RFF wants to select the route for the new line next year. Depending on the option chosen, it would be between 16 and 32km long and cost between Euros 1.4bn and 3.3bn to construct. RFF favours a route which serves Orly Airport directly with a station as close to the terminals as possible.

The new line will provide a direct link between Massy TGV station on TGV Atlantique and TGV Sud-Est and the TGV Interconnexion line running around the eastern side of Paris. At present trains must use conventional tracks, which is time consuming. Diverting TGVs on to a new line would not only reduce journey time but would also release capacity for RER and freight services.