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Tube Lines’ very own live wires invent track safety device

Permanent current rail indicator device (P-CRID) developed by Tube Lines improves rail safety and increases efficiency

Every night Tube Lines has in the region of 5,000 workers busy improving the Tube and their protection is paramount. Now they have developed a permanent current rail indicator device (P-CRID) – a trackside fixture that lets engineers working on the Underground know when the live rail is turned off from a place of safety. The groundbreaking P-CRID invention designed by Tube Lines engineers represents the biggest step-change in the safety of track workers for decades.

Work to maintain and upgrade the Underground each night cannot start before all passenger trains are taken out of service and the track current switched off. Only then can certificated protection masters trained to use a handheld current rail indicator device (CRID) access the track to test that the 630 voltage traction current is actually off. Once confirmed, the army of workers begin their jobs of improving the Tube system.

This safe system of working has been in place on the London Underground network since the mid 1980s and is recognised by relevant health and safety experts. It is also a method used across the rail industry in the UK. Nonetheless, over the past ten years the rail industry has set about trying to find ways to further improve the established method for accessing and testing for traction current to enhance the protection of hundreds of protection masters and thousands of track workers each night. However, no new design has tested fail-safe. That is until now when Tube Lines’ own engineers designed the P-CRID.

Tube Lines has been encouraging its employees to challenge traditional methods of working to continuously drive through improvements in safety and performance. In response to this challenge, a team of Tube Lines engineers set about reviewing the process for ensuring safe access to the track, and whilst there have been no major injuries caused by checking the traction current status a safety and efficiency improvement opportunity was spotted. The team turned their attention to designing the P-CRID.

The P-CRID is permanently fixed to the track and gives a fail-safe and clear indication of traction current from a place of safety, eliminating the need for a protection master to access the track to check traction current status. The unit also constantly monitors its own condition and connections and in the event of a disconnection or internal fault it will fail-safe and warn workers not to go onto the track.

The team behind this groundbreaking device designed, built, assured, and commenced installation within just 12 months – a timeframe unheard of in the rail industry for such a major improvement. The Tube Lines patented P-CRID is now at full production stage and has been installed at over 300 track access locations. The device will be fully implemented on Tube Lines’ lines over the next two months.

Not only does this innovation provide improved safety conditions for Underground work teams, it also delivers faster track access and is simpler to maintain. For example, the original handheld device can easily be damaged and needs to be overhauled each year, whereas the new P-CRID requires minimal maintenance. The device has a design life of over 25 years and the battery only needs to be replaced every two years.

Gary Downie, delivery manager of lifts, escalators, structures and depots for Tube Lines who managed the P-CRID project said: “In this industry ensuring the safety of staff and passengers at all times is paramount. Our P-CRID innovation represents a massive step-change improvement to the way Tube engineers are protected when working on the track. This is one of the biggest safety improvements made in the industry for decades.

Diarmaid O’Tuathail, director of health, safety and environment at Tube Lines said:
“Safety is at the heart of everything we do so I’m delighted with this innovation which virtually eliminates the risks faced by people checking the electricity is off so that improvements to the Underground can take place safely. Hundreds of people across London will benefit every night.”

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