Road expansion means the growing number of roads being built worldwide. More people and higher economic growth, especially in developing countries, are the main reasons for this increase. However, decisions made by transportation planners also influence how roads are expanded. Between 2010 and 2050, the total length of new roads planned is expected to be enough to go around the Earth over 600 times. About 90% of these new roads will be built in developing countries. Africa and Southeast Asia are expected to see a lot of road expansion in the near future.
In Asian countries, road expansion is an important part of building better infrastructure. This growth is driven by more people moving to cities, economic progress, and the need for better connections between places. Countries such as China, India, and Indonesia have plans to expand their road networks to handle more traffic and trade. These projects often face problems like acquiring land, dealing with environmental effects, and finding enough money to fund them. However, they are important for helping economies grow and improving access to services in remote areas.
Roads help people reach markets, health services, and schools. However, they can also harm the natural environment and affect communities and economies. Some people disagree about whether building more or wider roads actually reduces traffic jams.
Effects on the Environment
The growth of roads can greatly affect natural environments. Building and using roads can harm wildlife by causing many animals to die. Roads can either stop animals from moving freely or make it easier for them to move.
When roads are built, they can break up habitats, making it harder for animals to move, migrate, or find mates. This also changes the environment near roads, affecting how plants and animals grow. Road expansion can make it easier for people to reach natural areas, leading to more hunting, cutting down trees, and mining. These activities, along with fires and changing forests into other types of land, are major reasons for the loss of tropical forests worldwide.
Roads increase deforestation by giving people access to forests that were once hard to reach. This allows unofficial roads, legal and illegal logging, and the use of land in areas that were not disturbed before. It also helps people take over land for farming or other purposes. Studies show a strong link between building roads and losing forests in places like the United States, Europe, and China. In Europe, about 95% of all forest loss has happened within 5.5 kilometers of roads, showing that roads are a major cause of forest loss.
Roads also help hunters and poachers reach areas where animals live, increasing both legal and illegal hunting. In Central Africa, the biggest reasons for fewer elephants were being close to roads and having no law enforcement. Between 2002 and 2011, a sharp drop in African forest elephant numbers was linked to more roads being built. In equatorial West Africa, the loss of gorilla and chimpanzee populations was mainly because of hunting that increased as roads expanded, making poaching and habitat changes easier.
In areas where forest management is weak, road building can happen without rules, breaking up important natural areas and protected lands. In Africa, planned and completed road projects cross 345 protected areas, including 69 that are especially valuable, such as national parks, World Heritage Sites, and Ramsar sites.
Effects on the economy
Building better roads makes it cheaper to move goods, especially for people in remote areas. When more people can buy goods, farmers and other producers can sell more of their products, which helps their industries earn more money. In countries like Peru, Bangladesh, and parts of Sub-Saharan Africa, better roads have helped reduce poverty by increasing the amount of goods produced and sold. Improved roads also help people move from growing just enough food for themselves to growing specialized crops for sale. This can help communities earn more money, but it may also make them more dependent on outside markets and goods. This change can either improve food security, because communities no longer rely only on their own farming, or it can hurt nutrition if they stop growing a variety of crops.
Connecting remote areas to urban markets can also change how rural areas work. In the Democratic Republic of the Congo, soldiers control urban markets more than rural ones, so farmers and hunters must pay more money for protection and get less profit. More active markets can sometimes harm the environment. In the Democratic Republic of the Congo, more large and endangered animals are hunted for sale in urban markets than in rural ones.
Roads must be carefully planned and built to avoid harming the land and water. In hilly areas, roads are often built by cutting hills and filling valleys to make the ground flat. This process usually removes plants near the road, which increases erosion and sends more dirt into water sources. This can change how water moves, lower water quality, and make water warmer and cloudier. Poor drainage, culverts, and bridges can also block water flow, causing flooding during heavy rains.
In mountainous or steep areas, roads increase the risk of landslides, especially in wet regions. Activities like cutting hills, removing plants, and poor drainage contribute to more landslides near roads. In the Brazilian Amazon, about 90% of fires happen within 10 kilometers of roads.
Building roads in forests increases the number of fires. This happens because people may start fires on purpose to clear land, fires may spread from nearby areas, or fires may happen accidentally due to more people and vehicles. More fires mean more loss of plants and more carbon released into the air, which changes the types of plants and animals in the forest.
In developing countries, most money for new roads is spent on building them, not on keeping them in good condition. Many new roads are built in areas with heavy rain, and over time, they become damaged and unusable quickly. Damaged roads cost more to use because travel takes longer or vehicles break down. Cheap roads that are poorly built may cost less at first but are more expensive to fix and use over time.
