GATE 2024 CE (CE1) – Question 64
The following data is obtained from an axle load survey at a site:
Average rear axle load = 12000 kg
Number of commercial vehicles = 800 per day
The pavement at this site would be reconstructed over a period of 5 years from the date of survey. The design life of the reconstructed pavement is 15 years. Use the standard axle load as 8160 kg and the annual average vehicle growth rate as 4.0%. Assume that Equivalent Wheel Load Factor (EWLF) and Vehicle Damage Factor (VDF) are equal.
The cumulative standard axle (in msa) for the pavement design is ____________ (rounded off to 2 decimal places).
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Correct answer: 33.10 to 33.44
Explanation
The traffic when the new pavement opens, 5 years after the survey, is $A = 800(1.04)^5 = 973.3$ vehicles per day. The cumulative number of commercial vehicles over the 15-year design life is $N = \frac{365A[(1 + r)^n - 1]}{r} = \frac{365 \times 973.3 \times (1.04^{15} - 1)}{0.04} = 7.114 \times 10^6$. The vehicle damage factor is the fourth power law: $VDF = \left(\frac{12000}{8160}\right)^4 = 4.677$. The cumulative standard axles are $7.114 \times 10^6 \times 4.677 = 33.27 \times 10^6$, which is 33.27 msa.