TRANSPoRT PolICY STATEMENT: 09/03
In January 2009 the Government The long lead times required for such projects align
with Government targets for a more sustainable
announced that it is creating an national energy mix; new services could by then
organisation called High Speed be capable of supporting maximum speeds up
Two. The company is to consider to 320kph (200mph) without additional carbon
penalty. However, we believe that the energy
the case for new high speed services targets are extremely challenging. In the event of
from london to Scotland and to these targets not being achieved we recommend
develop a proposal for an entirely that line speed should be restricted to maintain a
sensible balance between shorter journey times
new line between london and the and reducing emissions.
West Midlands. IMechE welcomes
this announcement and considers In summary, the Institution:
high speed rail a central part of • Supports the construction of High Speed Two
but believes it is only likely to deliver significant
future transport policy and climate carbon reductions if our electricity supply mix
change mitigation. decarbonises considerably. If our energy targets
are not achieved, line speed should be limited
Encouraging modal shift should be a core tenet of until our grid mix is sufficiently sustainable to
a more environmentally sustainable UK transport deliver the climate change mitigation we aspire to;
policy. By reducing inter-city journey times, high • Advocates a new pricing model that reviews
speed rail has the potential to provide a realistic of the cost of tickets across all modes of travel.
alternative to other more carbon intensive modes Ticket prices should reflect the actual carbon
of travel. However, we should be realistic about impact of each journey and thereby incentivises
the potential carbon saving this may achieve. At less polluting forms of travel;
speeds above 160kph (100mph), much more energy is
• We don’t forget our existing infrastructure.
required to overcome air resistance and so the faster
High Speed Two is decades away. In the
we go the less the environmental benefits are.
meantime, we recommend that investment should
be focussed on achieving higher average speeds
to reduce journey times on the existing network.
This is best done by smoothing out the speed
profile and removing bottlenecks rather than
developing a number of short, fast stages.
Improving the world through engineering
HIGH SPEED RAIl
THE CuRRENT STATE oF THE RAIlWAYS THE ADvANTAGES oF HIGH SPEED
Rail usage has increased considerably in the UK over • low emissions. Using the same loading
the past 10 years with 50% more passengers and 40% factors, emissions from high speed rail compare
more freight1. This increase has been accommodated favourably, particularly for journeys over 200km
by incremental improvements to the existing (125miles). The exceptions are conventional rail
network such as the West Coast and Thameslink and coach travel where emissions are marginally
upgrades. However, further growth of 22.5% and less5. If new systems were electric, then emissions
30% for passengers and freight respectively is attributable to rail would reduce as a more
forecast by 20142. Despite these improvements, the sustainable and renewable national energy mix
existing network is therefore currently under severe was introduced.
strain and this situation is only likely to get worse.
Regardless of whether we pursue high speed or not,
the UK will need more rail capacity. Coach
Our existing network is far behind many of our
European counterparts. With one or two exceptions Rail – Electric
such as the West Coast and Great Western lines,
UK passenger services are limited by maximum
track speeds of 160kph. Despite this, many of our Rail – Diesel
newer trains are capable of speeds up to 200kph
(125mph). The upgrading of other key inter-city
lines would go a long way in reducing times and Rail – High Speed
accommodating any significant passenger growth.
Put simply, our technology is being restricted by
our existing network. Car
0 50 100 150 200 250
grams per passenger km
Figure 1: Average CO 2 emissions by transport mode
Source: WS Atkins, “Because Transport
Matters – High Speed Rail” 2007
• Direct city centre access. London to Glasgow by
In late 2008, the Government established a conventional rail takes five and half hours point
National Networks Strategy Group and announced to point. By air, typical journey times, including
an acceleration of work to develop a sustainable check-in, security screen and city centre transfers,
transport system, including high speed rail. are three and three quarter hours. Whole journey
Indeed, in January 2009 the Government times by high speed rail could be as low as two
announced High Speed Two, a company and three quarter hours – far quicker than air
established to look into high speed rail in the UK. travel and car or coach6.
But we are already much of Europe and the rest
of the developed world. Japan led with the bullet • High frequency of departures. Cab-based
train in 1964 with most large industrial countries signalling on high speed trains will allow a higher
following suit. There are now 3,480 miles of frequency of service whilst maintaining safety.
high speed lines in France, Germany, Belgium Trains will “know” the position and speed of
and Spain with a further 2,160 miles under trains in front of them and thus will not require
construction and another 5,280 miles planned. the current 7½ mile gaps between services.
China, Taiwan and Korea also have high speed • Extra capacity for both passenger and freight.
systems and one is about to be constructed in the This would allow extra rail services by releasing
United States. The UK has just 70 miles of high capacity on existing lines and help ease crowding
speed rail3. on inter-urban rail journeys. This will not only
increase passenger capacity but also have potential
High Speed Rail in the UK is not a new concept. In freight benefits. However, a high speed line would
2001 a study by WS Atkins4 examined options for not alleviate the gauge problems experienced by
improving existing East and West coast routes to freight operators on the current network.
the North, based on the high speed technologies • Improved links to key international gateways.
used in France. The MAGLEV contactless power Any new high speed line should only be considered
transfer system was also considered but with if it were to be linked to our existing international
issues such as lack of compatibility with other gateways, including Heathrow and St Pancras.
high speed lines, sustainability, cost and the fact
that it is still in the development stages, was not
considered to be a viable alternative. The study
presented its recommendations in 2003, concluding
that there was a strong business and transport
case for a range of high speed rail options.
