Highway Development and Management Model – 4 (Hdm-4) Calibration (Addis Ababa – Modjo Trunk Road Case)

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Addis Ababa University


The Highway Development and Management Tools collectively referred to as HDM-4, developed by the World Bank, incorporates various applications. Some of the are: road performance prediction, road treatment programming, funding estimates, budget allocation, project appraisal, policy impact studies, and a wide range of special applications. This model is universally applicable given calibrated and has been adopted by many countries in the tropic and all over the world. This unanimous adoptability is true through, local adjustment as per the prevailing condition of the location or the country at which it is going to be used. Our country, Ethiopia, as one of the countries using this software for project level analysis and especially for economic feasibility analyses, it is noteworthy to know how dependable the software outputs are. In addition, rather than adopting default values, there were no properly documented calibration and validation of the software for Ethiopia so far. These reasons derive and motivate this research to be conducted. This study is focused on four Road Deterioration and Work Effects (RDWE) models calibrations, namely; roughness – age – environment factor (Kgm), crack initiation factor (Kcia), crack progression factor (Kcp), and general roughness progression factor (Kgp). This paper confirmed that there is discrepancy between the actual observed pavement distress values and the model predictions which indicate the need for calibration. Then, according to HDM-4’s calibration techniques, the result showed that the magnitude of roughness increment observed is lower than the default HDM-4’s prediction (1.00 for each factors), with Kgm=0.85. Also, the pavement cracks initiate earlier and progress faster than the one estimated by non – calibrated HDM-4 models, Kcia=0.67 & Kgp=1.49. Moreover, the general roughness progression adjustment factor turns out to be approximately a unit (Kgp=1.03) indicating no need of executing it if the other parameters are already adjusted. This mans, project costs estimated by non-calibrated software are generally over estimated by the environmental effects but the other three models of crack and general roughness under estimate project costs.



Road and Transport Engineering