CSI model for estimating road maintenance projects

Major road maintenance projects need an accurate cost estimate at the early stage of design. At present, simple and quick models are lacking. Two easy-to-use cost models for major asphalt road maintenance projects are developed. The double mean model and the trend line model are based on the cost-significance method. The historical data used are bills of quantities (BoQs) of major road maintenance projects including reconstruction, overlay and resurfacing. The cost-significant items in the models are consistent for this type of project. Further BoQs are used to test the accuracy of the cost-significance models. The two cost-significance models simplify the data collection and cost modelling process. The double mean model is suitable for quick estimates at scheme design stage, while the trend line model has a much better accuracy and is still simpler than traditional methods, and is therefore appropriate to use for the detailed design stage. Because there are fewer items whose costs require estimating, it is likely that the cost of each item can be estimated more accurately.