According to the Indian Road Congress guidelines, what is the value of the height of driver’s eye above road surface?
- A1.0 m
- B1.2 mCorrect
- C1.4 m
- D1.6 m
Solution
Concept
Driver's Eye Height
Formula
No direct formula exists; it is an empirical standard specified by Indian Road Congress (IRC) guidelines, used as a constant in sight distance calculations (such as SSD and OSD).
Step-by-step solution
1. Recall the Indian Road Congress (IRC) standard specifications for geometric design of highways. 2. Note that IRC specifies the standard height of the driver's eye above the road surface as 1.2 m. 3. Select Option B (1.2 m).
Explanation
According to the Indian Road Congress (IRC) guidelines, 1.2 m is the standard assumed height of a driver's eye above the road surface for calculating sight distances, such as stopping sight distance and overtaking sight distance, ensuring safe visibility on roads.
Shortcut
Remember 1.2 m using the phrase: Eye level at 1 point 2 meters (or picture a driver sitting at roughly 1.2 m height).
Common mistake
A common mistake is confusing the driver's eye height (1.2 m) with the AASHTO standard value (1.08 m, often misremembered as 1.0 m) or confusing it with the height of the headlight/obstacle.
Correct answer: B) 1.2 m