TRUCK LOADING PATTERN AND ITS IMPACT ON PAVEMENT DESIGN

Pakistan being a developing country, with many budget constraints, poor governance and legislation of commercial vehicle’s loading limits facing the dilemma of overloading of commercial vehicles from the last decade, as overloading is the main factor for pavement deteriorations. Highway authorities would be facing the serious problems of maintenance, rehabilitation and reconstruction of existing roads together with designing the future roads to meet the criteria for much higher traffic loadings. Thus, there is grim need to evaluate the impact of commercial vehicle’s overloading on pavement performance to come-up with the optimum solution. Data of three weigh in motion stations between the two major cities (Peshawar and Rawalpindi) on the main national highway N-5 of Pakistan were collected and analyzed. A comparative study of actual and design load equivalency factors (NTRC-1995) were carried to determine the impact of current loading pattern on the pavement performance. AASHTO flexible pavement design method was applied to compute the axle load equivalency factors and thicknesses required for pavement structures. Furthermore, the effect of variation in truck factor due to current loadings, on pavement design practice in Pakistan in term of performance period and economy was evaluated. It is found that, on average 90% of the commercial vehicles in Pakistan are going overloaded than the suggested limits with axle type-2 vehicle is more damaging to pavement structures having truck factors 2.65 times more than the design truck factors. Moreover, it was analyzed that the pavement structure designed on the basis of truck factors suggested by NTRC would get deteriorate in 3.5 years rather than 10 years with the economic loss of 4.5 million rupees approx. JOURNAL OF MECHANICS OF CONTINUA AND MATHEMATICAL SCIENCES www.journalimcms.org ISSN (Online) : 2454 -7190 Vol.-15, No.-3, March (2020) pp 238-255 ISSN (Print) 0973-8975 J. Mech. Cont.& Math. Sci., Vol.-15, No.-3, March (2020) pp 238-255 Copyright reserved © J. Mech. Cont.& Math. Sci. Kamran Aziz et al 239