Increasing the life of sprayed seals may be an important response to future major rises in the cost of bitumen and the need to reduce greenhouse gas emissions. A seal life model, based on road trial data, was used to prepare seal life maps for Australia, South Africa and New Zealand. These showed that Australia has the greatest range of calculated seal lives due to its extreme climatic conditions. South African seal lives tend to be clustered towards the short life end of the overall distribution, whereas New Zealand seal lives are towards the long life end. The model was used to estimate possible increases in seal life due to measures such as improved bitumen durability, the use of larger seal sizes and resealing based on need rather than age. These measures have disadvantages such as increased initial cost, greater road noise or increased risk of bleeding and, while unlikely to be adopted in the short term, may become necessary in future. (a).
Abstract