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Road map aims to cut environmental impact

23 Jul 2018
Photo of heavy traffic moving at speed on the M6 motorway in England. (Courtesy: iStock/BrianAJackson)
Heavy traffic moving at speed on the M6 motorway in England. (Courtesy: iStock/BrianAJackson)

A highly detailed map reveals global patterns of current and potential future road infrastructure. The Global Roads Inventory Project (GRIP) integrated many previous datasets with the hope of informing global policies to reduce the environmental impacts of road development.

“Roads are important for socio-economic development by providing access to resources, jobs, and markets, but they also bring about various environmental impacts,” says Johan Meijer of the PBL Netherlands Environmental Assessment Agency. “Ecosystems are affected mainly because roads provide access to otherwise undisturbed areas. This results in habitat fragmentation, deforestation, and reduced wildlife abundance though disturbance, road kills and overhunting.”

Along with these issues, road construction also increases emissions of greenhouse gases and air pollution, driving global climate change and posing significant health risks.

Many previous efforts have mapped global road networks using georeferenced data, from groups including governments, commercial and non-profit organizations and through crowdsourcing. Typically, these maps are outdated, and are biased in coverage towards more developed nations, particularly in Europe and North America.

Meijer’s team aimed to solve these issues by unifying information from almost 60 previous datasets. The georeferenced data covered 222 countries and 21 million km of roads – over twice the total length of any current dataset. By showing the position of every road they had data for – from local tracks to major highways – the researchers created a global roadmap with an unprecedented level of detail.

GRIP global road density map on 5 arcminute resolution (approximately 8 × 8 km at the equator), representing the densities summed across the five road types. (Courtesy: Johan R Meijer et al 2018 Environ. Res. Lett. 13 064006)

The team also created a regression model that incorporated variables including each country’s area, population density, and GDP. The researchers concluded that high densities of roads are most likely to be found in wealthy, densely populated countries.

“To derive potential future infrastructure developments, we applied our regression model to future population densities and GDP estimates,” Meijer explains. “We obtained a tentative estimate of 3 to 4.7 million km additional road length for the year 2050, a 20% increase compared to the current situation.”

The team concluded that many roads are likely to be built within globally important ecosystems. “Large increases in road length were projected for developing nations in some of the world’s last remaining wilderness areas, such as the Amazon, the Congo basin and New Guinea,” continues Meijer. “This highlights the need for accurate spatial road datasets to underpin strategic spatial planning in order to reduce the impacts of roads in remaining pristine ecosystems.”

The team’s focus is on supporting and improving global policy assessments and outlooks, according to Meijer. “In order to adequately quantify the benefits as well as the impacts of roads, using global assessment models, accurate and up-to-date georeferenced information…is essential.”

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