Cities should be able to adapt to changes, without disruption or deteriorating services. This requires infrastructures to be resilient enough to cope with rapidly-growing populations and unexpected events. However, many city dwellers live in inadequate conditions, with inappropriate infrastructure. There is therefore an urgent need for more sustainable urban environments – particularly to reduce risks imposed by climate change.
It is estimated that, by the middle of this century, the world’s urban population will have reached about the same size as the total global population in 2004 – with the vast majority of this urbanisation taking place in developing countries.
As a result, many cities are struggling to accommodate rapidly-growing numbers of people, to implement responsive urban planning and management procedures, or to meet citizens’ basic needs – such as housing, recreation, healthcare, transport, and education.
Slums, which currently house around one billion people (or one in eight people of the global population), are a key symptom of ineffective infrastructure planning. A slum is defined by UN-Habitat as an area whose inhabitants lack access to water and sanitation facilities, sufficient living area, durable housing and security of tenure. Such communities also tend to lack formal transport and energy infrastructures. Slums are usually disconnected from the grid, for instance – forcing people to obtain electricity through illegal connections (also known as electricity theft). Informal electricity supply negatively affects the community (through power cuts or price rises), while putting the lives of many at risk due to distribution boxes exploding, or accidents caused by poor wiring.
Millions of people die each year due to health problems associated with indoor air pollution – yet, in India, hundreds of millions of people living in energy poverty rely on unclean sources of energy for lighting and cooking. This could be tackled by making efficient and clean cooking, heating, and lighting devices more affordable for those who need them most. For example, low-cost solar LED lamps replacing kerosene lamps in Indian slums, and so reducing environmentally harmful carbon emissions.
Many city-dwellers are unable to access affordable and reliable public transport, as millions struggle daily with long, unsafe, or expensive commutes to work and school due to inefficient transport systems – with lengthy commutes common in both emerging economies and higher-income countries. In terms of urban planning, a city’s transport infrastructure can be improved by a combination of measures – including creating cities that are dense and human-scale (i.e. catering to the needs, habits and movements of the average person), optimising public transit systems and road networks, controlling vehicle use, encouraging walking and cycling, and promoting cleaner vehicles.
Vehicles are a major contributor to the decline of outdoor air quality and related health risks, while private cars are inefficient compared to mass transit solutions. A sustainable urban mobility model therefore aims to use buses, trams or trains rather than cars. In places where rail-based modes of transportation are not possible, Bus Rapid Transit (BRT) systems have been used as an effective substitute. BRTs provide a wide range of benefits: they are cost-effective and increase urban mobility, while considerably reducing congestion by decreasing the number of individual vehicles on the road.
Incorporating ICT solutions into existing transport infrastructures could also promote security, as bus stops and stations can be major crime hubs, with women disproportionately affected. Online bus tracking, live timetables, service updates, and ticket purchase services can be easily accessed from a computer or smartphone, helping people plan their journeys in advance –saving them time and money while reducing potential exposure to violence.
Sustainability through technology
A broad range of technologies can be used to support and improve energy and transport infrastructures in cities, from simple solutions to more complex systems. Challenges around energy access and the environmental impact of energy consumption, in particular, can be tackled by making clean, efficient technologies more affordable.
LED lamps are resource-intensive in their production, but their low energy intake (being 90% more efficient than incandescent lights and 50% more efficient than fluorescent lights) and long lifespan (35,000 hours, compared to 2,000 hours for incandescent and 7,000 hours for fluorescent) makes them truly sustainable for both private and public lighting. LEDs are made of 18 different minerals and metals, including indium, manganese, nickel, and selenium. They provide environmental, social and economic benefits for domestic users: for example, low-cost solar LED lamps used in Indian slums enable children to study at night, and women to work from home – increasing their household income while reducing fuel cost. Their use in public spaces is also beneficial, providing better quality lighting (hence boosting street security) while reducing costs – particularly when used in combination with solar panels (made from copper, silicon, molybdenum, beryllium, germanium, gallium, and indium).
Public transport, such as buses, increases urban sustainability by reducing the number of individual cars. Carbon emissions – and traffic noise – can be further reduced by using hybrid or electric buses, instead of conventional combustion-engine models. In places such as Colombia, Brazil, and several European countries, the use of hybrid buses has been increasing in the last few years, reducing the overall environmental impact of the transport system. The body, engine, and wheels of buses are usually made of iron, steel, and aluminium. Aluminium is widely used in the chassis (wheels, brackets, brake components, suspension, steering components and instrument panels) and automotive powertrain (pistons, cylinder heads, intake manifolds and transmission). It is also used for exterior attachments such as crossbeams, doors or bonnets. Magnesium is used in several components, but due to its low mechanical strength it must be alloyed with other elements, the most common alloy being Mg-Al-Zn. In the case of hybrids and electric buses, power storage batteries are made of lithium, cobalt, manganese, and nickel.
Catalytic converters were invented in France in the 19th century, but only became mainstream in the late 20th century due to the introduction of strict exhaust emission control regulations. Reducing the toxicity levels of gases and pollutants, they serve as a useful technology during a broader transition to electric vehicles. There are two types of catalytic converter: two-way or tree-way. Three-way ‘cats’ are the most effective, with up to 80% reduction of emissions when compared to regular engines. They can also be used in any internal combustion engine fuelled by gasoline, diesel or kerosene. Multiple metals are used in the making of catalytic converters, including platinum, palladium, rhodium, cerium, iron, manganese, and nickel, which are used in different types of catalysts.