Climate change

Why calculate the greenhouse gas emissions resulting from your transport?

The transport sector, together with the building sector, is the largest contributor of greenhouse gas emissions in France as well as Europe. In these two sectors, everyone’s behaviour can influence trends and help fight climate change.

By choosing RATP public transport, you’re opting to use five times less energy and emit 10 times less greenhouse gas on average than when you’re using your car.

How are travelling distances calculated?

Distances travelled are calculated according to the means of transport:
- by bus: distances known to the RATP services,
- by train: distance as the crow flies (radial distance),
- by individual car: radial distances adjusted according to a multiplying factor of 1.2.

For journeys by public transport, the total distances are calculated by adding the radial distances between each stage of the journey. For instance, an itinerary that includes a distance on foot, metro and bus, the calculated distance will be the total of each segment.

How are the calculations made?

By car, the distance covered corresponds to the total length of the journey.
Greenhouse gas emissions by car = total distance covered x average emission factor of a car in an urban environment.

For public transport, each segment is taken individually, and the emissions added at the end.
For instance, for the detailed journey in the diagram below, the calculation will be:
Greenhouse gas emissions by public transport = distance travelled by underground x average emission factor of underground trains + distance travelled by bus x average emission factor of a bus. Walking and riding a bicycle are not emitting factors.

In 2009, RATP assessed the total amount of greenhouse gases emitted as a result of its activities. This inventory included direct emissions (e.g. burning of fossil fuels or leaking of greenhouse gases from air conditioning systems) as well as indirect emissions (use of products whose manufacture generated emissions, emissions from staff travel, etc.).

The assessment showed that two thirds of the company’s greenhouse gas emissions came from energy use inherent in its activities (operation of vehicles, stations, workshops and buildings).

Promoting energy efficiency is therefore a key element in RATP’s action against climate change. Most of the improvements in results to date have been achieved in this area. As yet, only a small proportion of emissions reductions has been achieved by use of alternatives to oil and gas.
Similarly, the replacement of fossil fuels with alternative energy sources in both buses (electric cells, biofuels) and buildings (solar, geothermal) only accounts for a small part of the reductions achieved. However, in the longer term, it should have a significant impact on greenhouse gas emissions.

The modes of transport operated by RATP emit less carbon dioxide than private cars. In 2008, they avoided 2.2 million equivalent tonnes of CO2 emissions. Each RATP customer is therefore contributing to the fight against climate change.

In 2009, RATP conducted a study to assess carbon emissions generated by a passenger travelling one kilometre on its various transport services, based on the amount of energy used by RATP in 2008. The results showed that:

• Emissions from rail transport (metro, RER) are fifty times lower than those from private cars;
• Buses are “only” twice as environmentally friendly as cars in terms of carbon emissions. The improvement of the bus network must therefore be a priority.

Buses account for approximately 75% of greenhouse gas emissions from energy use. Three alternative energy sources are emerging to reduce the environmental impact of buses:

• Electric buses: RATP has pioneered this technology in its “Montmartrobus” electric minibuses, which have been used for the last 10 years in Paris’s Montmartre district. However, electric technology is not yet available for standard buses;
• Hybrid buses (electric/diesel): RATP will be putting hybrid vehicles on the road in 2011, once their performance levels have been tested;
• Biofuels: some RATP buses currently run on first-generation biofuels. In order to prepare for the future, RATP is supporting projects to produce second- and third-generation biofuels.

Use of renewable energy sources in our buildings and stations is another important area for action. Geothermal energy, heat pumps and photovoltaic panels are all systematically studied, evaluated and used on all new building or site modernisation projects.