Rigid pavements of cement concrete or bituminous concrete have been generally so expensive that these materials have not been used outside cities; rather than put a strong surface pavement on a relatively poor subgrade, New Zealand engineers have tended to build a very strong subgrade and cover the surface with a light treatment just sufficient to meet the needs of traffic. They have developed the bituminous seal with the large chip. This method produces tyre noise, but it does give at a low cost a strong nonskid membrane protecting the subgrade.
Where the traffic is heavy, or in districts where the supply of chips is not readily available, other types of pavement have been developed. For instance, on the Desert Road, which runs north of Waiouru across the North Island Central Plateau, local material was used to make a bituminous mix which has given very satisfactory smooth riding for many years. On the motorways around Auckland, where the traffic is extremely heavy and tyre pressures are high, an even stronger bituminous pavement has been laid down. On the more congested urban streets and highways the tendency is to put down the high-type concrete or bituminous surface. In cities the most permanent surface used is a bituminous mix on a concrete base. With modern equipment available it is possible to construct either type to a high degree of accuracy and with smooth-riding and long-lasting surfaces. To cope with the weight and thrust of heavy transport buses it has been necessary to provide concrete loading areas at bus stops.