Composites Putting UK Trams on Track for Cost Savings

As part of the Low Impact Light Rail initiative, funded by innovate UK, UK Tram has appointed a research team comprising specialists from Atkins, Brecknell Willis and Cecence to look at adapting composite materials for use in overhead line equipment used to supply power to the trams. Stage one of the research project involves the development of a viable gantry design, with the main aim of reducing the whole life cost of these kinds of structure.

Using layers made up from compounds such as carbon bound together using a tough resin are being increasingly used in

Paul Hooper from Atkins said:

We believe that there is potential to significantly reduce the costs of overhead line systems by utilising advanced composites in the support structures as an alternative to traditional metallic structures. Additionally these materials have the potential to reduce the amount of equipment required and can be readily shaped to blend into the environment and thereby reduce the visual impact.

For this project the group will support the copper ‘contact wire’ from a high tensioned carbon-fibre reinforced plastic catenary cable. The cable itself would also be supported by glass-fibre reinforced plastic poles and support cantilevers.

Glass-fibre reinforced plastics are electrically insulating and the carbon fibre reinforced plastic does not expand or contract as the temperature changes. Due to these properties the proposed new design will mean the spacing between pylons can be increased by approximately 40% which would therefore require fewer poles and less cable tensioning equipment. It would also eliminate the need for electrical isolation and reduce the amount of electrical bonding required.

The glass-fibre is also more resistant to corrosion, meaning that it will last longer and be less subject to environmental damage and thereby cheaper to maintain. As a result it is believed that inspection and maintenance will only be required every 15 years, rather than every five. The anticipated life of the pylons will also increase with replacements required approximately every 40 years rather than every 25. Although elements of the proposed design are more expensive than existing options, the estimated cost savings for the project are substantial, ranging from £50k-£100k per kilometre for a typical track where pylons are used. A similar cumulative maintenance saving is also expected after seven years of operation.

Paul Griffiths at UK Tram said:

This exciting project forms part of our Low Impact Light Rail initiative which was launched to encourage new ideas within the industry that help to reduce costs in track and energy usage on the UK’s tram networks. Through projects like this we aim to improve the cost effectiveness of light rail, thereby assisting in bringing the service to more of our towns and cities.

Stage one of the Composite Overhead Line Structures project is expected to be completed by the end of January 2015 with stage two focussed on a demonstration of the pilot structure later this year.