I wrote this around 1996 while still at university. Hopefully, there are no major formatting errors. You will find references at the end. Enjoy!
1.
INTRODUCTION
"Transport is
a vital element in the economy of the country and the world. An
efficient and effective transport system is considered essential for
development and sustained growth." (Bruce Oelman, Statistics
Directorate, Department of Transport in Transport Statistics Great
Britain, 1994)
The above words
can mean different things to different people. What may be considered
efficient and effective by one group may be considered ineffective
and inefficient by another. Many have asked the question 'at what
cost?' And have gone on to question the need for the kind of
transport 'culture' that is to be found in many lands today.
In this discussion
the question of sustainability will be addressed, that is the ability
of the environment to continue to maintain its role as a
'life-support' system now, and into the future.
Energy use by the
major transport systems will be considered, as will the emissions
into the biosphere that reach the headlines when some begin having
breathing, or other health, problems. The longer term will not be
ignored, as the effect of transport on the projected greenhouse
effect will also be considered.
2. ENERGY
2.1
Manufacture
Before
any transport system can be manufactured, it is necessary to acquire
the raw materials.
As will be seen later, iron, steel and aluminium are major components
of modern transport systems. After extraction, the mineral-rich ore
has to be smelted. Both iron and aluminium occur as oxides, and
electrolysis is used, often after being treated with chemicals, to
separate the metal from the ore. This requires a great deal of
energy. For example, between 15 000 and 25 000 kWh for every tonne of
aluminium produced (Blunden and Reddish 1991), which is some 20 times
as much required to produce the same amount of iron.
Overall, transport
systems accounted for 33% of all energy used in 1993, an increase of
7% over the equivalent figures for 1983 (Transport Statistics Great
Britain 1994). In the eleven years referred to above, the energy
consumption for all users in the UK has risen by just under 11%,
whereas the energy used by transport rose by nearly 39%, the lion's
share, in terms of quantity of energy used, being consumed by road
transport (Transport statistics Great Britain 1994).
2.2
Operation
Any means of
transport requires energy to operate, this may be the metabolic
energy used by cyclists, or the chemical energy used by the world's
major transport systems. The amount of energy used, and the form in
which it is used, varies with the mode of transport concerned, and
has changed over time. Below, in table 2.1, are figures for the
energy consumed by transport operations in the United Kingdom for the
7 years, 1987 to 1993. It will be noticed that the energy consumption
by all transport systems has risen over 17% in those 7 years. The
greatest individual increase, in percentage terms, has been water
transport, which has risen by 22.8%, then aviation, at 22.3%, then
road transport, which has has risen by nearly 17%, whereas the energy
consumed by rail transport has dropped by nearly 6%.
Perhaps of greater
interest than the simple increase in energy use experienced by most
transport modes is the difference between the largest user, road
transport, and the railways, which uses the least. In 1993, road
transport used over 41 times as much energy as did the railways, and
some five times more than the next largest user, airways.
Table
2.1 Energy consumption 1987 - 1993: by transport mode.
|
106 Therms
|
|||||||
|
Transport
|
1987
|
1988
|
1989
|
1990
|
1991
|
1992
|
1993
|
|
Road
|
13 522
|
14 384
|
15 002
|
15 409
|
15 298
|
15 627
|
15,785
|
|
Rail
|
408
|
416
|
388
|
389
|
395
|
408
|
384
|
|
Water
|
438
|
460
|
538
|
541
|
565
|
546
|
538
|
|
Air
|
2 572
|
2 741
|
2 901
|
2 911
|
2 728
|
2 952
|
3 146
|
|
Total
|
16 940
|
18 002
|
18 834
|
19 250
|
18 987
|
19 533
|
19 853
|
Source: Department
of Trade and Industry. Adapted from Transport Statistics Great
Britain. 1994. HMSO. London.
It may be true to
say that an individual road vehicle uses less energy than an airplane
or train, but to arrive at a more meaningful idea of efficiency we
need to compare energy use with people or freight carried. There can
be some difficulties in using either people or freight, and
individual vehicles vary in energy consumed. However, table 2.2,
below, shows the approximate energy consumption per passenger
kilometre.
