STORY. Several tens of meters under the earth, four-hundred people will work twenty-four hours on twenty-four, and seven days a week, to renovate the 3.7 km of tracks of the RER line A. Details.
In this month of July 2017, those who come to visit the construction site of renovation of the RER A is first struck by the silence which reigns there (notwithstanding the noise and construction equipment). The Auber station, usually crowded, is almost empty. A few workers are at work. The docks are planed, and the rails occupied by containers of ballast used on one side, of a mechanical shovel mounted on wheels of the other. In teams, rotating, day and night until the 27th August next, 400 employees scurry to replace 3.7 km of track and four switches on a portion (The Defence-Châtelet) of the line’s most popular European – 308 million passengers in 2016. “These materials need to be replaced every forty years”, explains Philippe Martin, deputy general director in charge of transport operations and associated maintenance of the RATP.
Technically, the site is not difficult : it is to replace the tracks and the ballast. The tricky part is at the level of the logistics to be put in place. Judge for yourself. Seven-hundred and twenty new ties are laid each day, and 45,000 cubic metres of ballast will be put in motion over a month. Every day, seven trains take the old ballast and then bring something new.
On the RER A, the equivalent weight of fifteen Eiffel tower passes each day
These gravels, whose size and shape conform to a standard, are essential to the maintenance of the shape of the path. “Without the ballast, the rails do not stand even the passage of a single train, the path would be”, explains an expert from the RATP. “At the Auber station, we have calculated that this is equivalent to the weight of fifteen Eiffel tower happening every day.” The caillous which is formed in the ballast, by nesting one within the other and being compacted “to the millimeter”, allow the track to cash the shock without deformation. “When the ballast is too old, the rock breaks and erodes.” The elements fit so less well with each other and absorb less shock, hence, the need to change them regularly.
The old spans, tropical wood, raised in the 70s, will be replaced by concrete sleepers. It will not be so any more sensitive to humidity, which can be quite high in the tunnels of the RER A. “And the ecological impact in terms of deforestation will be limited”, explains a member of the RATP.
The line will be the subject of further instalments of work in the years to come. “By 2021, it is a 24 km of track and ballast, and 27 switches, which will be renewed between Nanterre-Préfecture and Vincennes”, we are advised by the RATP. The next campaign is planned, theoretically, in forty years.
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