Investigating the effect of seasonal variations and drainage on structural numbers of bituminous pavements
Abstract
Ministry of Works and Transport (MoWT) through the Uganda Road Fund has endeavoured to carry out road maintenance with funds being allocated for road maintenance. As a result, the percentage of paved national roads in fair to good condition has improved from 74% to 80% from 2011 to 2017. The road sector was awarded the biggest share of 14% in the FY 2016/17 and FY 2021/22 making a total of UGX 441.79 billion which was awarded to KCCA, funded by both the Government of the Republic of Uganda and development partners. However, many of the roads constructed during the last 5 years have not yet shown visible signs of deterioration although it is advisable to apply some minimal maintenance for the road assets to last their design life. Even if no visible deterioration of a pavement takes place, its strength still changes during the course of a year due to climatic effects. It is important to understand how the strength of the bituminous roads in Kampala deteriorates annually, especially as a result of fatigue or structural cracking, to enable timely planning of maintenance strategies during their design lives. This research was carried out to investigate the effect of seasonal variations and drainage effects on structural numbers of bituminous pavements. Field observations were carried out manually for two weeks by use of checklists to determine the status of different drains. A large amount of secondary data and information was collected, reviewed and analyzed to determine the relationship between drainage, seasonality, and the structural numbers of bituminous pavements. Y.Wang,X.Xu,M.Zhang,S.Tao, and X.Li ( 2017) For paved roads in good, fair, poor and bad condition on KCCA paved road network; the pavement structural numbers decreased by 0.11, 0.13, 0.15 and 0.17 respectively for every additional wet month. If a bituminous road was newly built with an SNP of 3.25, but with a road side drainage in bad condition such as Kisota and Hoima-Kasubi road, it would take only 1 year and 7 months for the road to fail. For a road side drainage in poor condition such as Old Kira and Kisuule road, it would take only I year and 10 months and that in a fair drainage condition, it only would take 2 years and 1 month. For a road side drainage in good condition such as Kireka-Biira and Kulambiro road, it would only take 2 years and 6 months. Since the pavement strength decrease is more acute for roads in poor road drainage condition compared to those in excellent/good drainage condition, there is need to ensure that the paved road network is maintained in fair to good road drainage condition to enable the pavement last the duration of its design life
Key words
Seasonal Variation and Drainage Structural Numbers of Bituminous Pavements