The list in table
2.2 is by no means exhaustive, but it is clear from this measure of
efficiency that cycling is the most energy efficient mode of
transport, and a typically loaded car in the greater than two litre
category is the least efficient. If only the motorised forms of
transport are considered, then a fully loaded double decker bus is
the most efficient. However, if we consider the typical loadings then
electric and diesel trains are the most efficient.
Table
2.2 Energy efficiency by transport mode.
|
MJ/passenger km
|
|||
|
Transport
|
Maximum loading
|
Typical loading
|
|
|
Cycle
|
0.09
|
||
|
Motorcycle
|
1.50
|
2.44
|
|
|
Plane (Boeing 737)
|
2.34
|
3.90
|
|
|
Single decker bus
|
0.47
|
1.38
|
|
|
Double decker bus
|
0.25
|
0.81
|
|
|
Electric train
|
0.38
|
0.69
|
|
|
Diesel train
|
0.50
|
0.69
|
|
|
Intercity 225 (electric)
|
0.59
|
1.00
|
|
|
Petrol car <1.4 litre
|
1.03
|
2.75
|
|
|
Petrol car >2 litre
|
1.88
|
4.94
|
|
|
Diesel car <1.4 litre
|
0.88
|
2.38
|
|
|
Diesel car >2 litre
|
1.47
|
3.94
|
|
Source: adapted
from Blunden and Reddish (1991).
Some 86% of all
passenger transport is in cars (Blunden and Reddish 1991), and it can
be seen from table 2.2 that there is a large difference between the
energy efficiency of a car loaded to capacity, and a car with typical
loading. In a brief survey of the number of occupants in cars, I
found that about 66% of cars had only one occupant (the driver), and
about 91% had one or two occupants, which was about 80% of all
traffic. Only about 3% of cars were running to capacity - that is had
four or more occupants.
As we are so
reliant upon cars for transport it is perhaps appropriate to consider
their current and potential efficiency at this point. It is usual in
Britain to assess the efficiency of a car by considering how many
miles per gallon (mpg) can be achieved. The average fuel consumption
for petrol driven four wheeled cars was 29.7 mpg over the 1991/93
period, and for diesel cars was 41.2 mpg (National travel survey, in
Transport Statistics Great Britain 1994). There have been
improvements in fuel efficiency in recent years, but most of this
efficiency has gone into producing faster cars, rather than producing
cars that use less fuel. The current best as far as efficiency is
concerned is about 55 mpg, whereas the number of new cars in the UK
capable of exceeding 120 mph trebled in the 1980s (Blunden and
Reddish 1991).
The world mileage
record, in 1988, was 6 049 mpg, achieved in the Shell Mileage
Marathon, with a vehicle of very low performance! It should be
possible, however, to use the lessons learned from this exercise to
produce a car with an efficiency of 200-300 mpg (Blunden and Reddish
1991).
Table 2.3
indicates the increasing reliance upon cars and vans for personal
transport. While the number of passenger kilometres remained
reasonably stable on the railways over the 11 years indicated, the
proportion travelling by train dropped, and the number of movements
by air increased, but the proportion remained stable.
It is no surprise
to see an increase in energy use when there has been, as indicated
above, a swing toward the use of the least energy efficient system.
Since 1975 the distance travelled per person on foot has gone down by
15%, the distance cycled has gone down by 24%, and the most energy
efficient form of motorised passenger transport, the bus, has
experienced a drop of 38% for local journeys, while distances per
person travelled by private cars has increased by 55% (Transport
statistics Great Britain 1994).
