Question

The design speed for a two-lane road is 80 kmph. When a design vehicle with a wheelbase of 6.6 m is negotiating a horizontal curve on the road, the off-tracking is measured as 0.096 m. The required widening of carriageway of the two-lane road on the curve is approximately:

• A. $0.55m$
• B. $0.85m$
• C. $0.75m$
• D. $0.65m$

Answer 1

The correct option is C $0.75m$

Off-tracking,
$\frac{l^2}{2R}=0.096m$

$\Rightarrow R=\frac{(6.6{)}^2}{2\times 0.096}=226.875m$

Extra widening,
$E_w=n\times \frac{l^2}{2R}+\frac{V}{9.5\sqrt{R}}$

$=2\times 0.096+\frac{80}{9.5\sqrt{226.875}}$

$=0.192+0.56=0.752m$