Question

A two lane single carriageway is to be designed for a design life period of 15 years. Total two way traffic intensity in the year of completion of construction is expected to be 2000 commercial vehicles per day. Vehicle damage factor = 3.0, Lane distribution factor = 0.75. Assuming an annual rate of traffic growth as 7.5% , the design traffic expressed as cumulative number of standard axles, is

• A. $22.6\times {10}^6$
• B. $5.3\times {10}^6$
• C. $42.9\times {10}^6$
• D. $10.1\times {10}^6$

Answer 1

The correct option is C $42.9\times {10}^6$

No. of standard axle in design life to be adopted for design is taken as

$N=\frac{365A(1+r{)}^n-1}{r}\times VDF\times LDF$

Where,
A = No. of commercial vehicle/day after end of construction
$A=P(1+r{)}^x$
P = No. of commercial vehicle per day at last count
r = Growth rate
x = Construction period in years
n = Design life in years
VDF = Vehicle damage factor
LDF = Lane distribution factor

Hence, From (1)
$N=\frac{365\times 2000\left[\right(1+0.075{)}^{15}-1]}{0.075}\times 3\times 0.75$
$=42.9\times {10}^6\text{standard axles}$