Table
2.3 Passenger transport by mode - selected years, 1983, 1988
and 1993.
|
109 Passenger
kilometres/percent
|
||||||
|
Transport
|
1983
|
%
|
1988
|
%
|
1993
|
%
|
|
Buses and coaches
|
48
|
9
|
46
|
7
|
42
|
6
|
|
Cars and vans
|
411
|
80
|
536
|
84
|
577
|
86
|
|
Motor cycles
|
9
|
2
|
6
|
1
|
5
|
1
|
|
Pedal cycles
|
6
|
1
|
5
|
1
|
5
|
1
|
|
All Road
|
474
|
93
|
593
|
93
|
629
|
94
|
|
Rail
|
34
|
7
|
41
|
6
|
37
|
5
|
|
Air
|
3
|
1
|
5
|
1
|
5
|
1
|
Figures for
percent are to the nearest 1%. Source: Transport Statistics Great
Britain 1994. London: HMSO.
2.3
Disposal
A lot of energy is
locked up in vehicles and infrastructure. Perhaps the area of
greatest concern is the disposal of cars, as these represent the
greatest proportion of energy, and raw materials, consumed by
transport industries.
At present about
77% of materials are recovered from cars, but no energy is directly
recovered, although by reusing materials, energy is effectively saved
by reducing the need for the refinement of new raw materials. It is
expected that this figure can be increased to 82% by 2015, with about
13% locked up energy being recovered directly (ENDS report 277.
1993). An increasing amount of plastic is used in the manufacture of
vehicles, and any that cannot be reused directly can be incinerated
to generate heat and electricity. Plastics have a relatively high
calorific value, typically about 35 MJ per kilogram, which is greater
than coal (The British Plastics Federation 1994).
2.4
Summary
As has been seen,
transportation of all kinds is energy hungry. Road transport is
particularly so, and it is this area that has witnessed the greatest
growth, with the more efficient systems (bus and train) either
declining in popularity or remaining static.
3. RESOURCES
3.1
Raw material acquisition and manufacture
In the UK alone,
there was an average of about two million new cars registered each
year over the period 1983 to 1993, along with a yearly average of
some 45 thousand goods vehicles and about 7 thousand buses, coaches
and taxis (Dennis 1995). All these new vehicles require raw materials
for manufacture, and have to be transported to the dealer or customer
for final distribution.
Transport
industries in the developed countries use 30% of all iron and steel,
23% of all aluminium and, with the advent of catalytic converters,
some 41% of all platinum (Blunden and Reddish 1991). The extraction
of these minerals has considerable impact on the environment. The
preferred method is open-pit extraction, which, as its name suggests,
involves working a wide area of exposed rock. This method is
economically very favourable as large earth moving machines can be
brought into use, but it is also one of the most environmentally
destructive methods used (Blunden and Reddish 1991). There are other
ways of extracting the ore, such as underground mining which, while
not as impacting on the environment as open-pit extraction, still
have considerable effects.
The smelting
process produces waste in the form of slag, and often chemical
residues as well. This waste used to be emptied into a tailings pond,
which caused a lot of environmental concern, but this problem has
been improved.
3.2
Construction of infrastructure
Infrastructure;
roads, railway lines, airports and sea ports, require great
quantities of aggregates, and other materials for their construction.
For example, one kilometre of six-lane motorway requires an average
of 62 500 tonnes of aggregates to build it, which is enough to build
about 1 250 three-bedroom houses! (Blunden and Reddish 1991) In 1986,
the UK produced 229 million tonnes of aggregates - an increase of
154% from 1957 (Blunden and Reddish 1991). The extraction of
aggregates has significant environmental consequences, the majority
in the UK being quarried. Underground mining has less environmental
impact, but only 0.5% of material is produced by this method in the
UK (Blunden and Reddish). The problems of quarrying include dust
being blown off site and the destruction of visual and amenity
interest in the area being worked. Because the residents of urban
areas do not like to have such disruption too close to them, there
has been a move toward quarrying at greater distances from urban
centres, often in places that are close to, or in, Areas of
Outstanding Natural Beauty, or National Parks, such as the Mendip
region of Somerset, the Craven district of North Yorkshire, the
Brecon Beacons of South Wales and the Charnwood Forest district of
Leicestershire (Blunden and Reddish 1991).
