50440 Fear of ‘explosion’ due to high density of dust in tunnel

February 2012 in London Underground

Work environment South East

A reporter is concerned about the build up of dust in Central Line Underground tunnels.  The reporter believes that this poses a small risk of explosion. 

The reporter states that there appears to have been a gradual build up of dust, consisting mainly of easily flammable components, over the last few years.  They believe that the current method of cleaning tunnels is ineffective, particularly for tunnel roofs. Cleaners use industrial vacuums, which are strapped to their backs, to suck the dust from the tunnels.  

The reporter suggests the London Underground redeploy the tunnel cleaning train as it collects a higher percentage of loose dust particles that lie within the cables and walls. 

Could London Underground:

• Assess the level of dust in the tunnels?
• Consider improving the current cleaning methods used in tunnels?
• Consider redeploying the tunnel cleaning train?

Response from London Underground

The level of dust in the tube tunnels is monitored by visual inspections which take place at least once a month. In addition the measurement of airborne dust levels is done, as required, by specialist companies. These observations and measurements show that dust levels on the London Underground network remain steady and very low, at less than one third of the Health and Safety Executive exposure limit for dust, and therefore do not pose a significant risk for either staff or customers.

LUL takes all reasonable measures to reduce the build up of dust. For example, prior to essential works being carried out on stations and in tunnels, a number of precautions are put in place to minimise the creation of dust and to clean up any dust that is unavoidably generated.

LUL has also ensured that the new rolling stock being introduced, through the course of upgrading the Tube, generates a lower level of dust than existing trains.

The existing manual cleaning arrangements for removing dust from the tunnels has probably been improved as far as possible given the limited power available in the tunnels for portable vacuum cleaners and the difficulty of getting safe access to clean the higher sections of the of tunnel and cable runs.

The old tunnel cleaning train is obsolete and beyond economic repair. LUL has therefore commissioned a replacement tunnel cleaning train which will work more quickly and be more effective than the old train. This will progressively improve the efficiency and effectiveness of the cleaning regime, in due course. This new train is due to enter service in 2013.