Space for Cities

 

Sustainable cities include social, economic and environmental considerations in designing and managing the urban infrastructure, its roads and transport networks, buildings, green areas, and public services. Integrated development strategies take into account diverse territorial needs within and outside the city, including its peripheral areas and surroundings. Satellites can support city administrations to better manage urban assets and services, and also to better understand the interconnections among the different assets and services of the city and between the city and its hinterland. 

Growing urbanisation makes it necessary for city managers to have a precise overview of soil status and of land uses. A smart sustainable city is indeed one in which residential areas, green spaces and services are equally distributed, and a good proportion exists between the green volume and the built “grey” volume, which is a necessary condition not only to protect cities’ ecosystems and biodiversity, but also to grant a healthy life to their inhabitants.

As compared to other surveying techniques, satellite imagery offers a unique overview of land uses which is objective and comparable over time: satellite-based maps are already used in several cities worldwide to map land features and uses, create and update cadastral maps, plan and monitor the access to services and green areas, monitor soil status and subsidence and even to evaluate property taxes, among many other uses. Satellite imagery and navigation are used to create urban 3D maps, allowing public managers to visualise and virtually test different scenarios for the future development of the city.

Satellite imagery is, or it will be, an integral part of cities’ Geographical Information Systems (GIS). Where different GIS exist for different uses, they can potentially be combined by integrating layers of satellite imagery for the use of different municipal services.

Efficient and reliable transport systems are of paramount importance for cities. They are fundamental for cities' liveability and also for their economic competitiveness, fostering both business and tourism. The sector includes both private and public forms of transport (including trains, buses, trams, ferries, tube lines, cars, cycling and walking) and the possibility to shift among them. Indeed, being able to move around easily and having access to reliable information on itineraries, timings and traffic status facilitate the everyday life of cities’ inhabitants. Optimising transport and mobility while encouraging “ecofriendly” ways of transport also helps decrease pollution rates, with positive effects on residents' physical and mental health. Indeed, urban mobility accounts for 40% of all CO2 emissions of road transport and up to 70% of other pollutants from transport [1].

The European Commission has been fostering sustainable urban mobility since 20 years. In 2013, the EC launched the Urban Mobility Package, reinforcing its supporting measures in the area. Other initiatives on the same theme include CIVITAS, which has tested and implemented over 800 measures and urban transport solutions as part of demonstration projects in more than 80 Living Lab cities Europe-wide. Eltis is instead the main Europe's observatory on urban mobility, providing information, good practices, tools and communication channels to develop models of sustainable urban mobility.

Satellites can facilitate transport in cities in several ways and many of their applications, notably those based on satellite navigation, have already proven their efficacy. Indeed, satellite navigation is used to monitor the position of public buses, trams and shared car and bike systems in many European cities, providing information on timings and itineraries in real time. Satnav is also used to optimise traffic lights and to monitor traffic fluxes, collecting data that traffic managers will use to improve and regulate the circulation. It is also employed to monitor the transport of dangerous goods, minimising the risks of their transit within cities.

Satellite navigation, in combination with Earth observation, is used to monitor the effects of traffic on the street pavement. In the near future, Satnav will be an essential component of unmanned vehicles, as it is already the case in some pioneering cities. The versatility and wide availability of satellite navigation signals offer concrete opportunities to support urban transport and more innovative solutions are expected to emerge in the coming years.

The first concern of city administrations when dealing with built areas is the quality of the soil. To make sure that new and existing buildings and infrastructure are safe and sustainable, it is necessary to have a precise understanding of the hydrogeological features of the land and its changes. As an example, in cities built on soft soil (with a high concentration of water), soil subsidence could cause serious damages to people, street pavements and buildings. It is hence necessary to monitor soil status and movements and to be able to foresee them to intervene before the damage happens. City administrators also need to have a constant and complete overview of the transport, energy and water networks, to make sure that they function, that all residents have access to them, and that new developments are based on a holistic approach.

For what concerns buildings more specifically, the European Commission works extensively on subjects that affect construction and construction products. The issue is important, since the construction sector uses up to a half of all extracted materials and energy in Europe and generates about one third of all waste [2]. A review of recent trends and current practices demonstrates that there is an urgent need to embed sustainability in renovation and in new building and infrastructure projects [3]. This means rethinking the materials that are used for construction, preferring those that retain less heat, consume less energy, are less costly, more resilient to natural disasters and soil movements, and less polluting for the environment.

Satellites can help city managers making urban infrastructure and buildings more sustainable: satellite imagery allows for the precise mapping of buildings and infrastructure. It is also widely used to monitor soil subsidence and the risk of slopes with great accuracy, allowing city administrators to implement works where it is most urgent, with no need for costly field surveys.

Furthermore, satellite images, combined with ground sensors, allow for the identification and monitoring of urban heat islands, and for the identification of correlations between soil sealing, building materials and temperature. City planners can hence recommend construction materials according to the specific needs of the areas in which new buildings are created. Satellite imagery can be used to test different traffic and construction scenarios, and their impact on air quality, and to design new urban infrastructure accordingly. Satellite navigation is also useful in mapping buildings and infrastructure, and it is already employed to verify the accuracy of new buried optic fibre, gas and electric lines.

Here are some examples of how cities are relying on satellite applications to enhance their safety and resilience. More success stories are included in our Good Practice Database.

 

Prague (Czech Republic)

Monitoring urban sprawl using satellite information

 Bologna (Italy)

Satellite navigation to smoothen public bus traffic flows

Diemen (The Netherlands)

Infrastructure maintenance using satellite imagery

The Prague Institute of Planning and Development acquired historical aerial and satellite images of the city, suburbs and outskirts. This information provides a homogenous overview and classification of current land use and long-term developments in and around Prague. City planners use this to study changes in built-up areas, farm land and green spaces and to take decisions on prioritising smaller intervention areas, such as transport ‘hot spots’.

More than 1.000 buses use the Automatic Vehicle Location (AVL) system. The messages received by the central unit are automatically retransmitted to communicate the expected arrival times at the bus stops. Moreover, Bologna’s centralised streetlight system adapts to traffic flows in real time, relying on the information provided by the AVL system and by a network of around 1.000 sensors placed under the street pavement, which monitor the number of cars on the street. 

The city of Diemen ordered a city-wide deformation map based on satellite data. The Department of Infrastructure can determine how quick infrastructure is sinking in Diemen with millimetre accuracy. The deformation map allows practitioners to accurately identify damage and therefore correctly prioritise maintenance activities at every level (streets, neighbourhoods and districts). In addition, it shows the dynamics of the subsidence measured at each location, so the city can better prevent possible sewer emergencies.