Most of the above
sites service the south-east of England, which means that the
extracted materials have to be transported over greater distances
than if they were quarried closer to their end user, requiring large
lorries that have their own environmental impacts. Whenever possible,
aggregates are extracted as close to the end users as possible to
reduce the costs of transport. This has had a great impact on the
landscape, and is likely to continue to do so. In 1993 the then
Environment Secretary, John Gummer, said "it will become
increasingly difficult to identify extraction sites which are
environmentally acceptable" (quoted in Nuttall 1993). At this
time a number of proposals were put forward that would involve the
development of Sites of Special Scientific Interest (SSSI), for
example, the company Alfred McAlpine Quarry Products intended to
reclaim its right to extract minerals from 476 acres (192.6 hectares)
in Dyfed, Wales, which includes Carmel Wood and a nearby bog, both
areas of scientific and environmental interest (Nuttall 1993).
3.3
Summary
As has been seen
above, the extraction of materials for infrastructure and vehicle
manufacture exacts a toll on the environment. This may be little more
than a nuisance, or it may destroy areas of scenic and scientific
interest.
4. HEALTH AND
THE ENVIRONMENT
4.1
Environmental degradation
All forms of
transport impact on the environment. Even walking and cycling have an
impact in that infrastructure is provided for their use. For example,
footpaths and cycle routes occupy land and, as has been seen earlier,
require raw materials and energy in their construction. These two
means of transport, however, are generally considered to have the
least impact, and for this reason, the environmental effects of the
various motorised transport systems will be discussed now. Below are
the major environmental impacts of these modes of transport (adapted
from Banister and Button 1993).
Rail: Railways
affect land resources by taking land for track, terminals, and other
infrastructure, sometimes partitioning farmland and wildlife
habitats, or causing the destruction of neighbourhoods if these
happen to be in the way of a line or terminal that is considered to
be of 'national importance'. Those living close to railway lines
often complain of noise and vibration, especially if the trains run
all night. In addition, when equipment, lines or rolling stock are no
longer required, they may be abandoned to lie derelict. Deaths of
humans result from collisions and other accidents.
Road: The
environmental effect of road transport that is seen most often in the
media is that of air pollution. This may be of two types, local
pollution and global pollution. Local pollution takes the form of
carbon monoxide, nitrous oxides, hydrocarbons, lead and particulate
emissions, which affect the quality of the air breathed in by people
on a local basis. This particularly affects those with health
problems living in urban areas. This subject, along with the next,
will be expanded upon in a later section.
Global air
pollution is that brought about by the emission of carbon dioxide and
other 'greenhouse gasses', along with chlorofluorocarbons and other
chlorinated hydrocarbons that affect the ozone layer, either as
byproducts of the internal combustion engine, or during the
manufacturing process. Water pollution may arise from water running
off the road surfaces, or by water systems being modified by road
building. Land is required for roads and other facilities, which may
go through areas of scientific or scenic interest, and may also
result in the demolition of dwellings. Old oil and abandoned vehicles
and rubble from construction works can have an effect on the quality
of the environment. Noise can be a problem for those living close to
busy roads, and many people and animals are killed each year by
vehicles.
Air: Pollution of
the air is similar to that for road transport above. Land is taken
for the construction of airports and service roads, which can affect
the environment in a similar way to that of roads. Noise can be a
problem, as can congestion around airports, and a number of people
are killed most years.
Water: This
transport system may result in the modification of waterways and
seaways to take modern ships. Land is taken for the construction of
ports, and pollution of the sea can be a problem when oil tankers run
into trouble, or when a ship's crew illegally wash out fuel storage
tanks at sea. Although serious accidents do occur, they are
relatively infrequent.
4.2
Toxic emissions
"...A city
gasping for breath under a suffocating blanket of toxic
pollutants..." (Read 1995)
You could be
forgiven for thinking that the above words came from a writer living
during the worst times of the industrial revolution. In fact it is a
description of one day (10th. October 1995) in Paris, France. On this
day the public transport systems had come to a halt, the result of a
public sector strike. Knowing this, people went into the city by car,
many leaving early to beat the rush, only to be brought to a
standstill by traffic jams. The situation was compounded by the
weather conditions of high temperatures with little or no wind, which
helped the nitrogen dioxide levels to increase rapidly. It was
estimated that, on this day, 80% of this increase was due to car
pollution (Read 1995).
