High rainfall leads to flood vulnerability and potentially leads to the failure of road pavement which affects the economic loss for the people. However, such road pavement failures need to be studied more deeply to be able to distinguish whether the failure is solely due to flood natural disaster or other factors, such as overloading and poor construction quality. This research is urgently needed because up to now there is no tool for assessing pavement failure as a tool of decision-making system that is able to distinguish road pavement failure causal factors into category of natural disaster or human negligence factors in accordance with the definition of building failure in Indonesia Law no. 2 year 2017. Assessment of the causal factor of failure is very important because it is closely related to the determination of the parties who must be legally responsible. This research intends to develop methods for assessing the damage and failure of pavement as a tool of rapid and accurate decision-making system to determine the factors of pavement failure. To obtain accurate results, a case study was taken on Kendal Timur road to enable a deep evaluation of the factors that causing failure on the road. The results showed that many factors involved in causing the failure of the road, such as un-functional drainage channel, uncontrolled overload due to the closing of weigh stations around the road, and also low quality of road maintenance work so that repeating similar road damages occurred in the not-too-distant future. Based on functional and structural failure analysis, as much as 71%, 10% and 19% of the road were in failed, critical and not-failed conditions, respectively.