Significant cost savings, rapid construction, improved safety and reduced environmental damage are the key advantages of this innovative solution to road embankment failures. The solution involves the replacement of collapsed earth fill with ultra lightweight expanded polystyrene blocks placed behind lightweight retaining walls, which can be up to eight metres high. The solution is particularly suited for situations where the road formation has been constructed as a sideling cut and fill and has been lost, or partially lost due to a landslide. The technique was developed by VicRoads in 1995 to enable an earlier opening of a tourist road located in steep mountainous terrain, which had been closed by up to 53 landslips, just prior to the peak tourist season. Had they been repaired using conventional treatments, the road would have been closed for up to six months, and would have meant long and inconvenient diversions. Using the lightweight expanded polystyrene block treatment, the worst of the slips were repaired within two weeks, allowing the road to be opened in time for the Christmas traffic. In addition to an early re-opening of the road, it was estimated that the 26 landslide repairs carried out on this road using expanded polystyrene saved approximately $2M over conventional repair treatments. All classes of roads can be treated, from minor access roads to state highways. To date approximately 90 road embankment failures have been repaired with this technique.
The construction and maintenance of roads in mountainous terrain has always been a challenge to road builders and road managers. Generally the road would have been constructed as a sideling cut and fill, with the material cut from the hill slope being used to build up the required formation width as a sideling fill.