THE DISADvANTAGES oF HIGH SPEED The faster a train moves the more energy it requires.
As Table 1 shows, energy consumption increases
• Price. Inter-city rail prices do not compare with speed and the performance of a train running at
favourably with low cost airfares particularly on 300kph (186 mph) uses more than twice the amount
routes such as London – Edinburgh or Glasgow of energy than a train travelling at 200kph, with only
with airline costs going down and rail costs rising7. a resultant 50% increase in speed. Indeed, to achieve
450 kph (280 mph), a train would require 5 times
• limited routes. Road and air transport tend to more energy than an equivalent running at 200 kph.
better link multiple routes, whereas high speed
links tend to only link a small number of cities in a However even at the higher speeds the there is
linear fashion. considerable environmental gain over other forms
• Rolling resistance. At 200kph 70% of the energy of transport. As total journey time is an important
required is used in overcoming wind resistance. factor for passengers there is a strong case for
This factor goes up with the square of the speed selecting a speed that competes with air travel and
and is over 90% at 350kph (220mph). Put simply, accepting the higher energy use. The Rail Safety and
the faster you go the more energy you need. Standards Board estimates that using the 200kph
• Possibility of no net emission reduction. There model a saving of up to 140 gCO2/passenger/km
is a risk that the introduction of high speed rail could be made for each passenger switching from air
may stimulate demand for travel and therefore to high speed rail9.
generate additional emissions. People may decide
that longer distance commuting is more feasible
and any move from conventional rail to high speed Speed v Time
would increase emissions. Further, the emissions
Energy consumption kWh/seat
Speed v Time
benefit of high speed is entirely dependent our
electricity mix (power/weight ratios mean that 3.0 60
electric power is a practical requirement for speeds
Journey time h
over 200kph). Currently, the UK’s centralised
generation capacity is very carbon intensive.
HoW FAST SHoulD HIGH SPEED BE?
Currently the Department for Transport defines
high speed as over 240 kph (150 mph)8. In general, Speed v Energy
UK passenger services operate at a maximum speed
of 160 kph with a mix of diesel and electric power
with inter-city services on the West Coast mainline
capable of 200kph. Examples of modern high speed 1.5 30
200 250 300 350
trains operated in Japan and Europe can travel at
over 320kph, although average speeds tend to be Speed limit km/h
less. If we were to undertake building a high speed Figure 2: Relationship between Energy, Speed and Time
line, how fast should we go?
Running trains at 320kph would be no problem if the
There are those that argue we should go as fast as we energy used was from a sustainable and renewable
can. However, is this sensible? Indeed, Maglev has source. However, UK energy supply is anything
been touted, which currently runs at speeds of up to but. Indeed, the carbon footprint of the national
430 kph (268 mph) in Shanghai. Maglev should not be electricity grid has actually risen in recent years to
considered not only because of the cost but because it 562gCO2/KWh in 200610. Unless we significantly
would require a completely new railway system that decarbonise our electricity supply, the environmental
would not be compatible with existing infrastructure. benefits of high speed are almost nonexistent.
A balance between speed – and therefore journey Fortunately, infrastructure development on such a
time – and emissions has to be found. large scale takes a number of years.
Speed (kph) 160 200 225 270 300 330 450
Speed (mph, rounded) 100 125 140 168 186 205 280
Energy Consumption 0.64 1 1.27 1.82 2.25 2.72 5.06
Table 1: Energy and power use coefficients for
different speeds, compared to 200 kph
Transport Statistics Great Britain 2008
• The Institution supports the construction of 2
DfT, Delivering a Sustainable Railway, July 2007
High Speed Two but believes it is only likely 3
to deliver significant carbon reductions if our DfT Britain’s Transport Structure –
High Speed Two, January 2009
electricity supply mix decarbonises considerably. 4
Atkins “Because Transport Matters – High Speed Rail” 2007
We consider that new services should be capable 5
of supporting speeds up to 320 kph (averaging EU Study – Competition between air and
High Speed Rail, November 2007
200–240kph). The timescale for infrastructure 6
development is such that the UK’s sustainable 7
energy mix should have improved sufficiently 8
by then to allow these higher speeds without DfT Britain’s Transport Structure –
High Speed Two, January 2009
additional emissions. If our energy targets are 9
RSSB Report “The case for rail 2007. The first
not achieved, line speed should be limited until sustainable development review of the mainline
our grid mix is sufficiently ‘green’ to deliver the railways of Great Britain” 25/06/07
climate change mitigation we aspire to; 10
DEFRA carbon emissions reporting guidelines –
• However high speed should be accompanied electricity conversion factors.
by a new ticketing model that reviews of the
cost of travel across all modes of travel. Ticket
prices should reflect the actual carbon impact
of each journey and thereby incentivise less
polluting forms of travel;
• But we mustn’t forget our existing
infrastructure. High Speed Two is decades away.
In the meantime, we recommend that investment
should be focussed on achieving higher average
speeds to reduce journey times on the existing
network. This is best done by smoothing out the
speed profile and removing bottlenecks rather
than developing a number of short, fast stages.
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