FRENCH engineering groups Travaux de Sud Ouest and Société Européenne de Travaux Ferroviaires last month completed laying ballastless track through the 7·8 km tunnel that will carry TGV Méditerranée on the approaches to Marseille, using a new design of vibration-absorbing twin-block sleeper developed by Sateba.

The SAT S312NAT design has two conventional concrete blocks connected by a metal spacer, but the lower part of each block is encased in a rigid shell of synthetic material. This supports an anti-vibration pad on the bottom of the sleeper, to act as an insulating layer between the sleeper and the concrete track base.

By permanently attaching the insulating pads to the sleeper, the new design will speed up future replacements, minimising possession times. In addition, the rigid shell prevents deformation of the sheath during the casting of the track base concrete. It is also designed to prevent water ingress between the sleeper block and the pad.

Over 29000 sleepers have been laid in the Marseille tunnel, which will give Sateba practical experience with the design ahead of seeking export orders. During the tracklaying process, the rails and sleepers are installed, levelled and aligned by TSO, after which ETF is responsible for laying the infill concrete. Despite the high levels of accuracy needed, installation rates have averaged 200m per day.

Sateba, France

Reader Enquiry Number 138

CAPTION: French National Railways has approved a range of prefabricated drawing and connection pits for lineside cable and optic fibre installations. Legrand’s modular units are made from reinforced concrete, with interlocking catches each end to avoid the need for seals. Pre-cut knock-out sections allow for flexible assembly. Pits are built up from 200mm deep units, with a galvanised steel ring with rebates on the top to hold the cover slabs. The rebates are angled to avoid any jamming, and allow for the covers to be locked if necessary.

Legrand, France Reader Enquiry Number 144