Traffic loading correlation with the magnitude and rate of change of fatigue crack growth

Abstract

The study investigated traffic loading correlation with magnitude and rate of fatigue crack growth on a section of the Northern Corridor Route in Uganda. The objectives of the study were (i) characterizing fatigue crack behaviour and traffic loading on the study road, (ii) establishing the trends in the rate of change of fatigue crack geometry propagation and (iii) developing a maintenance regime based on fatigue crack propagation. Seven study sections were carefully selected and marked out between Magamaga and Kakira on the selected highway. Three rounds of measurement of crack geometry (width, length and cracked block area) were taken using a digital vernier caliper and tape measure. Traffic surveys for a duration of one and a half years (18 months) from September 2017 to February 2019 were conducted. The results showed that the Kakira (West) bound lane was more heavily loaded than the Magamaga (East) bound lane. Statistical analysis revealed that the selected road section, data collection period and traffic direction were significant at a 0.05 level. There was a reducing trend in the percentage rate of change of crack geometry propagation i.e., crack width (57.27%), crack length (48.85%) and cracked block area (15.70%) during the study period. A maintenance regime based on the percentage rate of change of crack geometry per annum was developed whereby the duration to maintenance can be determined based on crack geometric parameters. The developed pavement maintenance regime can be used by the various agencies such as Ministry of Works and Transport (MoWT), Uganda National |Roads Authority (UNRA), Urban authorities such as Kampala Capital City Authority (KCCA), District Local Governments (DLGs), etc., to scientifically determine the duration to maintenance of their pavements. The agencies are recommended to invest in similar studies on their road networks to be able to get their specific road network input parameters. Additional research needs to be carried out on other pavements of varied thickness and traffic loading. The effect of climatic/environmental factors (temperature and rainfall) and geographical locations can also be studied.