This design catalog is intended to give general structural design and mix type selection guidance for some typical Washington State HMA pavements. It is organized by general purpose, with each use type being addressed on a different page. These guidelines are intended for use in lieu of other guidance or specification. They are not intended to supercede official guidelines or specifications.
This page puts forth some basic guidance for use when designing HMA pavements and is meant to be used as a checklist. When designing a pavement, the guidance listed here should at least be considered. The guidance contained on this page is not absolute, however design and construction in conflict with this guidance should (1) only be undertaken for a specific reason and (2) only carried out once the associated risks are understood.
Rural roads consist of local roads whose primary function is to provide access to adjacent properties and arterial routes. As described here, rural roads are low car and light truck traffic with some bus, heavy truck and local farm traffic. Speeds vary but in many locations they can approach highway speeds.
Arterials roads provide service to large areas and usually connect with other arterial roads or highways. They are generally characterized by high traffic volume, heavy loading and widely varying speeds. Highways are roads that provide primary transportation routes between geographic locations such as cities and towns. They are characterized by varying traffic volume, heavy loading and widely varying speeds.