Modified MEWPs Go Underground


The Four Lines Modernisation (4LM) programme is a major Transport for London (TfL) project to upgrade the Circle, District, Hammersmith & City and Metropolitan lines. The aim is to boost capacity, with trains running faster and much closer together, improving journey times and train frequency.

The modernisation work includes installing a new communications-based train control (CBTC) system to allow new trains and the control centre to ‘talk’ to each other by radio.  This means installing approximately 450 radio antennae every 150m in the tunnels.


London Underground and Thales


London Underground (LU) and Thales turned to TRS to find an efficient, fast and cost-effective way to carry out the installations.

We proposed to use mobile elevated work platforms (MEWPs) as they have the ability to easily reach any required part of the tunnel profile. They also offer efficiency benefits, allowing teams to achieve more in the limited time available during possessions.


We chose the Promax RR14 EVO rail-mounted MEWP for the job.  Over the coming weeks we worked closely with the TfL team to modify the plant so it met the special constraints needed for operation in LU’s tunnels.

With TRS, TfL and our suppliers working together to formulate, design and make the practical modifications, the MEWPs were approved in less than 3 months.

Four significant alterations were made:

  1. Design and installation of a blind spot camera system
    When unrestricted by space MEWPs can swivel 180º, so the operator/driver faces the direction of travel. However, the machine cannot swivel fully in a tunnel and must be driven in reverse either to or from the work site.We therefore installed a camera on the far end of the machine from the driver and a monitor screen by the driver in the operating platform, so a clear path could be seen at all times.
  2. Enhanced fire suppression
    To operate in LU’s tunnels, all plant must have a fire suppression system. We fitted patented Firetrace detection tubing and extinguishant.
  3. Operator crush protection system
    A special anti-entrapment system was designed and installed by the MEWP manufacturer, Promax. This is an additional frame built over the platform’s operating controls with an automatic power cut-out. The frame prevents someone pushing against the levers if they get trapped between the platform and the tunnel and automatically cuts power to the controls.
  4. Use of EcoPar fuel
    We used EcoPar fuel, a natural gas, low carbon fuel, to power our MEWPs. EcoPar contains no sulphur, no aromatics and no benzene, dramatically reducing the production of harmful diesel particulates.  This made it especially beneficial for use in LU’s tunnels where air ventilation is poor.


Following the modifications, TfL issued its Certificate of Technical Performance for Rolling Stock, a Plant Approval Certificate and a Use of Plant Safety Plan for the Promax RR14 MEWPs to enable and authorise them to be used on the project.

A total of eight MEWPs were modified for use on the 4LM programme and are being used to install the 450 antennas, as well as the cable runs and other associated equipment.

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