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Electrifying the Limmittalbahn

On 28 August, the ground-breaking ceremony took place for the new Limmattalbahn tram route linking the growing urban conurbations in the Limmattal Valley, stretching north-west of Zurich.

Most of the population and commercial growth the nation’s largest city has been in the Limmattal area and this growth has put pressure on existing infrastructure, which created a need for a truly multimodal transport solution to link existing transport and facilitate further growth.

The new tramline links with existing S-Bahn metro services with buses, local and long-distance trains as well as airports. Additionally, there has been an emphasis on active transport – such as walking and cycling – incorporated into the design.

The project was originally conceived in 2010 with planning commencing in 2012. Formal approval was given in 2014, which allowed the tender process and design to commence. As the Limmittalbahn passes through urban areas served by different regional governments, the planning and design were unusually complex and a key consideration has been to minimise impact to the environment through noise, vibration and visual aesthetics. The electrification system is therefore a critical element of the new line.

The designers and planners proposed a sleek, contemporary network to the project team to fulfil the forward-looking aspirations of the region. This design ethos applied to the stations and bridges, as well as the electrification system, to create a comprehensive modern look.

Furrer+Frey was chosen to design and build the electrification system for several reasons, with the main advantage being over 90 years of international experience in providing electrification development for tramways and light rail systems. Furrer+Frey have a significant depth of experience in city centres and areas of aesthetic significance, a key
pre-requisite for this project.

On the Limmattalbahn, Furrer+Frey has worked closely with the project architects, planners, local government and stakeholders to ensure the electrification system was seen by all as a success. Through collaboration, early engagement and a significant effort to streamline communication, the best solutions were developed and any residents’ concerns were addressed before detailed design and construction began.

LIMMATALBAHN FACTS Total length: 13.4km (8.3 miles) Stops: 27 Power: 750V dc (urban), 1200V suburban Max. speed: 48km/h (30mph) in mixed-traffic; 60km/h (37mph) on segregated routes 92% segregated alignment

Urban and suburban designs

There has been a split between the requirements of more densely built-up inner city areas and those of suburban areas. In the former, most of the electrification system has been supported from adjacent buildings on span wires, reducing the need for new structures that could clog already busy streetscapes. The focus in these urban areas was to create equipment that is small, simple and as light as possible, minimising or removing the overhead clutter. This explains why a lower voltage was utilised in the inner-city area.

Significant collaboration with station architects allowed the OLE systems to be integrated with stations, minimising intrusion and continuing the sleek, modern aesthetic.

In suburban areas, without existing supports for the overhead line equipment, by working closely with architects and designers, a new structural mast was developed. A sleek tapered mast using a hollow box frame construction was installed. The side facing the track has a recessed section with attachments for electrification equipment; this allows for attachment on the inside of the mast and out of view. From the perspective of the general public there are no bolts visible, just clean tapered lines.

Recessed foundations and lighting are incorporated into the design; this removes the need for separate masts for electrification equipment and street lights. Rows of trees, in-line with the OLE masts, create a visual segregation and further minimise impact.

Furrer+Frey created a full-size mock-up in early 2017 that allowed planners, architects, local government and residents to see and feel them for themselves, prior to production. With the ground-breaking happening in August 2017, continued engagement proved critical in meeting project deadlines.

With construction now underway, and set to continue into 2019, Furrer+Frey will continue these successful communication and collaborative working methods to allow the benefits of the design to be carried forward into construction.




Feature originally published in October 2017 TAUT (958).