The importance of electrically insulated tracks

A high electrical insulation of the track infrastructure is an important aspect, especially for urban transport modes, such as for light rail and metros. If the railway system is not adequately insulated from the ground, this can lead to damaged tracks and pipes laid underground. Stray currents can cause considerable corrosive damages to the rails, fastening systems and installed track reinforcement. In addition malfunctions in train control and signalling systems are possible effects. Stray currents also lead to the risk of damaging surrounding rusted metallic components that are not part of the railway, such as gas pipes.

The standard EN 50122-2 specifies requirements for protective measures against the effects of stray currents caused by the operation of an electrically powered railway. The following aspects have a significant influence on electrical insulation and should be considered during the track design phase: distance of the substations, return line connections, insulation of the rails from earth and additional measures to improve them.

Often control and signalling technologies, such as train detectors, are in use on the infrastructure to detect and position vehicles, in order to secure the track. The use of such circuits results in specific insulation requirements for the track system. In order to ensure reliable train operation, construction measures must provide defined electrical and magnetic characteristics for track sections in which track circuits are to be installed.

In some cases, the planned slab track is designed with a reinforced in-situ concrete layer. The diameter of the reinforcement also has an influence on the control and signalling systems. Steel reinforcement in the track and track system, such as tie bars or lattice truss girders, dampens the electrical field. If an electrical conductor comes into the oscillating electrical field generated by induction, the frequency will change. For this reason, it is important to ensure a proper electrical insulation of the track system.

In general, a track system is ideally suited if it guarantees a high level of insulation, including a sufficiently large safety buffer to compensate for the difference between laboratory tests and the real condition on the track site.

EBS as safety buffer
The Corkelast® EBS-RF and EBS-UF track systems (EBS) are designed to match these high requirements. The key component of both systems is a prefabricated tray which consists of Geotextile and the Corkelast® elastomer. This material combination ensures a very high electrical insulation. The tray is working as an insulating intermediate layer and will disconnect fastening systems from the track as well as both running rails.

EBS: rail-to-rail and rail-to-earth insulation





Corkelast® ERS on new Botlek bridge

The new Botlek lift bridge over the Maas in the port of Rotterdam sets standards! It is the largest lifting mass in the world and offers the fastest lift/lower cycle. The bridge should have a lifespan of 100 years and must withstand 900.000 lifting operations without damage.

The new Botlek Bridge is a combined rail and road bridge that replaces the old Botlek Bridge, as part of a major renovation of the A15 motorway in the Netherlands.

This bridge is really a ‘steel chunk of superlatives’: Its two movable superstructures each have a span of 92 m and are around 50 m wide. Each of these monster parts weighs 4.850 t. Together they could practically outweigh the Eiffel Tower!

Such an impressive bridge deserves an impressive track system. We are proud to be involved in this project by providing technical advice, the track design, components and the installation of the double track. Our Corkelast® ERS Embedded Rail System was installed to attain the highest track availability.

The railway bridge is planned to be operational in Spring 2021. The construction consortium A-Lanes consists of John Laing, Strabag, Ballast Nedam and Strukton.

You may also be interested in: (free PDF handbook ERS on Bridges) (our Bridge Competence Centre)



EBA approval solid structure bridges

We are delighted to announce that The German Federal Railway Authority (EBA) granted edilon)(sedra GmbH Munich approval for the ERS-HR rail fastening on solid bridges.

This continuously elastic rail fastening system, which has been successful throughout Europe for over 40 years, is now also available in Germany up to a maximum speed of 160 km/h.

Reduction of construction height
The main field of application are short (semi-)framed structures up to approx. 25 m length with minimum construction height and demanding acoustic requirements. For this purpose, steel troughs will be integrated into the concrete slab, thus achieving a reduction in construction height of up to 70 cm. The embedding of the rails in a continuously supported elastic polymer is optimal in reducing acoustical emissions and thus is capable of reducing secondary noise emissions.

This was preceded by almost 10 years of operational testing on regional lines as well as on lines of the long-distance and conurbation network.

Technical support
The ERS fastening system is based on the Corkelast® LCS level crossing technology, which has already been successfully used for over 20 years in the network of Deutsche Bahn.

For more information please consult our technical ERS-HR bridge specialists. They are eager to answer your questions and offer you technical support!