Access to food, water, education, health services and employment opportunities are all related to people's well-being and their ability to contribute to society. New research, published in Nature, by a collaboration between the University of Oxford, the European Commission’s Joint Research Centre, Google, Vizzuality, the University of Washington, the University of Queensland, Imperial College and the University of Twente has generated a detailed and up to date global map of accessibility to highlight development gaps between urban and rural populations.
The research, which used travel time as a measure of access, highlights the disparities in accessibility relative to wealth. Some 50.9% of people living in low-income areas (concentrated in sub-Saharan Africa) reside within an hour of a city compared to 90.7% of people in high-income areas.
The time we spend to travel to obtain resources, to use services or to get to and from our work has a cost, especially if it is time that could be better spent in other ways. Many people, especially in rural areas, have insufficient access to these resources and they may spend many hours travelling to cities to try and meet their most basic needs. Reducing inequalities in the accessibility of the services, resources, and economic opportunities offered by cities is a vital pathway to sustainable development and improved livelihoods for all people.
The team used new Google Earth Engine functionality and recent global datasets on transport networks, terrain, urban areas, land cover and international borders to estimate the time required to travel by land or water from any point on the earth’s surface to the nearest city (defined here as any urban area with more than 50,000 people in the year 2015).
The map is a substantial improvement on an earlier one, made by Andy Nelson in 2008, due to: the unprecedented availability of spatial data to characterise the different factors that affect travel time; the computational power of the Google cloud-computing system, and; the ability to use Google APIs and crowd sourced data to validate the model and travel time assumptions on a global scale.
The underlying model and the new map have been made available within Google Earth Engine to support further use of accessibility information in research and policy.
The 2015 map serves as important baseline information to support the equity agenda of ‘leaving no one behind’ which underpins the United Nations 2030 Agenda for Sustainable Development.
Estimating how accessible or inaccessible a location can be a useful predictive metric for research and policy related to food security, trade and conservation. The level of access to markets affects the choices of both food producers and consumers, while the level of access to forests, wetlands and other natural landscapes is associated with their conservation and protection. Detailed, spatial information on accessibility can support investment decisions that lead to better equality in access, more sustainable management of natural resources and improved long term resilience of both urban and rural communities.
- D.J. Weiss, A. Nelson, H.S. Gibson, W. Temperley, S. Peedell, A. Lieber, M. Hancher, E. Poyart, S. Belchior, N. Fullman, B. Mappin, U. Dalrymple, J. Rozier, T.C.D. Lucas, R.E. Howes, L.S. Tusting, S.Y. Kang, E. Cameron, D. Bisanzio, K.E. Battle, S. Bhatt, and P.W. Gething. A global map of travel time to cities to assess inequalities in accessibility in 2015. (2018). Nature. doi:10.1038/nature25181
- Online viewer for the accessibility map: http://roadlessforest.eu/map.html
- Map download page: https://map.ox.ac.uk/research-project/accessibility_to_cities
- Google Earth Engine: https://earthengine.google.com