Sub-surface water may, by erosion or freezing and melting, cause cracks and breaks in roadways. Pits and grooves in road surfaces are the first signs of highway degradation. These may form as holes deep enough to trap a tyre and cause an axle to break. If left unrepaired, small fissures can allow water to erode the foundation of a road, and before long the entire road will require reconstruction. Roads in developing countries, and in heavily trafficked major urban areas in developed countries, tend to be subject to insufficient road maintenance which permit rutted and pitted surfaces and dangerously deep pot-holes to develop. A road surface can last thirty years with proper maintenance.
When road authorities are not able to afford maintenance work, the costs passed on to road users are larger than the "savings" in public expenditure. Over the life of a road, the total operating costs of vehicles are typically four to ten times the costs of road construction and maintenance. Since operating costs may easily double on poorly maintained roads, the economic loss is considerable.
Developing countries need to spend as much as $45 billion to rebuild roads fallen into disrepair through lack of maintenance. Over the past ten years, roads in many developing countries have been allowed to deteriorate beyond the point where normal maintenance could be effective. Traffic loading has been much heavier than intended, and maintenance has been widely neglected. Funds budgeted for highways have been mostly absorbed in expanding rather than in maintaining the network. Extra costs due to inadequate road maintenance chiefly involve spending foreign exchange on spare parts, fuel and vehicle replacement.