unpaved

Unpaved refers to surfaces of roads, paths, or runways that have not been surfaced with manufactured materials such as asphalt or concrete. Common unpaved surfaces include dirt, gravel, crushed stone, and packed earth. Unpaved routes are most common in rural areas, developing regions, and certain temporary or low-traffic facilities, where paving is not economically or technically feasible.

Unpaved roads are laid by shaping the subgrade, spreading an aggregate layer (such as gravel or crushed stone), and compacting it with rollers. Adequate drainage is essential, often achieved through crowned profiles and drainage ditches or cross-pans. Maintenance typically involves grading to restore the surface, adding material, and re-compacting after weathering, with occasional stabilization using binders or geotextiles.

Advantages include low initial construction costs, simpler repairs, and a surface that can tolerate certain heavy loads with proper maintenance. Disadvantages include dust, mud in wet weather, surface ruts, erosion, variable ride quality, and higher maintenance frequency. Safety considerations involve reduced traction on loose material, uneven surfaces, and seasonal hazards such as flooding or snow drifts, prompting speed reductions and warning signs.

Unpaved surfaces have a long history as the predominant road type before widespread paving. Today they remain common on rural highways, forest and mining access roads, and temporary routes. Environmental effects include sediment runoff and dust; well-maintained unpaved roads can promote infiltration and reduce heat islands, while poorly maintained ones can contribute to erosion and degraded waterways.