Introduction
The most basic definition of a railway is “a prepared track which so guides the
vehicles running on it that they cannot leave the track” (Lewis 2001). According to
this definition, railways were already used by the Greeks and Romans. However,
the concept of railway as we know it today—that is, rails made of iron, with trains
composed of several wagons pulled by one or more locomotives running on
specified timetables, forming nationwide or international networks—is an invention
of the early nineteenth century (Lewis 2001).
Since its inception, the technology of rails and trains has evolved considerably.
Two main forces have driven this evolution: the reduction of costs and the increase
in safety (Shabana et al. 2008; Flammini 2012; Profillidis 2014). The reduction of
costs has been achieved by increasing energy efficiency and, simultaneously,
increasing the speed and size of the trains. According to the International Energy
Agency and the International Union of Railways, from 1975 until 2012, the energy
used by passenger/km decreased by 62%, while the energy to transport cargo by
tonne-km decreased by 46% (Railway Handbook 2015). This increase in energy
efficiency was accompanied by a 60% reduction in CO 2 emissions for passenger
and 41% for freight transportation (Railway Handbook 2015). Three countries—
China, India, and Russia, with extensive railway networks, and where associated
environmental impacts are likely to be important—exemplify these achievements.
China boasts 60% (27,000 km) of the total high-speed lines in the world and has the
lowest rate of energy consumption per passenger-km (67 kJ/passenger-km). India
has the lowest CO 2 emissions per passenger-km (10 g CO 2 /passenger-km) and the
lowest rate of energy consumption per tonne of goods transported
(102 kJ/tonne-km). Russia has the lowest CO 2 emissions per tonne of goods
transported (9 g CO 2 /tonne-km) (Railway Handbook 2015).
Increases in railway safety have also been substantial, not only for passengers,
railway workers and freight, but also for the human populations living in the
vicinity of the railways (Shabana et al. 2008; Flammini 2012; Profillidis 2014). The
safety achieved in the railway sector is particularly impressive when compared to
road safety. According to a report by the European Railway Agency (2013), the
fatality risk in the period 2008–2010 measured as the number of fatalities per billion
passenger-km is 0.156 to railway passengers and 4.450 for car occupants. In fact,
following the same report, transport safety is only surpassed by the airline industry
with 0.101 fatalities per billion passenger-km.
Besides economic and safety advantages, there is general agreement that railways have several environmental advantages relative to roads. We highlight two of
them: Firstly, railways are less pollutant than roads because the metal-to-metal
contact characteristic of railways considerably reduces rolling resistance; thus, a
diesel-powered train is more energy efficient than the equivalent number of road
vehicles. In addition, an electric-powered train is not a source of direct emissions of
greenhouse gases and other air pollutants, and even indirect emissions can be
negligible when the electricity is cleanly produced (Chandra and Agarwal 2007;
4
L. Borda-de-Água et al.
The most basic definition of a railway is “a prepared track which so guides the
vehicles running on it that they cannot leave the track” (Lewis 2001). According to
this definition, railways were already used by the Greeks and Romans. However,
the concept of railway as we know it today—that is, rails made of iron, with trains
composed of several wagons pulled by one or more locomotives running on
specified timetables, forming nationwide or international networks—is an invention
of the early nineteenth century (Lewis 2001).
Since its inception, the technology of rails and trains has evolved considerably.
Two main forces have driven this evolution: the reduction of costs and the increase
in safety (Shabana et al. 2008; Flammini 2012; Profillidis 2014). The reduction of
costs has been achieved by increasing energy efficiency and, simultaneously,
increasing the speed and size of the trains. According to the International Energy
Agency and the International Union of Railways, from 1975 until 2012, the energy
used by passenger/km decreased by 62%, while the energy to transport cargo by
tonne-km decreased by 46% (Railway Handbook 2015). This increase in energy
efficiency was accompanied by a 60% reduction in CO 2 emissions for passenger
and 41% for freight transportation (Railway Handbook 2015). Three countries—
China, India, and Russia, with extensive railway networks, and where associated
environmental impacts are likely to be important—exemplify these achievements.
China boasts 60% (27,000 km) of the total high-speed lines in the world and has the
lowest rate of energy consumption per passenger-km (67 kJ/passenger-km). India
has the lowest CO 2 emissions per passenger-km (10 g CO 2 /passenger-km) and the
lowest rate of energy consumption per tonne of goods transported
(102 kJ/tonne-km). Russia has the lowest CO 2 emissions per tonne of goods
transported (9 g CO 2 /tonne-km) (Railway Handbook 2015).
Increases in railway safety have also been substantial, not only for passengers,
railway workers and freight, but also for the human populations living in the
vicinity of the railways (Shabana et al. 2008; Flammini 2012; Profillidis 2014). The
safety achieved in the railway sector is particularly impressive when compared to
road safety. According to a report by the European Railway Agency (2013), the
fatality risk in the period 2008–2010 measured as the number of fatalities per billion
passenger-km is 0.156 to railway passengers and 4.450 for car occupants. In fact,
following the same report, transport safety is only surpassed by the airline industry
with 0.101 fatalities per billion passenger-km.
Besides economic and safety advantages, there is general agreement that railways have several environmental advantages relative to roads. We highlight two of
them: Firstly, railways are less pollutant than roads because the metal-to-metal
contact characteristic of railways considerably reduces rolling resistance; thus, a
diesel-powered train is more energy efficient than the equivalent number of road
vehicles. In addition, an electric-powered train is not a source of direct emissions of
greenhouse gases and other air pollutants, and even indirect emissions can be
negligible when the electricity is cleanly produced (Chandra and Agarwal 2007;
4
L. Borda-de-Água et al.