In the high
temperatures of the internal combustion engine, atmospheric
dinitrogen readily combines with dioxygen to produce nitric oxide
(NO) or nitrogen dioxide (NO2). Nitrogen dioxide is an irritant, that
can prove dangerous to susceptible people. It is a constituent of
photochemical smog - the problem highlighted in the quote at the
beginning of this section. Further reactions can occur, for example,
the nitric oxide can, in the presence of molecular oxygen or ozone
and water, produce nitric acid, one possible component of acid rain
(O'Neill 1993).
The effects of
acid rain were first recognised in Scandinavia, where lakes were
found to be 'dying' - losing fish and other aquatic organisms. This
was attributed to increasing acidity brought about by rain polluted
by sulphur and nitrogen oxides. It has since been recognised that
lakes in the UK, especially South-West Scotland have also been
affected (Harrison 1992). In table 4.1 are figures for the amount of
nitrogen oxides released into the atmosphere according to transport
mode. As can be seen, the largest contributor is road transport,
which accounts for over ten times as much as the next largest
contributor - shipping.
Over the five
years referred to in table 4.1 the total amount of NOx emitted
by all transport sources rose by 8%. This is in contrast to all other
sources, which experienced a drop of 10% over the same period, and in
1992, transport accounted for 61% of all NOx emissions
(Transport Statistics Great Britain 1994).
Table 4.1
Transport nitrogen oxides emissions 1988 - 1992: by mode of
transport.
|
Nitrogen oxides:
|
103 tonnes of
nitrogen dioxide equivalent
|
||||
|
Transport
|
1988
|
1989
|
1990
|
1991
|
1992
|
|
Road
|
1 360
|
1 480
|
1 490
|
1 510
|
1 460
|
|
Rail
|
50
|
40
|
50
|
50
|
50
|
|
Civil aircraft
|
20
|
20
|
30
|
20
|
30
|
|
Shipping
|
110
|
130
|
140
|
140
|
140
|
|
Total all transport
|
1 540
|
1 680
|
1 700
|
1 720
|
1 670
|
The figures are
rounded to the nearest 10 000, therefore, totals may not appear to
equal the sum of their parts. Source: Department of Trade and
Industry. Adapted from Transport Statistics Great Britain. 1994.
HMSO, London.
In addition to the
foregoing, there are other pollutants of concern, namely, carbon
monoxide (CO), lead, smoke and particulates, carbon dioxide (CO2),
ozone (O3), sulphur dioxide (SO2) and volatile
organic compounds (VOC). In the case of carbon monoxide, there has
been an increase of about 2.5% in the five years 1988 to 1992, with
road transport being responsible for 90% of all emissions.
Non-transport sources accounted for 9%, the other 1% being shared by
the other transport modes (Transport Statistics Great Britain 1994).
Lead (Pb) is a
petrol additive that has given cause for concern because of its
poisonous effects. Lead is a cumulative poison, being stored by the
body in the bones. The effects of lead on the body are wide ranging,
including impaired blood synthesis, hypertension, hyperactivity and
brain damage (O'Neill 1993), and it is for this reason that there has
been a move toward lead-free petrol. It is often said that by the
government increasing taxes on leaded petrol they are encouraging the
use of the lead-free alternative (see for example Bannister and
Button 1993), but it is more likely that the increasing sales of
unleaded petrol is due to the availability of cars capable of using
it. In fact cars fitted with catalytic converters have no option but
to use unleaded petrol as the lead interferes with the action of the
catalyst. Of course, most people would prefer to spend as little as
possible, but if their car is unable to use unleaded fuel, they have
no option, if they want to continue using their vehicles, but to use
leaded petrol. Since 1983 the amount of lead released into the
environment by road transport has been going down each year, with the
figure of 1.7 x 103 tonnes emitted for 1992 being
about one quarter that of 1983 (Transport statistics Great Britain,
1994). This has been helped by the introduction of unleaded petrol,
but the largest contributor has been the gradual reduction of lead in
leaded petrol.
