ADJUSTMENT OF THE CRACK FACTORS FOR HDM-4 DETERIORATION MODELTO ETHIOPIAN ASPHALT CONCRETE ROADS: ACASE STUDY ON ADAMAMETHARA ROAD
Creators: name: WONDEMAGEGN ZEWDIE TEKELE
Publisher: name: National Academic Digital Repository of Ethiopia
Year: 2020
Subjects: The Highway Development and Management Model (HDM), originally developed by the World Bank, has become widely used as a planning and programming tool for highway expenditures and maintenance standards. HDM is a computer model that simulates physical and economic conditions throughout the analysis. Transportation planners and engineers in Ethiopia are also using the Model for feasibility studies and pavement management purposes. The Link AdamaMetehara is serving the highest traffic volume and classified in the tropical Semi-Arid environmental classification. One of the sub-model incorporated in the software is the Road Deterioration and Work Effects (RDWE) containing key parameters like crack initiation and propagation factors which shall be adjusted to the specific conditions of the country where they are to be used. Poor deterioration modeling can result in making feasible projects infeasible and vice versa, resulting in wrong decision making and misleads the timely maintenance intervention plan which is largely been a problem in Ethiopia, and quite a great proportion of roads fail before the design period due to lack of timely maintenance measures hence huge mismanagement of public funds. Thus, to carry out the adjustment procedure, a pavement condition survey data is collected using standard statistical sampling techniques for the analysis years from the field survey and valid data from pertinent offices. The actual crack mapping, measuring and evaluation process is performed based on the crack measuring mechanisms recommended by the model and structured it using the British pavement surface condition rating manual. The method of adjustment for the crack factors between the forecasted and observed values is linear regression. Based on the equation given in HDM-4 the result found from the study shows that the user-specified adjustments to the cracking initiation factor Kci = 0.84 and for the crack propagation factor Kcp = 1.20. The influence of underestimated high traffic load on the pavement exposed fatigue cracking which demands adoption of several different growth rates based on short, medium, and long-term considerations since the indirect effect of cracking to asphalt roads is an important criterion to fail the road before the design period. Therefore, it is recommended to carry out post-evaluation study for each representative pavement type to study how well the pavement is performing and help to make well-informed decision optimizing capital costs and minimizing operating costs by employing preventive maintenances

description: The Highway Development and Management Model (HDM), originally developed by the World<br> Bank, has become widely used as a planning and programming tool for highway expenditures<br> and maintenance standards. HDM is a computer model that simulates physical and economic<br> conditions throughout the analysis. Transportation planners and engineers in Ethiopia are also<br> using the Model for feasibility studies and pavement management purposes. The Link AdamaMetehara is serving the highest traffic volume and classified in the tropical Semi-Arid<br> environmental classification. One of the sub-model incorporated in the software is the Road<br> Deterioration and Work Effects (RDWE) containing key parameters like crack initiation and<br> propagation factors which shall be adjusted to the specific conditions of the country where they<br> are to be used. Poor deterioration modeling can result in making feasible projects infeasible and<br> vice versa, resulting in wrong decision making and misleads the timely maintenance intervention<br> plan which is largely been a problem in Ethiopia, and quite a great proportion of roads fail<br> before the design period due to lack of timely maintenance measures hence huge<br> mismanagement of public funds. Thus, to carry out the adjustment procedure, a pavement<br> condition survey data is collected using standard statistical sampling techniques for the analysis<br> years from the field survey and valid data from pertinent offices. The actual crack mapping,<br> measuring and evaluation process is performed based on the crack measuring mechanisms<br> recommended by the model and structured it using the British pavement surface condition rating<br> manual. The method of adjustment for the crack factors between the forecasted and observed<br> values is linear regression. Based on the equation given in HDM-4 the result found from the<br> study shows that the user-specified adjustments to the cracking initiation factor Kci = 0.84 and<br> for the crack propagation factor Kcp = 1.20. The influence of underestimated high traffic load<br> on the pavement exposed fatigue cracking which demands adoption of several different growth<br> rates based on short, medium, and long-term considerations since the indirect effect of cracking<br> to asphalt roads is an important criterion to fail the road before the design period. Therefore, it<br> is recommended to carry out post-evaluation study for each representative pavement type to<br> study how well the pavement is performing and help to make well-informed decision, optimizing<br> capital costs and minimizing operating costs by employing preventive maintenances