The Effect of Poor Surface Drainage Structure on Pavement Performance - A Case Study

In the design and construction of highways due consideration of drainage is a necessity to keep our roads performance satisfactory. Especially these days, due to the ever growing urbanization and extreme climatic changes, existing drainage structures are becoming incapable of accommodation the runoff that they are experiencing. In our country as well, there are a lot of problems related to drainage systems. Mizan is the major victim of this problem. Nevertheless, sufficient scientific researches that treat this issue were not conducted and thus sustainable solutions have not been given to the citys roads. This study was conducted in Mizan specifically along stadium to Telecommunication road in which the road is known for discomfort and unsafe riding surface due to over flooding and pounding of water on the surface of pavement. This research was aimed to investigate the causes of this poor surface drainage and its impact on pavements performance. In order to attain this general objective, the researcher initially investigated the factors for the poor surface drainage such as; cross slope and amount run off and then the effects that this poor drainage impose on the structural as well as functional performances of the pavement. The process of data collection included both the primary data sources through site survey, roughness test using Roughometer III, deflection tests using Benkelman beam, questioners and secondary data sources using topographic map. From the results the road in both right and left sides didnt attain the minimum value of cross slope for adequate drainage which is 2.5 % and the other factor is the actual amount of runoff is much greater than the designed one. This factor come up with high value of IRI for the right and left side of the road and also the value of mean RRD for the road is 0.95mm. From this stand point it can be concluded that drainage condition has strong relationship with the structural and functional inadequacy of pavements as well as on intensities of distresses. In order to alleviate this problem it is recommended to provide appropriate cross slope and drainage structure and also maintenance and re construction options.