Ozone is a
secondary product in the troposphere that occurs naturally at very
low levels. As ozone is poisonous to plants and can cause respiratory
problems in people, it is not desirable to elevate the levels found
naturally (O'Neill 1993). This is in contrast to stratospheric ozone,
that is instrumental in protecting the earth from harmful
ultra-violet radiation. Ozone is a constituent of photochemical smog
(from Harrison 1992).
Ozone tends to be
in equilibrium with nitrogen dioxide and nitrous oxide, and if an
increase in ground level ozone is experienced it is likely that this
is a result of high levels of these nitrous oxides (Harrison 1992).
As both ozone and nitrogen dioxide are problematic to the
environment, it would be preferable if the levels were kept at a
'safe' level. Below, in table 4.2, is the classification of air
quality as it relates to nitrogen dioxide, ozone and sulphur dioxide
according to the Department of the Environment.
Table 4.2
Department of the Environment air quality classification.
|
Concentration range ppb
|
|||
|
NO2
|
O3
|
SO2
|
|
|
Very good
|
0-50
|
0-50
|
0-60
|
|
Good
|
50-100
|
50-100
|
60-125
|
|
Poor
|
100-300
|
100-200
|
125-500
|
|
Very poor
|
300
|
200
|
500
|
Source: Harrison
1992
Sulphur dioxide
emissions can result in bronchitis and other respiratory diseases,
and is a major contributor to acid rain. Transport accounts for about
5% of all emissions, with diesel fuel being more important than
petrol (Banister and Button 1993). The most important source of this
pollutant is coal-fired electricity generation, which has
environmental implications with respect to vehicle manufacture and
electrically driven rail transport (Banister and Button 1993).
Small particulate
matter stems from a number of sources, the majority of which are
transport related. These are generally referred to as PM10s, being
particles of 10 micrometers or less in size. They may come from wear
and tear of brakes and tyres, but the major source is engine
combustion, especially from diesel engines (Banister and Button
1993).
These particulates
may be themselves harmful, or they may carry toxic substances on
their surface into the small airways of the lungs (Banister and
Button 1993). These particles can impair lung function, and have been
associated with an increase in asthmatic attacks (Friends of the
Earth, 1994). At present the World Health Organisation (WHO) has not
set a 'safe' limit for exposure to PM10s, and a recent American study
has suggested that if particulate levels reach 50 micrograms per
cubic metre there will be, on average, four extra deaths per million
people over a three day period, with about an extra 1 400 extra
asthmatics needing their inhalers and six more requiring hospital
treatment. This figure, of 50 micrograms per cubic metre, is
exceeded, on average in the UK, on about 40 days a year, with the
highest figure in 1993 being 163 micrograms per cubic metre (Edwards,
1995).
All new cars
manufactured today are required to be fitted with catalytic
converters, which can mitigate some of the problems outlined above.
As their name suggests, Harmful emissions are converted into harmless
substances in the presence of a catalyst, a mixture of metals
including platinum and palladium, and metal oxides, such as chromium
oxide (O'Neill 1993). The harmful carbon monoxide, nitrous oxides and
hydrocarbons are converted into atmospheric dinitrogen, carbon
dioxide and water. Whilst this may be a step in the right direction,
it does not make a car 'environmentally friendly'. The World's
resources are still being consumed, and as we shall see in the next
section, carbon dioxide, while not being directly toxic, has its own
environmental problems.
