The Road design handbook comprises four parts. `Basic criteria' addresses subjects that apply in general to the other three parts, each of which explores the design of one of the three road categories distinguished by the Sustainable safety of traffic concept, i.e. distributor roads, district access roads and estate access roads. For district access roads, the Sustainable safety of traffic concept requires that road sections have a relatively quick flow of traffic, while intersections emphasise changes in the direction of traffic flow. As such, intersections require low-speed traffic flows. There are two designs of district access roads, including the preferred 2x1 design and the 2x2 design, which can be implemented for capacity considerations. Furthermore, the following applies top both designs: they are closed to slow-moving traffic, the border line is broken and a carriageway separation is implemented.