Climate changes in Norway: Factors affecting pavement performance

Abstract

The R&D program “Climate and Transportation” in the Norwegian Public Roads Administrations (NPRA) has assessed the consequences of a changed climate for pavement performance of the Norwegian road network. This has been done through a literature study and calculations of pavement performance with ME‐PDG for the present (2002‐2008) and future climatic situation (2070‐2100). The climatic changes in Norway implies an increase in temperature of 2.4 ‐ 2.8 oC and an increase in precipitation of 15‐25 %. Both the literature study and the calculations showed that higher maximum temperatures will lead to increased deformations of the bound layers. For unbound layer the deformations were expected to increase due to increased water content in materials with high fines content. On the other hand, decrease in frost index could lead to reduced bearing capacity problems in the spring thaw weakening period. Predicting the pavement performance in a changed climate is difficult due to the complexity of the road structure. To better understand how the single factors contributes to the pavement performance some special calculation analysis where made. The assessed factors were among others importance of increase in precipitation and temperature, variations between climatic zones, variation in sub‐ground and road structure materials and importance of traffic volume on rut development. One of the main findings was that the effect of increased temperature and thereby less frost index showed to be far more important than the effect of increased precipitation. In the end the calculations showed an expected increase in pavement life time of 13‐16 %. There is still some uncertainty linked to the calibration and the use of the Thorntwaite Moisture Index for Norwegian climate.