Tram Paris (RATP – Paris Public Transport Operator), France

Rehabilitation of Concrete Track Slabs Under Extreme Time Constraints

As part of an ongoing maintenance program, concrete track slabs on tram lines T5 and T6 in Paris are being replaced under live operating conditions. The client is RATP. The works are carried out predominantly in dense urban environments, under traffic, under significant time pressure, and with no tolerance for delays.

Once the last tram leaves the section at night, a tightly scheduled work window begins. Approximately four hours are available before the first tram resumes operation early in the morning. Within this timeframe, power isolation, removal of the existing slab, installation of the new concrete, and subsequent cleaning are completed. Restricted site conditions, concurrent road traffic, and high requirements for safety and cleanliness define the execution.

The system used is Concretum^® Q-FLASH 2/20 in combination with CEM100 rapid hardening cement. This solution enables fast and reliable strength development, ensuring that the track can be reopened on schedule. Even under night-time construction conditions, the application remains stable and reproducible.

The workflow for each intervention is precisely defined: following demolition, the rapid-hardening concrete is placed within approximately 45 minutes, followed by curing and cleaning of the track surface. Just a few hours later, the line is fully operational again. Typical slab dimensions are approximately 1.30 m × 10.00 m × 0.21 m.

The project has been implemented as part of a multi-year program since 2026. For 2026, approximately 90 slabs are planned, of which 14 have already been completed and a further 16 are currently under construction (status as of April 2026). The result is a robust and scalable maintenance solution that ensures reliable daily operation even under the most demanding conditions.