Choosing the right pavement for the traffic
On medium to high-traffic highways, the best base course layer is good-quality crushed local stone (aggregate). Where this isn't available, we use lime or cement to improve the strength of the crushed stone. And for even heavier traffic, such as on motorways, we use an asphaltic concrete (bitumen) mix instead of stone.
Although concrete roads were built in New Zealand between WWI and WWII, they are currently not being used because:
- they are diffucult to maintain where services such as water, gas and sewer are located underneath
- they do not handle the long-term earth movements to which New Zealand is susceptible very well
- they are more expensive than asphaltic concrete
- they tend to be more noisy than asphaltic concrete without a noise-absorbing surfacing.
The volume of traffic on our highways means the pavements do deteriorate with time and sometimes need re-strengthening. How often depends on the road, but they typically last for between 20 and 50 years. We usually recycle the existing base course layer with additional new material.
CAPTIF
Research undertaken by the Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF) has significantly improved our pavement maintenance over recent years.
Find out how we monitor pavement condition.
