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Pavement maintenance is crucial and integral part of the service life of a pavement. Pavement cannot simply be subjected to fully pre-planned maintenance schedule activities. A good pavement management practice should depend on performance evaluation to set benchmarks and decide on which improvement are priorities at given time.
This study aimed at developing a pavement condition evaluation system for flexible pavement for Zanzibar roads. The study consists of three tasks, the first covered assessment of pavement condition evaluation practice in Zanzibar agency, the second task was to develop pavement condition prediction model to predict flexible pavement whereas the third task was to develop a pavement condition evaluation system for flexible pavement in Zanzibar. As a case study, six roads were selected for observation and field measurement.
Through an assessment of current pavement condition evaluation practice, the study found that ZANROADS did not have a standardized pavement condition evaluation system instead a manual method used for data collection. Distress and roughness survey were found to be major types of condition surveys carried by the agency.
Through pavement observation, field measurement and extraction of data from the RMMS database, eight types of surface distress were identified and represented in terms of the international roughness index (IRI).
Pavement condition prediction models were developed for selected roads namely Jang’ombe road, Chwaka road, Paje and Nungwi road in the Zanzibar Road Network.
Three (3) independent variables (pavement age, routine maintenance and traffic loading) were used in developed models to predict IRI. Results indicated that pavement age, routine maintenance and traffic loading affected dependent variable IRI, at 0.05 significant level for selected roads. The developed model equations were validated by comparing predicted vs actual IRI(m/km). The models were found to be statistically suitable for use.
Systematic, and yet simple and easy to understand procedures that is flexible enough for use in a variety of situations has been developed based on objective No I and II. The developed system is good (provides a step by step frame work) as a general particular guide, a particularly for young high way engineers. Also, since limited funds are provided for maintenance work, the evaluation system developed can help in prioritizing the process and selecting the best rehabilitation/maintenance strategy in flexible pavement. |
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