NIGERIAN BUILDING AND ROAD RESEARCH INSTITUTE
(Federal Ministry of Science, Innovations & Technology)
EFFECT OF AXLE LOADS ON PAVEMENT DETERIORATION: A CASE OF GOMBE-NUMAN EXPRESSWAY
AGBONKHESE, O.
Abstract
This paper presents the results of an investigation conducted on a section of the Gombe-Numan expressway to determine the effects of axle loads of overloaded vehicles on pavement deterioration. Metro Count RoadPod VT 5900, a traffic data analyst, was installed for seven days at the study area to capture classified traffic and axle load survey data for determining the Average daily traffic, ADT, percentage heavy vehicles and imposed axle load at respective axle position for each of the traversing vehicle.
The ARX vehicle classification scheme was utilized. Computation of the vehicle laden weight carried by each axle and the corresponding equivalent single axle load (ESAL) was achieved using the concept of Index Modeling. As an additional measure to the structural damaging effects of moving wheel loads on flexible pavements, the percentage and magnitude of overloaded axles were respectively determined. The results showed that the studied pavement was five times overstressed beyond the standard axle load, 80KN for Nigeria roads and a 35% rate of commercial vehicles causing structural damages to the pavement. This probably constitutes the experienced frequent structural damages to road pavements which have become typical of a developing country like Nigeria. For a more effective and proactive means of assuring the lifespan of pavements and asset value, it is recommended that weigh-in-motion, WIM bridges as well as complementary adequate barrier control of road access by the overloaded trucks be incorporated into strategic parts of the Nigerian road infrastructure and routine axle load surveys be implemented and practiced. Also, there should be a complete redesign of the chassis of heavy goods vehicles meant for developing countries like Nigeria.
Keywords: Axle load, ADT, Overloaded vehicle, Pavement, Traffic volume