Analysis of Incremental Load Damaging Effects of Overloaded Trucks on Federal Highway Pavement Structures in Nigeria

The study is to assess the present serviceability rating of Nigerian highways and the load damage effects of overloaded trucks. The researchers used the American Association of State Highway and Transportation Officials (AASHTO) methods. In this study, the highway section of Lokoja-Abuja, Ilorin-Jebba and Abakiliki-Ogoja via Mbok roads were selected, and data were collected through an axle-load survey, automatic traffic count and from secondary sources. The rate of gross vehicle weight violation was found, ranging from 20% to 94% of the axle load distribution across the studied network. Comparing the overloaded vehicle damage factor (V.D.F.) and standard V.D.F., the range was from 1.2 to 41.34 times across the road networks studied, and this explained why the pavement structures of Nigerian roads tend to deteriorate during its service life rapidly. Present serviceability rating was estimated at 3.45, 4.41 and 3.35 for Lokoja-Abuja, Ilorin-Jebba and Abakiliki-Ogoja roads respectively, showing depletion from their initial conditions. The damaging effects of the HGV are less severe at Lokoja-Abuja Road (with g = 0.30), followed by Ilorin-Jebba Road (with g = 0.35) and more in Abakiliki-Ogoja Road (with g = 0.43). The heaviest overload of 94% of the 6-axle vehicles plying at the Lokoja-Abuja road could explain this intense damaging effect on the road pavement