter materials that reduce the weight
of the train. The new articulated high-speed train AGV from Alstom has a reduced weight and
needs 15% less energy than that of TGV and has 98% recyclability (www.bombardier.com.).
Power output for high speed trains depends also on a train formation. Trains can have different
formations from 16 or eight cars as has Shinkansen Series 500 and Shinkansen Series 700 or
the 8 cars that Frecciarossa has. Some trains are more flexible in formation as AGV can be
formed from seven, eight, 10, 11 or 14 cars. Reducing the axle load is the most critical factor
to increase the speed of trains and reduce the energy consumption. This can be achieved by
introducing the articulated railcars, and using a new more lighter material. For TGV, Duplex
car bodies, aluminium was used which is easy to recycle and it does not lose its quality after
recycling. In order to increase the passenger-kilometres carried per unit of energy, there is a
need to consider the train length, so that instead of having locomotive and passenger cars,
these can be replaced by electric multi units.

Figure 4.2 Comparison of the net energy drawn from the line by the HS2 reference trail output for
the London-Birmingham baseline simulation with data for other high-speed trains
(Watson R., 2012)

Figure 4.2 demonstrates that the lowest energy consumption belongs to Shinkansen rolling
stock. One explanation for this is that in Japan rolling stock is renewed to a more efficient
type every 15-20 year. Newer high-speed rolling stock has improved the design, reduced drag,
increased capacity, reduced axel load, improved energy efficiency and upgraded passenger
comfort to meet changing customer expectation considering the fact that trains in Europe are
designed for 30-40 years’ service life.

398 360.revista de alta velocidad