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A perfect view of Paris

If you want to see how popular Crossrail will be when it opens, then it is worth taking a trip to Paris and going for a ride on the city's RER Ligne A.

Moving, moving, keep the trains moving." That is the mantra repeated by everyone at the Paris transport authority RATP when you ask them about their flagship route RER Ligne A. While in London we are edging towards starting to dig the first hole for our own mass transit, east-west rail crossing, in Paris theirs is at capacity and plans are being developed to expand its potential.

Click here to view a diagram of the RER Ligne A

The line connects suburbs and new towns to the east and west of the city direct with key points in the centre, from the business district at La Defense to the shops at Auber, to the commercial and retail centre at Chatelet Les Halles and the intercity staging point at Gare De Lyon. Crucially Ligne A links existing suburban railway by means of high capacity, limited stop, tunnel sections under Paris – just like Crossrail will do for London.

Since it’s opening in 1977 Ligne A on the Paris regional express network has proved a magnet to commuters. An impressive 1.2M of them now use it every day and the line carries 25% of all the suburban metropolitan traffic in Paris – a city of 11.5M people.

The RER was conceived back in 1962 in a smart piece of prescient planning – the same thinking that led the French to build nuclear power stations to guarantee power supply, and fund motorways by tolls while investing public money in high speed inter city train services – all infrastructure options that the UK is now looking at.

The route has already spawned a new metro line (Ligne 14) that mirrors its route and has acted as a pressure relief for Ligne A and four other RER routes that bring the capacity of the RER network up to 2.1M people a day. RATP and French National Railways SNCF jointly manage the route. SNCF looks after the suburban ends while RATP has the central section. RATP receives a fee of €3.5bn (£2.9bn) a year for its operation, to precisely quantified levels of service. Half the fee is accounted for by fares, the other half is funded by the public sector.

RATP and SNCF are also joint parents of signals specialist Systra which was part of the group that managed delivery of High Speed 1. The benefits to Paris of Ligne A, according to RATP operations director Patrick Buret, have been immense. "New towns have grown up around the route, housing 150,000 people. It has made new businesses possible," he says.

"It has made the French Canary Wharf at La Defense possible and the extra taxes paid there are enormous and on top of any anticipation in the original business case. The route has reduced traffic on the roads, pollution and travel times which are all of vital economic benefit to the city."

When Disney decided to build Disneyland Paris at Marne La Vallee it was a quick piece of investment to link the area into the Ligne A adding an entertainment aspect to the route’s economic benefit. "In the centre, the line is effectively a metro but in the suburbs it runs to a timetable as you would expect for main line trains," Buret says.

The timetable and the five branches of the line outside the centre – three to the west and two to the east – allow the high number of trains with remarkably short headways to storm through the central tunnelled section. Up to 30 trains an hour can run on that central section, each up to 225m long and carrying up to 2,000 passengers. This is thanks to an in cab signalling system called SACEM introduced back in 1989. Overlaid on the existing lineside system it uses two way track-train communication with Automatic Train Protection and Automatic Train Operation that allowed a 30% increase in train numbers.

Rather than relying on trackside signals, the train drivers receive messages in their cabs telling them what speed to travel, which allows trains to operate much closer together. "The train is a clever train and knows where the next train is," Buret says. In certain circumstances a following train can draw up as close as 2m to a train already in a station.

At peak hour RER Ligne A is supposed to be operating at 27 trains an hour. Growing passenger numbers are slowing things down however, and average peak operation is more like 24 trains an hour. Hence the focus on keeping the trains moving. Rolling stock is designed to start fast and brake fast. Doors open immediately when the train stops at a station, and drivers want to be away no more than 50 seconds later, but because of the sheer numbers of people getting on and off that has slowed to 60 seconds.

The solution is a £508M order for 30 new trains and 100 new carriages to replace the older, smaller capacity, rolling stock still operating on the line. These double deckers will all carry 2,000 people and are also designed so 25% of the length of each carriage is a door – 6m out of each 24m long carriage – which will help speed up passenger throughput. "That will give us an increased capacity of 40% or 12% to 14% extra passengers an hour. And that gives us 30 years of grace," Buret says.

But RATP is also looking to the future. Next up are plans for a metrophérique – an underground rail route circling round the suburbs of Paris, linking the metro termini and connect the burgeoning businesses and communities in the suburbs so people don’t have to travel through the centre to get to another part of the city. The timescale on that is between 10 and 20 years. If you are wondering what comes after Crossrail for London, this has to be a clue.

1977 - The year RER began operations

2003 - The last section opened (to Disneyland Paris)

107km - The length of the entire route

165 - Number of days in a year it carries over 1M passengers

6m - The width of the platforms

25% - Amount of Paris surburban metropolitan traffic it carries

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