One of the primary considerations with any site is access and transportation. They are key factors in the success of any development; communities that aren’t readily accessible both inside and outside their boundaries simply aren’t sustainable. Access means safe, secure and healthy movement for all, whether old and young, rich or poor, and the viability of services, such as public transportation.
One of the problems with sustainable development on a site is that it requires around 40 houses per hectare to support public transportation and facilities like shops and schools. However, the average density on brownfield sites is currently 28 houses per hectare (it’s 22 on greenfield sites). That means the real need is for greater-density, mixed use sites, where houses, shops and business can co-exist, and there remains room for urban greenspace, in order for a community to be properly sustainable. In the Gorbals area of Glasgow, for instance, a 1990 development with 64 houses per hectare used mainly three storey terrace houses and four storey flats, some with shops on the ground floor and offices above. The streets were well-defined, and park space, and roads separated from pavements by a barrier of trees. The development had buses connecting with underground and suburban rail services. It’s proved so successful hat there have been attempts to reproduce it in Manchester, Leeds and London.
Studies have shown people are willing to walk 300-400 metres for a bus and 600-800m for light rail. So ensuring developments have good connectivity to public transportation and access to facilities are a vital part of sustainability. In that way public transportation usage will increase, and lessen the use of cars within the community, encouraging walking and bicycling. Cars have their place in this, of course, but their penetration and physical presence needs to be limited. Given that 29% of CO2 emissions in the U.K. come from transportation, and mostly from private cars, the need for integrated access becomes more vital. With rail as the main connection between cities, there would need to be a railway station every 6-km for the public to make good use of rail transportation, and stations can be the hub of a community.
That’s been the case in the vision for Ebbsfleet, in Kent, which has been based around the station. As proposed, the business core will consist of 4.5 million sq ft, eventually creating around 20,000 new jobs over the coming 20 years – a true mixed-use development. The plan is for over 3,000 residential units and 2,190 acres of new parks and open spaces. The transport system has been designed on the expectation that, with the integration of development and transportation, 40% of all journey over one kilometre will be made by non-car modes – double the current figure, and forming a model for future sustainable communities.
Facilities are also vital to making a community sustainable – schools, medical centres, shops and leisure centres. Facilities have catchment areas, the amount of people necessary to sustain, say, a school or a business. A good sustainable development with proper density would have shops within 800 metres, parks within a kilometre and leisure centre and a secondary school within two kilometres.
Facilities also need to be connected. Placing shops near a medical centre and a primary school, for instance, with a bus stop within 200 metres, means they enjoy the benefits of close physical association, and people can complete several tasks in one stop. If they’re within 800m of homes, walking will be a more viable option, too. Likewise, if a school shares a hall or playing fields with the community, that’s another form of connectivity and community. In this way the idea of thinking local becomes natural for residents.
The street is the main thoroughfare in a community. At present it’s used mainly by cars, but in a sustainable development you want to encourage much more movement by public transportation, foot and bicycle. That means much wider pavements, a separate marked cycle path and traffic restrictions. Ideas along these lines were part of the proposals for the community of Clyst Hayes near Exeter, as a “walkable neighbourhood principle” with ready access to the existing railway station. By making an area more friendly to pedestrians, you actively encourage walking.