Investigating the effect of traffic loading on the riding quality on the selected roads in Kampala

Abstract

Over the last years, Government of Uganda has undertaken huge infrastructural developments in the Country and for Kampala Capital City Authority (KCCA), government has implemented a number of programs/projects in the City including the KIIDP1 and KIIDP2. Currently, Kampala has a road network of 2,100Km of which 642Km is paved with a drainage system of 145 Km of major drains and 3,428Km of minor drains; of these only 714Km (20%) are constructed open drains. Government is aware of the state of deteriorated road network in the city arising from an old network which has outlived its design life exhibiting potholes and edge distress. The up-to-date information of traffic types on Ugandan roads grows at a rate of 18.1% per annum with vehicle composition ranging from small saloon cars of two axles to heavy trucks of 5+ axles (UNBS, 2014). Kampala Capital City Authority has formulated laws and restrictions to limit excessive axle loading on the pavements in Kampala but few studies have been carried out to assess the impact of exceeding traffic loading limits leading to limited pavement performance hence poor riding quality. The research was carried out purposely to investigate the impact of exceeding Axle Load limits on the riding quality of the pavements selected.The traffic data for Bombo,Sir Apollo Kagwa and Gayaza roads were collected by manual counts using the manual traffic counts tally sheets. This exercise was conducted for seven days on each road. The traffic data showed changes in traffic volumes as well as the traffic while showing a drastic increase in the traffic volumes of each road in 2022 compared to the 2021 and 2020 traffic data. The study also established the Present Serviceability Index values of the study roads which were calculated using the design life and the number of years each road has spent. The study also established a relationship between Traffic volumes (MESALs) and the Present Serviceability Index Values of each of the roads.