Keeping roads in good condition requires long-term money and effort, but sometimes this money is stolen or misused. Building roads that are not strong enough and need more repairs is common in some countries, which wastes public and private money. These problems are more common in places where corruption is widespread.
More roads encourage people to buy cars and use roads more often. This causes more damage to roads, increasing repair costs. More cars and roads also lead to more accidents, especially in places where roads are poor or car use is new. More roads lead to more traffic, which causes even more road damage. Because of this, studies in developing countries often find that fixing existing roads is better than building new ones.
Effects on societies
In developing countries, important services like healthcare and education are often found mainly in cities, with few or none available in remote or rural areas. Expanding roads makes it easier for people in these areas to reach cities, which helps improve education. In Bangladesh and Madagascar, better roads in rural areas led to higher education levels. Also, easier access to cities allows remote communities to reach healthcare services, such as medical supplies and information, and has been linked to better health results.
Improved roads help create more job opportunities. In Indonesia, better roads led to more jobs in manufacturing and fewer people working in farming. However, more people looking for jobs can lower wages in an area, which can hurt people’s livelihoods.
While better access to city services has benefits, more people moving to already crowded cities can make it harder for cities to handle growing populations, especially in developing countries. This can cause problems like more crime, greater inequality, and health issues.
Expanding roads can force local people to move, and indigenous groups are often the most affected. This happens when non-indigenous people move into an area for jobs or to use local resources. These people might take over land through unfair methods like stealing land or illegal settlement. While this can lead to more development, it harms indigenous communities.
Roads can be especially harmful to remote communities. Large road projects bring temporary workers, which increases demand for services like illegal activities. Roads in remote areas also encourage harmful actions like illegal logging, mining, hunting, smuggling, and drug production. These activities can change the culture and social structure of local communities, with the worst effects on indigenous groups.
Indigenous communities that have lived in remote areas for generations see their traditions and ways of life changed by new roads. Roads can harm the beauty of natural landscapes and disrupt cultural practices. Non-indigenous people moving in can take land that belongs to indigenous groups, and increased hunting can change traditional practices. These changes damage the cultural heritage of indigenous communities and lead to the loss of their identity.
Workers building roads and new settlers can bring harmful pests and diseases to communities. This is especially dangerous for indigenous groups who are not used to or immune to these diseases. For example, building Route 8 in Bolivia in the 1970s caused 45% of one indigenous community to die in one year.
Roads can spread diseases like malaria and make communities more vulnerable to diseases they rarely face, such as HIV. Roads act as paths for pests and germs to move between areas. In Ecuador, villages near roads had 2–8 times more disease-causing germs than remote villages. People living near roads also had higher rates of dengue fever, malaria, and HIV compared to those in remote areas.
The movement of non-indigenous people through roads and the increased contact between groups can cause conflicts, such as between indigenous Amazonian tribes and loggers or miners. In war-torn areas, better road access can speed up conflicts and make them worse. In the Democratic Republic of Congo, areas with better road access experienced more violence, which reduced the well-being of people living there.
Reducing the impacts of road expansion
There are several ways to reduce the effects of road development on the environment.
A common idea is that expanding or improving roads in areas that are already settled causes less harm to the environment than building new roads in untouched forests. However, expanding roads can still harm the homes of endangered animals and damage rare ecosystems, such as lowland tropical forests. This is becoming more common as new roads are built to improve older, poorly developed road networks. These older roads often include rough paths and temporary routes. Studies in developing countries show that improving existing roads is usually more helpful than building new ones.
Examples of road expansion projects include Africa’s development corridors, which aim to support trade between countries; Indonesia’s development corridors, which focus on farming, mining, and logging; and China’s Belt and Road Initiative. In northern Sumatra, Indonesia, plans to extend the Trans-Sumatran Highway could harm six of the eight key conservation areas in the Leuser Ecosystem, which is home to 89% of the remaining habitat for Sumatran orangutans. Road development in this area has been predicted to play a major role in the decline of orangutan populations.
To protect the environment, road planning should avoid expanding roads in areas that are ecologically sensitive. Measures like limiting the width of roads and building wildlife crossings are being studied as ways to reduce harm. Limiting road expansion also helps communities and economies in developing regions. Many roads in remote areas do not provide clear benefits and carry high risks. A study of 33 planned development corridors in sub-Saharan Africa found that less than one-fifth of the projects were clearly justified. Most road improvements will focus on upgrading older roads rather than building new ones. For example, the Trans-Borneo Highway in Sabah, Malaysia, will mostly use existing logging roads or two-lane roads planned for 2033.
Better planning and assessment methods, such as cost-benefit analysis, land-use planning, and environmental impact studies, are important for improving road projects.