The Adverse Effects of Road Traffic Congestion on Soil

Soil Compaction

• The primary adverse effect of road traffic congestion on soil is the reduction of pore space in the soil. When soil particles are compressed together, the amount of gases and liquids that can be held in the soil is decreased. Air and water are vital to the life that soil sustains. Compacted soil cannot support plants, microorganisms and animals as well as it normally could. The damage done to the ecosystem from soil compaction has long-term effects on an area.

Pollution

• Old roads, in particular, contribute to polluted soil. With time and heavy traffic, heavy metals from leaded gasoline can build up in the soil around a road. Old roads are more likely to have been exposed to leaded gasoline and, in turn, have had more time for toxins to accumulate. Even though lead is no longer added to gasoline, the soil around roads can still become polluted due to combustion fumes.

Types of Roads

• Traffic congestion can occur on any type of road. Road surfaces can range from dirt and gravel, to asphalt and concrete, with heavy traffic most likely on the latter type of roads. These roads have the hardest surfaces in order to support increased traffic. During their initial construction, the soil had to be compacted to a certain degree to make the surface stable. The efforts that go into making these roads and the pressure that traffic congestion exerts on them make it very difficult for these roads to be reclaimed and used to grow anything on. Dirt and gravel roads are mostly in rural areas. If there is a fair, auction or other large event, these roads can be overwhelmed by traffic congestion. The heavy traffic can make repairs necessary and further compact the soil.

Erosion

• Compacted soils from heavy traffic on roads can lead to erosion. When soil is compacted, it cannot absorb water as easily. The water that normally would have been taken into the soil begins to run along its surface. This moving water picks up soil particles; and as it gains speed, it can strip away the surface of the soil. Soil erosion is very damaging since it takes soil thousands of years to be replaced naturally. High traffic roads are typically built with ditches on either side that must be constantly maintained to prevent soil erosion.