Environmental impacts » Case study » Pollution

Keeping the dust down

Works to improve the track on the Northern line were carried out during 2006 at a pace never seen before on the London Underground. Thanks to a combination of careful planning and innovative working practices, the speed of work did not mean cutting corners on environmental issues. Quite the opposite, as illustrated by new measures to control dust in the tunnels.

“Clearly, when you are working in a confined space, dust is a potential problem, particularly when breaking and mixing concrete” says Paul Watson, Delivery Manager. “We have introduced a comprehensive dust management system to keep this under control, both creating as little dust as possible and minimising the chances of it becoming airborne.”

The new system uses nebulisers placed at each end of the work site to spray a fine mist of water. As the mist saturates the air, it reduces airborne dust as well as cooling the tunnels, making the working environment more pleasant.

Cement is kept in bags to reduce the amounts of dust released and pollution from mixing cement is kept to a minimum as well.

Once the work is finished, the tunnel is cleaned thoroughly using specialist industrial vacuum cleaners.

Weekend working was key to the success of this project, which in total represents a £40m investment in track upgrade. “Because our normal night-time engineering hours are so limited, the weekend possessions enabled us to complete work in one weekend that would otherwise have taken three months,” Paul explains. “We worked 40 weekends, starting in April, which was very demanding for all involved, but we renewed 10.4km of track on 46 different sites – and completed 60 per cent of all planned track work on the Northern line four years ahead of our 2010 deadline.”