The lock keepers, invisible little hands of the Seine

David Liouville, lock keepers in Port-à-l'Anglais manages the two locks and the dam from his computer screens.

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• Lock keepers are essential for navigation on the Seine.

  They allow boats to pass dams without hindrance

• On the lock barrage of Port-à-l'Anglais (Val-de-Marne), they pass between 50 and 80 boats every day

It is 1 p.m. this Thursday in October when David Liouville, 47, including twenty as a lock keeper, relieves his colleague at the Port-à-l'Anglais lock dam, in Alfortville (Val-de-Marne).

The man with the long hair sits in the 360-degree glass tower overlooking the dam and lock on the right bank.

From his post, "the lock keeper" as he prefers to call his profession, controls the locks on both banks.

He also manages the dam, takes care of filling and emptying the locks for the passage of boats, mainly freight.

“For locks, the time for cranks is long past.

There was the era of the buttons and since 2003, it is computerized, and everything is managed on computers, ”explains the former soldier, while the roadblock activates alone.

This has been computerized since the beginning of the year.

"I recorded the necessary settings and the dam operates autonomously," explains the employee of the Voies Navigables de France (VNF) public establishment, which manages this dam and the two 180-meter long locks.

Few relations with users

Never seated on his wheelchair, which he has taken care to put away in a corner, David Liouville spends his time standing behind the control post which has seven screens: three above his head to monitor, four on his desk , with a VHF radio to communicate with approaching boats.

If necessary, he goes to the foot of the lock in order to retrieve “floating” waste, this waste obstructing the entrance to the lock.

"Carnot for Port-à-l'Anglais!"

»: At 2:35 pm a voice comes out of the radio, breaking the calm of this early afternoon.

David immediately replies: "Port-à-anglais listen!"

At the end of the line, an empty boat wants to pass the lock to sail towards Paris.

Another ship has just left the right lock, so David directs the boatman towards it with a simple “right bank” pronounced in the radio.

To determine which lock to steer the approaching boat towards, David relies on the data transmitted to him by the boatmen as well as on his knowledge of boats used to passing through this lock.

He knows the lengths and widths of boats as well as their depth.

It is mainly this data which determines the lock to be used.

"There may be traffic jams"

From the top of his tower, David has to face the boatmen who are not always very cooperative: “Some people think that I am at their service.

While depending on the types of boat to pass, there can be traffic jams.

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Our dossier on the Seine

If the boatmen only guess the lock keepers by their voice, from their control tower, the lock keepers can see the boats passing by.

In the future, however, they may only see them through surveillance cameras, in a centralized control post.

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20 seconds of context

The series "The new course of the Seine" was produced by a promotion of nine work-study students from the Paris school of journalism ESJ-Pro, under the direction of their trainers and the 20 Minutes team.

The subjects paint the changing relationship between Paris and its river, the image of which is upset by the constant improvement in water quality.

• Environment

• Planet

• Boat

• Seine

• Barrage

• Paris