A unique new-generation OCS in southwestern France

A new milestone has been reached in the extensive overhead catenary system renovation project undertaken by ENGIE Ineo, agent of a consortium with Colas Rail, since the end of 2016 on the Toulouse to Bayonne railway. A second section of the new generation OCS* installed since September 2017 has now been activated by SNCF Réseau. Deployed for the first time on a line of this importance, this new technology, capable of withstanding a much stronger electric current, meets the requirements of the French government’s objectives concerning the restoration and modernisation of the country’s existing transportation network.

Complete replacement of 90-year-old catenary installations

Commissioned in the early 1920s on the stretch between Tarbes (Hautes-Pyrénées department) and Montréjeau (Haute-Garonne department), the first-generation catenary system, known as “Midi”, bore witness to the increasing obsolescence of the network in this region. The antiquated load-bearing cables and metal structures both complicated maintenance operations and compromised train schedules. By 2015, speeds on the line had to be reduced to 60 km/h in hot weather. Anticipating the growing difficulties, SNCF Réseau contracted with ENGIE Ineo and Colas Rail in 2016 to deploy a new overhead line technology on the stretch between Tarbes and Montréjeau.

Technology that is unique in France, for deployment on new railways

The specialists in electrification and railway signalling within ENGIE Ineo (agent of a consortium with Colas Rail) have been applying their expertise since December 2016 over these 53 km of the railway between Toulouse and Bayonne. The contract involves gradually replacing the first-generation “Midi” catenary system specific to the southwest of France with a reinforced OCS capable of supporting currents closer to the voltage generated on the LGV high-speed rail lines (25,000 volts).

The first railway line of this magnitude to accommodate this new technology, the section between Tarbes and Montréjeau will be equipped with a specific system currently deployed in the Paris region, on the RER B regional express line. This system will subsequently be installed on other lines of the French rail network.

Extensive human and railway resources mobilized since September 2017

The particularity of the project is that this railway line ensures the transportation of pilgrims to Lourdes on specially chartered trains that run every year from March to October. In order to avoid holding up the passage of these trains, the consortium’s teams developed a project comprising three phases. The first phase, initiated in September 2016, consisted in several months of preparatory work. The second phase began on 25 September 2017 and concerned a first stretch in the Haute-Pyrénées department of more than 13 km between Montréjeau and Lannemezan, activated on 21 December. This phase was completed on 1 February last with the activation of the second section of 4 km between Lannemezan and Capvern. Carried out within a very tight timeframe, sometimes involving up to 150 people on the worksites, the operations to remove the “Midi” catenary system and install the new-generation OCS required an extensive mobilization of resources. More than 1,700 catenary supports and 34 km of overhead lines were deployed. The last crucial phase is due to take place from September 2018 to early February 2019 between Capvern and Tarbes, representing a stretch of 30 km of double track.

“In order to install this new catenary system, we had to implement some rather unusual resources. These notably included catenary platforms and a concrete train, which had not been used for at least a decade. We are proud to contribute the expertise and skills of our teams to a project of this magnitude,” said Thaddee Pattyn, in charge of this project at ENGIE Ineo with Colas Rail.

* The ENGIE Ineo and Colas Rail teams are replacing the Cu-AC 150 mm² reinforced normal “Midi” catenary system with a CSRR (Caténaire Simple Régularisée Renforcée, reinforced regularized single catenary) TSI system.