Carbon Calculator

As well as using the indicative results from our carbon calculator, we monitor the energy use and fuel efficiency of all our trains. We calculate our overall emissions every four weeks and report back to the Department for Transport.

We estimate the carbon footprint of your train journey, and an alternative car journey, by multiplying together three bits of information:

1. The number of passengers

   This is normally one.
   
   

2. The distance of your journey, per passenger

   This comes from our online ticket system, which uses national rail data. If you choose a return journey, we just double the result.
   
   For car travel, we won't know the actual route, so we assume you would travel the same distance as you would by train.
   
   

3. The average emissions per passenger of rail and car travel per km.

   We use overall averages for UK rail and car travel, as published in the UK Government's 2016 GHG Conversion Factors for Company Reporting. To convert to ‘per passenger’ figures we use the national average car occupancy of 1.6 people, based on the Government’s 2015 National Travel Survey: England.

Vehicles that are more energy efficient have lower emissions. So, when you change the type of energy used, you will affect this.

Our calculator uses overall averages for the UK to give indicative results. This reflects the mix of vehicle types and fuels used across the UK, as shown in the Government's 2016 GHG Conversion Factors for Company Reporting.

For national rail, the data gives an overall average and doesn’t distinguish among types of train. In reality, emissions from diesel and electric trains are different, and most of our trains can now run on electricity. We are working to make sure our results reflect this.

Season tickets can be bought for periods of a week up to a year.

We know that most people who buy season tickets use them for five days a week. So, if you buy a weekly season ticket, we assume you'll use it twice a day (outbound and return) for five days. A total of 10 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.

If some or all of your journey is made by a replacement bus, the emissions will be higher than shown on our calculator. Data suggests that, on average, local buses have around twice the carbon footprint per passenger than national rail. Though this is still 13% lower than the average car.

Our calculator is based on carbon footprint data for rail and car travel, given the average number of passengers in each type of vehicle.

Overall, more passengers usually mean lower emissions per person and vice versa.

The effect will be smaller for public transport, which includes trains, because one extra passenger is a small change in total numbers.

For example, the capacity of trains ranges from around 200 to 850 passengers. Given this, one extra passenger represents just a 0.1-0.5% increase in occupancy, with a corresponding reduction in the footprint.

The effect is more significant for cars, because of their lower capacity. If a car has one person in it to start with, an extra passenger will double the occupancy but won't affect fuel efficiency significantly. Therefore, the footprint would be roughly halved per person. This is why sharing is an important way to reduce the footprint per person, where car travel can't be avoided.

The government’s 2015 National Transport Survey shows that the average occupancy of cars is 1.6. To keep things clear and simple, our calculator uses this figure to calculate the footprint of car travel per person.

A carbon footprint is the total direct or indirect greenhouse gas emissions from an organisation, product, or activity, such as rail travel.

Six different gases are normally included. They are quantified in terms of equivalent amounts of carbon dioxide. Hence the term ‘carbon footprint’.

The Greenhouse Gas Protocol is a widely used set of standards for carbon footprinting.
Emissions are split into three ‘Scopes’:

• scope 1 are the direct emissions from an activity
• scope 2 are indirect emissions from bought electricity, steam, heating and cooling
• scope 3 are all other indirect emissions

The table below gives examples of each of these for both rail and car travel.

Scope	Example sources of greenhouse gas emissions
	Rail travel	Car travel
Scope 1	Direct emissions from diesel locomotives	Direct emissions from the tailpipe of a petrol/diesel car
Scope 2	Generation of electricity for electric trains	Generation of electricity for electric cars
Scope 3	Manufacture of trains and rail infrastructure	Manufacture of cars and road infrastructure

A 2010 RSSB study estimated that Scope 1 and 2 emissions from traction energy use represented 63% of the ‘whole-life’ carbon footprint of rail in Great Britain. When other forms of Scope 1 and 2 emissions (e.g. energy use in depots and stations) are included, the figure is 81%. The rest is made of by various types of Scope 3 emissions.

Our calculator uses independent data to describe Scope 1 and 2 emissions associated with national traction energy use (i.e. powering the trains). It covers most of the emissions associated with average national rail travel in Great Britain. It compares these emissions with comparable Scope 1 and 2 emissions from an average car.

Our carbon calculator gives you an indication of carbon footprint of rail travel compared to that of the car. To keep results concise, we only compare against one alternative option. We chose the car because it is the most common alternative to the train. You can compare against other forms of transport here.

Our Sustainability Strategy is based around RSSB’s Sustainable Development Principles. These are key to delivering a railway that meets the needs of society without compromising the future quality of life.

In our strategy, we commit to keeping our calculator up to date. We see it as an important tool that will help our customers choose a low carbon mode of travel.