A Study on the Flood Affected Flexible Pavements in Australia

Abstract

Roads were one of the most valuable assets damaged during the devastating flood of January, 2011 in South-East Queensland. Research by ARRB Group and Griffith University, with Austroads funding, was initiated in early 2013 to evaluate the impacts of extreme weather events such as flooding and frequent heavy rainfall on pavement deterioration. The research examines the structural and functional performance of flood affected flexible pavements using the Falling Weight Deflectometer (FWD) and surface condition data sourced from Brisbane City Council and Roads and Maritime Services of New South Wales, Australia. This paper presents the findings on the structural and functional performance of flood affected flexible pavements in Australia. A comparison is presented of before and after flood data on flooded and non-flooded sections of the pavements. The results indicate that the flood affected pavements suffer losing their structural strength faster than their normal deterioration rate. A reduction in the subgrade CBR value up to 67% and structural number up to 50% has been observed. The reductions in the subgrade CBR and structural number would not be so high and rapid if the roads were to deteriorate under normal weather conditions without the flooding event. However, re-testing a number of the pavement sections, several months or years after the flooding, shows a consistent trend of gaining the strength mainly due to the post-flooding rehabilitation works. Preliminary analyses conducted on the surface condition of flood affected pavements indicate a marginal loss of roughness, rutting and cracking. This research will improve the road network condition prediction for flooding events and is expected to identify the adaptation options to reduce the flooding impacts in terms of cost at road network level.