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Transport and Sustainability
Transport and Sustainability

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3 Is your journey really necessary?

The UK population has grown by about 30% since the early 1950s but transport energy demand has increased nearly fourfold. This growth is particularly a product of increased car travel, as shown in Figure 5.

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Figure 5: UK passenger transport by mode, 1952–2018
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This is an area chart showing the changes in UK passenger transport by different modes between 1952 and 2018. It is broken down into: rail, shown in green; a group consisting of buses and coaches, shown in yellow; pedal cycles, shown in grey; motorcycles, shown in red; a group consisting of cars, vans, and taxis, shown in light brown and then internal air travel, shown in blue. At the left it has a y-axis labelled ‘passenger kilometres in billions’, with a scale running from zero to 900. At the bottom is an x-axis, which runs from 1952 to 2018 and labelled ‘year’. Overall, there has been an enormous growth in passenger transport, the total number of passenger kilometres rising strongly from 220 billion in 1952 to about 400 billion in 1970 and on to 750 billion in 2000. After that, growth has slowed, only reaching 800 billion in 2018. The rail contribution is relatively small starting at 38 billion in 1952 and remaining at about that level until 1995 after which it has grown steadily to about 80 billion in 2018. The contribution from buses and coaches has a slow falling trend. It starts at 92 billion in 1952, falling to 60 billion in 1970 and to only 35 billion in 2018. The contribution from pedal cycles is small, starting at 23 billion in 1952, falling to only 4 billion in 1970 and only rising slightly to 5 billion in 2018. The contribution from motorcycles is also small, starting at 7 billion in 1952, falling to about 4 billion in 1970 and rising slightly to 5 billion in 2018. The contribution from cars, vans and taxis shows spectacular growth across the chart. It starts at 58 billion in 1952, rising to nearly 300 billion in 1970, nearly 590 billion in 1990 and 640 billion in 2000. The growth then slows to reach 670 billion in 2018. The contribution from internal air travel is small. It is virtually zero in 1952, growing to only 2 billion in 1970 and then to a peak of about 10 billion in 2005 before falling slightly to only 9 billion in 2018.

Figure 5: UK passenger transport by mode, 1952–2018

Reducing transport energy use raises a number of questions. The first is: ‘Is your journey really necessary?’ The ultimate energy service of transport is mobility; however, this is not quite the same as physical transportation.

Modern telecommunications offer a form of mobility. The Covid-19 pandemic severely limited the movement of people throughout 2020 and 2021. Lock-downs in many countries have changed patterns of energy use, with large numbers of people working from home. This resulted in large reductions in transport energy use, particularly aviation, and global oil consumption in 2020 was down 8% from its 2019 level. It has been replaced, in part, by extensive use of home working, reducing the amount of physical commuting, and by tele-conferencing over the Internet. It is difficult to say how much of the ‘physical transport habit’ has been permanently broken. In the UK, final transport energy use in 2023 was 7% down on its pre-COVID level in 2019. It is still possible that the world could return to its previous ‘business as usual’ state.

The next question is ‘Can your journey be done in a less energy (and CO2) intensive manner?’ Figure 6 compares the CO2 emissions of different modes of transport, both within the UK and for short international journeys to and from it. They vary enormously in their emissions per passenger-kilometre travelled. Air travel, for example, is both energy and CO2 intensive. International rail travel, between the UK and France through the Channel Tunnel, has the advantage of being both energy efficient and able to use low-carbon electricity.

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Figure 6: CO2 emissions of different modes of UK transport
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This is a chart of the carbon dioxide emissions per passenger kilometre for different modes of UK travel. It is a horizontal bar chart showing six modes of transport. The x-axis is labelled emissions in grams of carbon dioxide per passenger kilometre. The scale runs from zero to 200 grams. Reading downwards, the emissions for the six options are: UK average car, 172 grams of carbon dioxide per passenger kilometre; Air, short haul to and from the UK, 158 grams; UK sea ferry, 111 grams, UK average local bus, 104 grams; UK national rail, 41 grams and International rail to and from the UK by Eurostar, 6 grams.

Figure 6: CO2 emissions of different modes of UK transport

One social method to reduce the energy and CO2 intensity of travel is modal shift, i.e. moving journeys away from the energy-intensive modes and towards the more energy-frugal ones.

For policy purposes, modes of transport can be ranked in a hierarchy, with walking and cycling at the top and air travel at the bottom (see Figure 7).

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Figure 7: The low carbon hierarchy of transport modes
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This chart shows a set of seven horizontal bars stacked one above the other. The bars decrease in width from top to bottom and give the overall shape of an inverted pyramid. The topmost and widest bar is labelled ‘walking’ and has drawings of walking schoolchildren at left and right. The next, narrower, bar is labelled ‘cycling’ and has images of bicycles at the left and right. The next, narrower, bar is labelled ‘public transport’ and has an image of a bus at the left and a train at the right. The next, narrower, bar is labelled ‘taxi’ and has an image of a taxi at the left and right. The next, narrower, bar is labelled ‘pool car’ and has an image of a car at left and right. The next, narrower, bar is labelled ‘private car’ and has an image of a car at left and right. The lowest and narrowest bar is labelled ‘air’ and has an image of an aeroplane at the left and right.

Figure 7: The low carbon hierarchy of transport modes

For example, if a greater proportion of long-distance journeys within Europe were made by inter-city train rather than by air, the overall energy demand involved could be reduced substantially. In Sweden, an ‘anti-flying’ movement has arisen that has coined the word ‘flygskam’ (flying shame). Those who successfully shift to carrying out their journeys by train can indulge in a certain amount of ‘tågskryt’ (train bragging).

One particular target for improvement is the urban commuter who drives to work. The energy intensity could be significantly improved by making sure that cars contain more than just one person. Even better, the journey could be made by rail, bus or cycling.

The final question is, perhaps: ‘Does suburbia have a future?’ It may be necessary to create (and recreate) cities where it is not necessary to use a car to reach shops or schools, and they can be reached by walking or cycling.