References

Marmaray – CR1

D2S International is in charge of the noise and vibration studies for this project consisting of 64 km tracks from which 20 km at European side and 44 km at the Asian side. This study included a major noise and vibration measurement campaign in over 250 sites. In a second stage of this study, optimal protection is determined for sensitive areas and buildings, including noise screens and special measures for viaducts and stations.

Two new metro lines

Inside nearby buildings along two future metrolines for two different track fixation systems, based on numerical simulation of 8 sites located in the alignment. Comparison was carried out according to the local regulation.

GLT

The GLT is a guided light transport system with one central rail for guidance a rail fixation system on concrete has been designed.

RER Line D, crossovers

Two existing crossovers were installed on concrete beams on elastomeric under sleeper pads in rubber boots embedded in a concrete slab. A reduction in vibration and ground borne noise had to be achieved. Since the installation on floating slab had become practically impossible, a creative solution with damped vibration absorbers installed on the tunnel invert was implemented.

Metro extension Erasme – floating slabs for the crossovers

Design, follow-up during construction, performance measurements and evaluation.

Tramway line 55 – track fixation system

A direct rail fixation on concrete slab was designed. The selected system shows a good overall vibration isolation performance with a minimal rail deflection vibration levels are below the limit of 100 µm/s in the buildings and the rail displacement is always below 0.8 mm. The fixation system is simple (one base plate with one rail pad), non-expensive and easy to install. Furthermore, the rail is completely disconnected from the street pavement, so no degradation of the street/rail interface occurs. This latter problem is a major drawback for most existing embedded rail systems.

Leopold Railway Station

New trackwork was to be installed in this station, which is adjacent to the offices of the European Community. Since SNCB opted for ballasted tracks, a solution was designed with floating slabs (concrete U-shaped slabs on an elastomer mat) which were filled with ballast (4 tracks). The preparatory work included the computation of the first resonance frequencies of the complete system, the computation of the resonance frequencies of the wheel/rail/ballast system and the prediction of the vibration mitigation. Assistance was provided during the execution of the works. The system performs as designed.

D2S International was consultant to Eurotunnel for the evaluation of the different proposals from the contractor for the direct rail fixation system and contributed to the section of the specifications for the trackwork related to the dynamic characteristics. D2S International assisted with the testing of the dynamic characteristics of the selected system twin blocks with rubber boots without sleeper bar.

Metro lines 2 & 3 – Extension

Conceptual design of floating slabs for the crossovers of extensions of lines 2 and 3. Our mission also includes the follow-up during construction and the performance evaluation.

Floating slab for metro

Design and feasibility study of a floating slab for the metro passing under the New Acropolis Museum.

Fastener design

NYCTA wanted to reduce ground borne vibrations by 35 % and airborne noise by 10 %. They had determined that this required a fastener that was 35 % less stiff than their current fasteners (19 kN/mm). The fastener had to be a single unit for easy field installation that integrated their A-type rail plate and could only raise the top of rail by 28.5 mm. All this meant there was very little room to work with. The vibration damping material gives the fastener a very low stiffness of 12 kN/mm, which would result in very large displacements. To combat this and provide a stable track, the plates are pre-loaded so that the material still operates in its linear elastic range, but the additional vertical displacement during passage is minimized. The fastener went through 3 million cycles of vertical and lateral fatigue testing and is installed on an elevated structure and in a tunnel.

Paved track design for tramways

This study implied the development of a non expensive, stable rail fixation system for tramways which does not interact with the street pavement and which is performant in terms of vibration isolation. The design was successfully tested on the tramline at Bobigny.

RER tunnel les Halles – Gare du Nord

This is a concrete tunnel with heavy traffic and heavy axle loads. The existing Stedef track (twin block sleepers with rubber boot in concrete trackbed) was upgraded by introducing in the boots new vibration damping pads with alternating stiffness (DS-ISO-RAIL). The result is improved vibration isolation (gain of 3 to 5 dB) and better track stability (reduced static rail deflection).

Premetro

A single elastic rail fixation system (DS-ISO-RAIL) on a concrete slab was designed for all tunnels of the premetro system (about 10 km of tracks). The first tracks were installed before 1980. The latest section of 3 km was inaugurated in 1996. The system shows a perfect behaviour in terms of vibration isolation (not one complaint was received) and in terms of track maintenance. A similar rail fixation system was also installed on a 1 km tram track (Blancefloerlaan) outside the tunnels in order to verify the energy reduction of the system in comparison with a classical fastening system (project for the EC in 1988) a 5 % reduction in energy consumption was measured in favour of the DS-ISO-RAIL system.

Tramway chaussée de Charleroi

Design of a floating slab for a tramway line.

Tramway

Design and control of floating slabs and slabs on piles in highly sensitive areas.