Estimation of the Impact of the Overloaded Truck on the Service Life of Pavement Structures in Nigeria

Abstract

Overloading by commercial trucks in Nigeria is a serious problem. The overloaded trucks stress the road structure beyond safe bearing capacity. Traffic load is a dominant function on pavement design because the main feature of pavement is to resist traffic load. In Nigeria, the percentage of overloaded trucks can reach more than 94% in the total number of vehicles and maybe one of the substantial factors that reduce the service life of the road pavements. This paper presents the analysis results of the weigh-in-motion survey data at Lokoja-Abuja in Nigeria and the impact of overloaded trucks on the pavement. For the analysis the simplified approach was used, the axle loads were converted into representative single-axle loads based on 4th power formula by AASHTO 1993 equation. The vehicle damage factor of vehicles is presented and was compared with the Highways National Standard to estimate the remaining service life of the pavement. The analysis showed that the vehicle damage factor determined from weigh-in-motion data is hugely higher than vehicle damage factor of the national standard in Nigeria which may lead to accelerated deterioration, reducing the service life of the pavement structures. From this result, we can conclude that there is a reduction in the service life of approximately about 10.48 years from the design life of the pavement. Which means the service life of the Lokoja-Abuja pavement designed for 15 years will start deterioration just after four years and six months of commissioning.