Another pollutant
of concern is benzene, an aromatic hydrocarbon that has been shown to
be a carcinogen. It has especially been linked to leukaemia. The
World Health Organisation (WHO) has said that "no safe level for
airborne benzene can be recommended" (quoted in Friends of the
Earth, 1990). WHO also stated that "at an air concentration of
one microgram of benzene per cubic metre, the estimated lifetime risk
of leukaemia is four per million" (quoted in Friends of the
Earth, 1990). Air is the main route of entry into the body for
benzene, and road vehicles account for about 80% of benzene in the
air. The level of airborne benzene can be reduced by about 90% if a
three-way regulated catalytic converter is fitted (Friends of the
Earth, 1990).
4.3
Carbon dioxide
The concept of
global warming has been an environmental issue that has captured the
attention of the media during the latter part of the 1980s to the
present. It is commonly referred to as the 'greenhouse effect'
because it is generally thought that certain gasses in the atmosphere
allow shorter-wavelength electromagnetic radiation to pass through,
but absorb longer-wavelength radiation. As the radiation is of
longer-wavelengths at lower temperatures, the radiation reradiated
from the Earth's surface is of longer-wavelength than that entering
the atmosphere (O'Neill 1993). It should at this point be said that
this is a natural system, and without it the Earth would be much
colder than at present, and probably too cold to support life as we
know it. The greenhouse effect being referred to here is that
produced by anthropogenic sources, adding to the natural system. Many
gases are implicated in global warming, among them being methane,
chlorofluorocarbons and carbon dioxide (O'Neill, 1993). Here, it is
carbon dioxide (CO2) that will be the centre of attention,
not because it is the most efficient 'greenhouse gas' (methane is
much more efficient), but because it is amongst the most abundant,
and as such has the potential for a greater effect on the Earth's
climate.
There has been an
increase in carbon emissions from all transport modes, but the
greatest increase, and the greatest quantity emitted, has come from
road transport, which has shown an increase of nearly 27% from 1984
to 1992. The total emissions from all transport modes in the UK,
nearly 1.4 x 108 tonnes in 1992, represented 25% of
all emissions. During this period the emissions from all sources
other than transport dropped by nearly 0.6%. The projected total
carbon dioxide emissions for the UK are expected to grow by about 38%
by the year 2020, during this period emissions from transport sources
alone are expected to increase by about 70%, compared with 30% for
other sources (Transport Statistics Great Britain, 1994). As the
above figures illustrate, transport systems, and especially road
transport, are significant contributors to the levels of atmospheric
carbon dioxide.
It has been
estimated that a 5 kilometre trip by car releases about 0.96
kilograms of carbon dioxide into the atmosphere (of course, this
figure will vary with engine type and condition), which translates
into about 0.24 kilograms of carbon dioxide per person if four people
travel together, which, as has been seen earlier, is a relatively
rare occurrence. A full bus releases about 0.09 kilograms per person,
and a full suburban train about 0.04 kilograms per person (Holman,
1991). It is clear from these figures that the least efficient (from
the point of view of carbon dioxide emissions) method of transport is
a car carrying just one person (the driver), whereas the the best is
a full suburban train, closely followed by a full bus. Note that for
peak efficiency the train and bus need to be full, and that the level
of emissions (of all types) will depend on (in the case of the bus)
the type and condition of the engine, or (in the case of the train)
the method of electricity production.
4.4
Noise
Noise is
considered by many to be little more than a nuisance, affecting the
quality of life, rather than the health of the individual, or the
environment. Whilst this may be largely true, it can have effects
that go beyond the nuisance value. Excessive noise can lead to loss
of sleep, which in turn can lead to psychological problems and
physiological disorders such as stress and even cardiovascular
disease (Banister and Button, 1993).
The main problem
areas are along major roads, rail lines and locations such as
airports. Throughout the industrial world it has been estimated that
about 110 million people are exposed to noise levels exceeding 65
dB(A), which is considered unacceptable in OECD countries (Banister
and Button, 1993). As far as the UK is concerned, it is usually the
airports that draw the most attention with respect to noise, and
there was, for example, a population of about 53 thousand affected by
similar noise levels from Heathrow airport in 1991, with nearly 430
thousand being affected by lower, but still, significant noise levels
(Transport Statistics Great Britain, 1994).
