Question

A priority intersection has a single-lane one-way traffic road crossing an undivided two-lane two-way traffic road. The traffic stream speed on the single-lane road is $20kmph$ and the speed on the two-lane road is $50kmph$. The perception-reaction time is $2.5s$, coefficient of longitudinal friction is $0.38$ and acceleration due to gravity is $9.81m/s^2$. A clear sight triangle has to be ensured at this intersection. The minimum lengths of the sides of the sight triangle along the two-lane road and the single-lane road, respectively will be

• A. $50m$ and $20m$
• B. $122m$ and $36m$
• C. $61m$ and $18m$
• D. $111m$ and $15m$

Answer 1

The correct option is D $111m$ and $15m$

As per data given and based on calculation of SSD the answer would be 61 m and 18 m. But, as per the code IRC:66 of sight distance calculation at priority intersection should be formed by measuring a distance of 15 m along minor roads and a distance equal to 8 seconds travel at the design speed.
($50\times 0.278\times 8=111m$) along the major road. Hence, answer will be 111 m and 15 m.