three reasons two wheels are great for cities

נשלח 25 בנוב׳ 2011, 14:04 על ידי Sustainability Org   [ עודכן 25 בנוב׳ 2011, 14:53 ]
16 November 2011, by Joe Peach

Bicycles are often praised for being energy efficient and non-polluting, but what exactly does this mean? And how about the environmental sustainability of bicycle networks? Here are three reasons why bicycles and bicycle networks are good for creating environmentally sustainable cities:

Embodied Energy

The amount of energy required to produce a bicycle is tiny compared to many other forms of transport. A 7.2kg road bicycle with a carbon frame uses 11,546,658,000 Joules of energy during its production compared to 118,284,466,000 for a ‘generic car’ produced in America in 2008 (Figures via WattzOn). Variations exist based on bicycle type and other external factors, but even taking this into consideration, the bicycle has a low embodied energy. Additionally, bicycle lane construction is less energy intensive than roads for automobiles, requiring a smaller amount of space and minimal foundations.

Air quality

A bicycle’s environmental sustainability is about more than just low embodied energy. If enough people switch from polluting transport modes to a bicycle – a zero emission form of transport when in use – there is potential for reduced carbon emissions and improved air quality in our cities.

Mexico City and London both have low levels of bicycle use, making up 1% and 2% of all trips respectively. Is it a coincidence that both cities also have notoriously bad air quality? Perhaps not, though it would be both foolish and a lie to attribute this entirely to modal split. However, every person who switches from driving a car to riding a bike is responsible for less carbon emissions. If we can make cycling a real alternative to other forms of transport, something which an improved bicycle network is an integral part of, then achieving such a modal shift would be more likely, and improved air quality could become a reality.

Noise pollution

Pollution is about more than just emissions. Noise levels in cities can also be considered a pollutant, with associated long term health risks:

Noise can increase the levels of stress hormones such as cortisol, adrenaline and noradrenalin in the body, even during sleep. The longer these hormones stay in circulation around the bloodstream, the more likely they are to cause life-threatening physiological problems. – Alok Jha

Some cities are even highlighting noise pollution in their sustainability agendas. Vancouver 2020 – ‘an action plan for becoming the world’s greenest city by 2020’ imagines a highly sustainable future for the Canadian city, envisioning ’less pollution and cleaner air, less machine noise and more birdsong’. Despite veering off into an almost fairytale-like tale of sustainability, noise pollution considerations show that the issue is on the sustainability agenda, at least in some cities. With the same report listing an increase in levels of cycling as integral in developing communities, the role of the bicycle in reducing noise pollution is further hinted at.

Sadly, bicycle networks and bicycles themselves aren’t some panacea for a city’s environmental challenges. The analysis of urban air quality is complex, affected by local factors such as weather, geography and industry – something bicycle networks have no control over. In fact, cities will always use energy, emit carbon, and make noise. However, a city that depends on bicycles more than other automated forms of transportation will require less energy, emit less carbon, and make less noise.