4.5
Summary
From the above, we
can see that all transport systems impact on the environment, and can
be detrimental to the health of people, particularly those, such as
asthmatics, who are vulnerable to airborne pollutants. All transport
systems occupy land and require a power source, both of which impact
on the environment. We have seen that the major contributor to local
pollution is road transport, especially the private motor car. It is
this system that is also the main transport source of carbon dioxide,
which is considered to be an important contributor to global warming.
5. CONCLUSIONS
There are ways
that transport systems impact on the environment, and those living
within the environment, that have not been covered in this discussion
due to lack of space. Perhaps chief amongst these would be the death
toll of people and animals in collisions and other accidents.
If we consider
what has been covered, raw material acquisition, energy consumption,
land use and emissions, it is clear that the major consumer of raw
materials, land and energy is road transport, especially cars. It is
also clear that road transport is responsible for the majority of
emissions by a considerable margin.
If this is so, is
it all doom and gloom, or is there anything being done to address the
problem? If, as was said at the outset, 'transport is a vital element
in the economy of the country and the world' (Bruce Oelman,
Statistics Directorate, Department of Transport in Transport
Statistics Great Britain, 1994) no government is going to stop people
and goods being transported from place to place. What has been
suggested, however, is that there should be a change of emphasis
coupled with a reduced demand.
When travelling by
sea or air there are no viable alternatives, it is only on land,
where most travelling takes place, that there is a choice of
transport mode.
In order to reduce
carbon dioxide levels to 1990 levels by the year 2000, a study
conducted on behalf of the Department of Transport and the Department
of the Environment put forward the following as guidelines: 1. Reduce
overall travel demand, 2. Use more emission-efficient modes of
travel, and 3. Change the emission efficiency of transport (Ecotec
Research and Consulting Ltd., 1993). It has been found that the
travel demand increases rapidly as the population density falls below
15 persons per hectare, and that demand falls sharply as the
population density increases above 50 persons per hectare, therefore,
it would appear that the dispersal of populations from major centres
has increased the demand for transport, if this could be reversed
then the first of the guidelines above could be accomplished (Ecotec
Research and Consulting Ltd., 1993). Both rail and bus provide more
energy- and emission-efficient modes of transport than the private
car, but they do not attract the levels of use that the car does.
Cost is one factor that influences choice in this matter. An example
of this was recorded in the journal Rail. This involved the transport
of a repaired Intercity HST power car from Crewe to Plymouth, a
distance of about 250 miles. It was decided to make this transfer by
road rather than rail because of the time and costs involved - it was
estimated that it could have cost as much as 6 000 pounds by rail,
compared with an estimate of 1 800 pounds by road (Rail 1995). It was
pointed out in this article that the road journey was subsidised, for
example, police escorts from seven forces were used, paid for by the
tax payer. In a recent study it was suggested that cars and lorries
cost Britain 50 billion pounds a year in pollution, congestion and
accidents, about three times the sum collected in road taxes (Clover
1995). This would also suggest that road transport is subsidised. If
the subsidy levels were reversed, it may be that the second of the
guidelines above could be achieved. The third of the guidelines above
could be achieved by improving engine and fuel efficiency, by
limiting the maximum power output of vehicles, by improving vehicle
maintenance and by limiting maximum speeds (Ecotec Research and
Consulting Ltd., 1993).
Other measures
that have been proposed include establishing car-free zones and
pedestrian-only areas to encourage people to use public transport. It
has been shown that stricter emission testing and the introduction of
catalytic converters has improved air quality, and Steven Norris, the
Junior Transport Minister said "that by 2005 we will see carbon
monoxide levels falling by 65 percent, volatile organic compounds
including benzene falling by 86 percent and oxides of nitrogen by 66
percent" (quoted in Nuttall, 1995). This, unfortunately, does
not address the problem of carbon dioxide. This can only be achieved
by reducing the overall consumption of fossil fuels. However, despite
the problems and the need to travel, the technology is available to
reduce the environmental impact of transport systems, all it needs
now is the will of the transport using people.
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