• How the green wall at Edgware Road will look


    How the green wall at Edgware Road will look

Cleaning London's air
By editor | 18 Nov, 2011
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Green infrastructure projects can mitigate against pollution in our towns and cities, as this Transport for London initiative illustrates.

With the threat of hefty fines from the Europe, itâs vital that London keeps a close eye on its air quality. The capitalâs levels of a pollutant known as PM10  â largely caused by traffic emissions â are within the limits set by the European Commission, but tests have identified several hotspots where action needs to be taken to ensure it remains at safe levels.
Financed by the Department for Transport at the request of the Mayor, the London Clean Air Fund will be targeting the areas at risk to reduce the levels of PM10 by a third by 2015. One of the projects the £5m fund will be spent on is increasing the green infrastructure in the city, including planting 500 trees and shrubs near to some of the busiest roads.

Transport for Londonâs chief operating officer, Garrett Emmerson, says: âWe are beginning to implement a number of projects from the Clean Air Fund now and Londoners are likely to start noticing these. These are measures we can introduce to target local PM10 hotspots and put in place fairly quickly and build on our continuing work to improve air quality across London.â The roads that will receive the additional trees and shrubs are Park Lane, Upper Thames Street, Western Avenue (A40), Old Kent Road (A2), Brixton Road (A23) and the Woolwich Flyover (rear of Tunnel Ave).

Outside Edgware Road tube station, adjacent to Marylebone Road, a green wall is being installed to trap the pollutants. Studies across Europe and the USA have shown the potential of vegetation to trap PM10. TfL will be monitoring the success of the Edgware Road project, with the help of the Air Pollution Research in London (APRIL) group. The green wall involves around 180m2 of vegetation â a mixture of evergreen and perennial plants that are known to survive in a roadside environment. The plants will be grown in a peat-free substrate know as Grodan, which has achieved the European Ecolabel for sustainability and is chemically inert. The structure that supports the plants includes a waterproof backing called Ecosheet, which is manufactured in the UK from recycled material.

The plants that have been chosen have not been tested for their air pollution benefits before, so TfL is using a selection of robust plants suitable for a south-facing aspect in a highway environment. It has included plants with smaller leaves and a variety of textures and different growth habits to enhance their ability to trap small particles PM10

Green wall ingredients
Lavandula âMunstedâ = Lavender
Erysimum âBowles Mauveâ = Wallflower
Geranium âMax Freiâ = Geranium
Stachys âSilver Carpetâ = Lambâs Ears
Carex testacea = sedge
Heuchera âPlum Puddingâ
Veronica âWaterperry Blueâ = Speedwell
Vinca minor âLa Graveâ = Periwinkle
Waldsteinia ternata
Euphorbia âHumpty Dumptyâ = Spurge
Liriope spicata âBig Blueâ = Lilyturf
Acorus âOgonâ = Sweet Flag
Lonicera pileata. âMaigrunâ = box-leaved honeysuckle
Euonymus âEmerald nâ Goldâ } = shrubby Spindle
Euonymus âEmerald Gaietyâ  } = shrubby Spindle

In addition to the green infrastructure projects, the Clean Air Fund will pay for:
⢠   A team of five eco-marshals will be visiting taxi ranks in pollution hotspots across London to reduce engine idling time for taxis and minicabs whilst promoting eco-driving courses designed to reduce emissions, as well as save cabbies money through efficient driving techniques
⢠   A no-idling campaign to encourage drivers to switch off their engines when stationary
⢠   The expansion of a successful 'dust suppressants' trial
⢠   The installation of diesel particulate filters to buses on selected routes running through central London
⢠   A programme of engagement with businesses to promote sustainable travel and reduce their air quality impact.

This article appeared in the November/December 2011 issue of Greenbuild magazine. For a free subscription click here .

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