Question

The traffic studies and axle load distribution studies carried out during project preparation showed that there are 5500 commercial vehicles per day with rear axle loads are in the range of 2500 to 3500 kg and growth rate of 6.5% per annum. The road is expected to be constructed in a period of 3 years after this study and the flexible pavement structure is to be designed for a life of 15 years. The commercial standard axle value will be
[Take lane distribution factor as 1]

• A. 2.01 msa
• B. 1.73 msa
• C. 1.17 msa
• D. 1.05 msa

Answer 1

The correct option is D 1.05 msa

Given:
$A=5500\text{vehicles,}r=6.5\%\text{per annum}$
$\text{construction period}=3years$

Traffic flow after 3 year
$=5500\times {(1+\frac{6.5}{100})}^3=6643.72cvpd$
$\simeq 6644cvpd$

$VDF={\left(\frac{L}{L_s}\right)}^4={\left[\frac{3000}{8160}\right]}^4=0.018$
$whereL=\frac{2500+3500}{2}=3000kg$

$\text{Equivalent axle load}=365\times 6643.72\times \frac{\left[\right(1+0.065{)}^{15}-1]}{\left(\frac{6.5}{100}\right)}\times 0.018\times 1$
$=1.05msa$