For many UK holiday journeys, taking a train or coach instead of driving alone or flying can reduce estimated emissions per passenger. The size of the difference depends on the route, how full the car or service is, and which emissions a calculation includes; no single figure applies to every trip.
How large can the difference be?
The UK Department for Transport (DfT) illustrates the potential difference with an estimated London–Glasgow journey. Using 2023 conversion factors, it estimates these emissions per passenger:
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| Mode | Estimated emissions per passenger |
|---|---|
| Coach | 22 kg CO2e |
| Train | 28 kg CO2e |
| Average petrol car | 90 kg CO2e |
| Plane | 175 kg CO2e |
On this example, the petrol-car estimate is more than four times the coach estimate. These are DfT estimates for an illustrative UK journey, not measured emissions for a particular booking or a universal ratio for other routes. The DfT’s 2023 transport and environment statistics notes that circumstances on individual journeys can differ.
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A coach or train can carry many people while sharing the journey’s vehicle or service emissions among them. A car’s per-passenger result depends heavily on how many people are inside. In its methodology, the DfT adjusts car emissions using an average occupancy of 1.5 passengers, based on the National Travel Survey. A car carrying more people spreads its estimated emissions across more passengers; a solo driver does not.
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Rail results also depend on the service. The DfT’s train estimate uses a national rail factor that combines electric and diesel rail. A specific route or train may differ from that network average. Likewise, “coach” and “plane” figures describe estimated averages, not necessarily the exact vehicle or service a holidaymaker uses.
What the emissions estimates include
The DfT comparison includes direct emissions and indirect “well-to-tank” emissions for the modes. For aviation, it also adds a central estimate for indirect atmospheric effects, including contrails; the DfT says these effects are uncertain. A result can therefore change depending on the calculation’s boundaries, especially whether these aviation effects and access journeys are counted. See the DfT methodology and guidance for details of the comparison.
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Route and transfers can change the result
A whole-trip comparison should reflect the actual distance and legs involved, not just a mode’s emissions per kilometre. A less direct road journey, a drive to an airport, or rail and coach transfers add distance and emissions. Conversely, a direct ground route can compare well even if a simple per-kilometre average seems less favorable. The DfT’s Leeds–Belfast example illustrates the point: the car journey travels farther to reach a ferry terminal, which affects the mode comparison.
When planning a holiday, compare the door-to-door journeys you would actually take, including getting to and from stations, airports, or ferry terminals. Do not assume that a headline mode ranking captures those extra legs.
A historical UK comparison per passenger kilometre
Transport Scotland’s Carbon Account for Transport No. 10 reports these UK mode-level averages for 2018:
| Mode | Emissions per passenger kilometre |
|---|---|
| Average coach | 28 g CO2e |
| National rail | 44 g CO2e |
| Average petrol car | 122 g CO2e |
| Domestic flights | 158 g CO2e |
These are historical averages, not current predictions for an individual holiday itinerary. They are useful as a separate, broad comparison, but should not be combined directly with the DfT’s London–Glasgow whole-journey estimates: the figures cover different measures and years. The figures are published in Transport Scotland’s 2018 mode-efficiency comparison.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to compare your holiday options
- Compare the whole journey: Include the route’s actual distance, transfers, and travel to and from stations, airports, or terminals.
- Check car occupancy: A car shared by several people has a different per-person estimate from the average-occupancy assumption or a solo trip.
- Read the rail factor carefully: A national network average may not match the electric and diesel mix on a particular service.
- Check aviation boundaries: Find out whether airport access and indirect atmospheric effects are included; those effects are uncertain in the DfT comparison.
- Keep dates and measures distinct: A whole-journey estimate in kilograms is not interchangeable with an older average in grams per passenger kilometre.
For a UK holiday, the London–Glasgow example shows why coach and train travel can have a substantial estimated per-passenger advantage over flying or driving alone. Your own result depends on the itinerary and assumptions behind the estimate, so treat published comparisons as guides rather than guarantees.
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