Railway Transport – Track & floating slab design

Istanbul (TR)

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.

Malaga (ES)

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.

Caen (FR)


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

Paris (FR)

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.

Brussels (BE)

Metro extension Erasme – floating slabs for the crossovers

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

Brussels (BE)

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.

Brussels (BE)

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.

Channel Tunnel Trackwork

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.

Chennai (IN)

Chennai project metro rail

Determination of track performance in a metro tunnel. Determination of insertion loss on different sections in the tunnel.

Athens (GR)

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.

Athens (GR)

Floating slab for metro

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

New York (US)

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.

Paris (FR)

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.

Paris (FR)

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).

Antwerp (BE)


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.

Brussels (BE)

Tramway chaussée de Charleroi

Design of a floating slab for a tramway line.

Bordeaux (FR)


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

Florence (FR)

Florence tram

Determination of track performance; comparison of two types of vibration mitigation measures (2 performance levels) with a reference track. Determination of insertion loss and own frequency.

Istanbul (TR)

Marmaray Bosphorus Crossing projects

D2S International is in charge of the noise and vibration design of the tracks for this project, consisting of 14 km tracks for passenger and freight trains, from which approximately 12 km of double track tunnels and underground stations passing in close vicinity of highly sensitive old historical walls and mosques.

Istanbul (TR)

Tramway of Eskisehir

General review of trackwork design with emphasis on vibration mitigation and drainage.

Pueblo, CO (US)

Transmission loss measurements on 5 track systems.

Namur (BE)

New HST station

The tracks had to be isolated from the rest of the concrete structure in order to prevent vibration transmission. D2S International designed an affordable floating track (ballasted track) which performs as requested.

Paris (FR)

Rail fixation system for ballasted track

This study implied the development of a rail fixation system on the wooden sleepers (embedded in ballast) in order to increase the vibration isolation performance of the ballasted metro track.

Zaventem (BE)

New HST Station

A study to determine the dynamic stiffness of the undersleeper pads (monobloc sleepers in concrete trackbed) was required to ensure correct vibration isolation from the track to the environment (Diamond Hall in airport building/Sheraton Hotel). The required acoustic absorption in the station hall was also determined in order to get an acceptable acoustic environment.

Brussels (BE)

Tunnel of Laeken

A new tramway tunnel was to be built under TV studios. Initially a floating slab was envisioned to protect the studio. The study which included on site analysis, including vibration impact tests in the tunnel, resulted in the design of double elastic rail fasteners (elastomer between rail and base plate and between base plate and concrete) on a concrete trackbed. These fasteners produce a very low wheel/rail first resonance frequency (and hence very good vibration isolation characteristics), combined with a low static rail displacement (through compression springs which generate a pre-load on the base plate) and hence good track stability. Vibration levels from rail operations cannot be measured in the studio. This excellent result was obtained at a fraction of the anticipated cost.

Brussels (BE)

Midi Station, HST

The aim was to obtain low noise levels (Lmax < 60 dB(A)) in the station hall (steel frame structure) during train passage. A detailed noise and vibration analysis of the station was performed. The study called for a track fixation system that significantly reduces the effects of ground borne noise. The design consists of a standard twin-block sleeper (as in ballasted track) on a resilient undersleeper pad in rubber boots. The boot design eliminates lateral friction between the surfaces of the sleeper blocks and the boots. The installed system produces excellent results and meets all requirements.