Prime Minister David Cameron and Mayor of London Boris Johnson have just celebrated the completion of construction work to build the Crossrail tunnel network. Crossrail is due to serve all 40 stations by 2019, connecting Reading and Heathrow in the west with Shenfield and Abbey Wood in the east.

Tunnelling in the central London section, from Paddington to Whitechapel and onto Stratford, involves stations along part of the Central Line, sections of which are known to contain amounts of potentially hazardous asbestos.

Asbestos was present everywhere

Three years after construction began on the central section in May 2009, it was also reported that asbestos was present everywhere across the entire London Underground network. Specific problem spots were said to be located at the eastern end of the Central line, running along the tunnel walls from Mile End station.

Nevertheless, it’s unlikely that there would be significant asbestos awareness of a potential health risk among many of the 1.26 billion commuters who use the Underground network every year.

Simply covered over the asbestos

Previously, it had been claimed that because of the “time, expense and disruption” involved in a safe and proper removal procedure, London Underground had simply covered over the asbestos with encapsulating paint, which could easily chip off and expose the deadly fibres. The location of asbestos-containing materials was often noted but removed “only when necessary”.

More recently, Transport for London (TfL) have emphatically stated that passengers and staff “are not at risk from exposure to asbestos fibres when travelling on the Underground”, and say they have also established “robust” controls, as required by the Control of Asbestos Regulations 2006.

“Asbestos train”

The Central Line was opened in the summer of 1900, reaching as far as Stratford and extending to Epping and Ongar from 1949 to the mid 1950s. Throughout this period asbestos brake pads were widely installed on the wheels of the underground trains and keeping the tunnels clear of asbestos dust was a part of the overnight ritual for London Underground.

Up until the UK banned asbestos in the 1980s, a vehicle resembling a vacuum-operated snowplough – known as the ‘asbestos train’ by the night crews – would be sent in the early hours of the morning to clean the asbestos dust from the tunnel walls. Following the ban, London Underground began to install a new type of non-asbestos brake pad on its trains.

Tunnel Cleaning Train delay

It seems the ‘asbestos train’ may ride again. In 2014, TfL revealed plans to remove asbestos containing materials from the underground network by the introduction of a train specially designed to remove dust. The ‘Tunnel Cleaning Train’ includes a carriage with large vacuum nozzles, which clean the surface of the walls as the train passes through the tunnel.

The train was to have been introduced in late 2013 but is now said to be delayed until 2017 or later because of the removal of asbestos-containing materials from the Underground rail network. According to TfL, the asbestos dust could be disturbed by the tube cleaning train, and potentially release harmful asbestos fibres into the atmosphere. TfL say that “certain classes” of asbestos-containing material (ACM) must be removed first otherwise the tube cleaning train would be “inoperable – or no longer viable – across 98 per cent of the London Underground network.”

Even then, not all of the network would be covered by the tube cleaning train.

Asbestos and contaminated ballast

TfL believe that even when the asbestos has been removed or “encapsulated”, the train would only be able to clean two thirds of the network. Cleaning of the remaining one third of the network would be prohibited where there is “asbestos, noise shelf and contaminated ballast”, which is mostly found on the Central, Jubilee and Northern Lines.

Research conducted in 2003 on the likely health effects of Underground tunnel dust concluded that levels were ‘highly unlikely’ to cause serious damage to human health and were below limits set by the Health and Safety Executive (HSE). A decade on, there have been calls by air quality controllers for more up to date analysis.