The principle that the delivery of safe and effective road services is a duty owed to the road users provides the impetus for a quality assurance (QA) program. QA refers to all of the criteria and activities used to verify and audit road performance. Road conditions are measured in terms of pavement distress extent and severity, structural capacity, and riding quality. The most dominant surface distresses are roughness, potholes, dust, and rutting (plastic deformation under the wheel path). Simplified QA criteria are presented related to surface distress severity, traffic loading, maintenance expenditures, vehicle operating cost (VOC), and economic indicators such as net present value and internal rate of return. Construction and maintenance work procedures and their QA and quality control (QC) procedures are introduced. The choice between using rougher surfaces with more severe potholes and dust distresses and higher VOC is compared with the use of smoother roads that require higher maintenance and rehabilitation costs but save the users money. Although the economic return of upgrading the dirt road to a silty sand surface is 12 percent, the road's owners may select to postpone the road improvement and spend less on rehabilitation and maintenance and allow a higher VOC. On any given road network the trade-off between spending on routine maintenance and saving in VOC should be carefully evaluated to provide a balance among user cost consideration, agency costs, and acceptable road performance.
Samenvatting