In addition to our GWR passenger carbon calculator, which gives you indicative emissions for rail and car travel all over the UK, we monitor the energy use of our specific fleets and calculate our overall emissions every four weeks as part of our work to minimise our environmental impacts. We monitor our fuel efficiency, vehicle mileage and use of efficiency technologies, and report these to the Department for Transport.
We have estimated the carbon footprint of your train journey, and an alternative car journey, by multiplying together three pieces of information:
1. The number of passengers (the default is one)
2. The distance of your journey, per passenger. This data comes from WebTIS, the system we use for online ticket purchasing, which in turn takes distance information from the rail industry’s ‘National Routeing Guide’ data feed. The data describes the total distance of your journey, from station to station. If there are multiple route options for your journey, the distance is specific to the route you have selected. If you select a return journey, the travelling distance is set accordingly. For car travel, we don’t know the specific route you would travel, so to give an indicative comparison we have assumed you would travel the same distance by car as you would by train.
3. The average emissions intensity of rail and car travel for every km travelled, per passenger. We have used overall averages for UK rail and car travel, as published in the UK Government GHG Conversion Factors for Company Reporting, 2016. Car data is published per vehicle; to convert to ‘per passenger’ figures we used the national average car occupancy of 1.6 people, based on the Government’s National Travel Survey: England 2015.
Vehicles that are more energy efficient have lower emissions, and changing the type of energy (e.g. diesel, petrol and electricity) also affects emissions.
The GWR carbon calculator uses overall averages for the UK to produce simple, indicative results. These reflect the mix of vehicle types and fuels used across the UK, as described in the UK Government GHG Conversion Factors for Company Reporting (2016).
For national rail, the government data gives one overall average (it doesn’t distinguish among types of train). We use this data so that we can represent your journey no matter where you travel across the UK. In reality, emissions from diesel and electric trains will be different, and we are in the process of introducing new electric fleets across the GWR network. We are currently doing work to assess the carbon implications per passenger of this transition.
Season tickets can be purchased for periods of a week up to a year.
Based on our Customer Satisfaction Survey, we know that most people buying season tickets use them five days per week. If you buy a weekly season ticket, we therefore assume that you will use it for two journeys per day (outbound and return) on five days – a total of ten journeys.
If you buy a monthly or annual season ticket, we do the same but reduce the total number of journeys by an allowance for annual leave, to estimate a typical representative number of journeys and hence carbon footprint.
If some or all of your train journey has to be made by rail replacement bus, the carbon emissions will be higher than indicated by our GWR carbon calculator. Government data indicates that average local buses have around twice the carbon footprint per passenger compared to national rail, though this is still 13% lower than an average car.
The GWR carbon calculator is based on carbon footprint data for rail and car travel per person, given average numbers of passengers in each type of vehicle.
Overall, increasing passenger numbers in a vehicle will usually mean lower emissions per person and vice versa.
The effect will be smaller for public transport, including train travel, because one additional passenger is a relatively small addition to total passenger numbers (a small marginal change).
For example, the total capacity of trains ranges from around 200 to 850 passengers. Given this range, one additional passenger is just a 0.1-0.5% increase in occupancy. This is unlikely to change fuel efficiency (and hence total emissions) significantly, so one additional passenger would give something like a 0.1-0.5% reduction in the footprint allocated to each passenger. It’s therefore unlikely that one extra passenger (or one passenger less) will have any notable effect on the footprint per passenger.
The effect is more significant for cars, because of their lower capacities. If a car has one passenger to start with, adding an extra passenger doubles the occupancy but is unlikely to affect fuel efficiency significantly. Therefore, the footprint would be roughly halved per person – a large change. This is why car sharing is an important way to reduce the footprint per person of car travel, where car travel is unavoidable.
The government’s National Transport Survey (2015) shows that the average occupancy of cars is 1.6. To give simple, indicative results, the GWR calculator uses this average occupancy to calculate the footprint of car travel per person.
A carbon footprint is the total greenhouse gas emissions caused directly and indirectly by an organisation, product or activity, such as rail travel. Six different greenhouse gases are typically included and quantified in terms of equivalent amounts of carbon dioxide, hence the common term ‘carbon footprint’.
The Greenhouse Gas Protocol is a widely used family of standards for carbon footprinting. The GHG Protocol commonly separates emissions into three scopes. Scope 1 is the direct emissions from an activity; Scope 2 is indirect emissions from purchased electricity, steam, heating and cooling; and Scope 3 is all other indirect emissions. The table below gives examples of each of these for both rail and car travel.
Example sources of greenhouse gas emissions
Direct emissions from diesel locomotives
Direct emissions from the tailpipe of a petrol/diesel car
Generation of electricity for electric trains
Generation of electricity for electric cars
Manufacture of trains and rail infrastructure
Manufacture of cars and road infrastructure
A 2010 study from the RSSB estimated that scope 1 and 2 emissions from traction energy use represent the majority (63%) of the ‘whole-life’ carbon footprint of the rail industry in Great Britain. Including other forms of Scope 1 and 2 emissions (e.g. energy use in depots and stations) takes the figure to 81%, with the remainder represented by various types of scope 3 emission.
The GWR passenger carbon calculator uses independent government data to describe the Scope 1 and 2 emissions associated with national traction energy use (i.e. powering the trains). It therefore covers the majority of the emissions associated with average national rail travel in the Great Britain. The calculator compares these emissions with comparable (scope 1/2) emissions from travelling the same distance in an average car.
Our GWR carbon calculator gives you an indicative carbon footprint of travelling by rail compared to travelling by car. We compare only against one alternative option to keep the results concise, and we chose a car because this is the most widely representative alternative to UK train journeys. In some instances, other modes such as bus or air travel may be applicable. If you’d like to compare your journey with these alternatives, see the UK Government GHG Conversion Factors for Company Reporting.
GWR’s Sustainability Strategy is based around RSSB’s Sustainable Rail Principles. These principles represent the core values of the rail industry and are fundamental in delivering a sustainable railway that meets the needs of society without compromising future quality of life. The ‘Customer Driven’ element of the principles encourages the industry to embed a culture where customers are at the heart of decision making, and can make optimal travel and logistics choices. Within the Sustainability Strategy, GWR outlined a commitment to update its carbon calculator. GWR sees the provision of a carbon calculator as an essential tool to help our customers choose a low carbon mode of travel.
At the time of writing, GWR is the only train company to include carbon information in the booking flow, making it the most accessible information available. We are also going further than many in providing transparency over how the figures are calculated (through this FAQs section).