Why this topic is important for ECET?
Highway Geometrics form the foundation of Transportation Engineering, dealing with the visible and invisible elements of road design – width, curves, gradients, sight distances, and super-elevation. In ECET 2026 Civil, you can expect direct formula-based problems and conceptual MCQs from this topic. Mastering highway geometrics ensures you score quick, error-free marks.
📘 Concept Notes
1. Highway Geometric Design
It deals with the visible features of a highway that affect safety, comfort, and speed. Elements include:
- Sight distance
- Horizontal curves
- Vertical curves
- Super-elevation
- Road widths, shoulders, medians
2. Sight Distance
- Distance visible to driver at any instant.
- Types:
- Stopping Sight Distance (SSD): Minimum distance needed to stop vehicle safely.
- Overtaking Sight Distance (OSD): Minimum distance required for overtaking on two-lane roads.
- Intermediate Sight Distance (ISD): 2 × SSD.
SSD Formula:
where
vvv = speed (m/s),
ttt = reaction time (2.5 sec standard),
ggg = gravity (9.81 m/s²),
fff = coefficient of friction.
3. Super-Elevation (e)
- Provided on horizontal curves to counteract centrifugal force.
where
vvv = speed (m/s),
RRR = radius of curve.
4. Extra Widening on Curves
Extra widening = Mechanical + Psychological widening.
where
nnn = lanes,
lll = wheelbase,
RRR = radius,
VVV = speed in kmph.
5. Transition Curve
- Gradually introduces curvature.
- Length of transition curve (L):
where
CCC = rate of change of centrifugal acceleration.
6. Gradients
- Slope of road surface.
- Types: ruling, limiting, exceptional.
7. Vertical Curves
- Connect different gradients smoothly.
- Summit curve length (L):
(approximation for SSD consideration) - Valley curve length (L):
⚙️ Formulas
🔟 10 MCQs
Q1. Stopping sight distance depends on:
a) Speed only
b) Speed and reaction time
c) Speed, friction, gradient
d) All of the above
Q2. For design, standard reaction time taken =
a) 1 sec
b) 2.5 sec
c) 4 sec
d) 5 sec
Q3. A vehicle at 72 kmph stops in 6 sec. Approximate SSD = ?
a) 50 m
b) 120 m
c) 80 m
d) 150 m
Q4. Formula for super-elevation is:
a) 
b)
c) 
d) 
Q5. Maximum super-elevation in India as per IRC is:
a) 1 in 8
b) 1 in 12
c) 1 in 15
d) 1 in 16
Q6. Extra widening on curves consists of:
a) Mechanical only
b) Psychological only
c) Both mechanical and psychological
d) None
Q7. Transition curve is introduced to:
a) Reduce shock and sway
b) Introduce centrifugal force gradually
c) Provide comfort and safety
d) All of the above
Q8. For summit curves, the main criterion is:
a) Comfort
b) Overtaking sight distance
c) Stopping sight distance
d) Aesthetics
Q9. At design speed of 60 kmph, radius of horizontal curve = 200 m, find required e+f.
a) 0.05
b) 0.09
c) 0.12
d) 0.2
Q10. IRC recommended ruling gradient in plain terrain =
a) 1 in 15
b) 1 in 20
c) 1 in 30
d) 1 in 40
✅ Answer Key
| Q | Answer |
|---|---|
| 1 | d |
| 2 | b |
| 3 | c |
| 4 | b |
| 5 | d |
| 6 | c |
| 7 | d |
| 8 | c |
| 9 | b |
| 10 | b |
🧠 Explanations
- Q1: SSD depends on all factors (speed, reaction time, gradient, friction) → (d).
- Q2: IRC recommends 2.5 sec reaction time → (b).
- Q3: v = 72 kmph = 20 m/s, SSD = vt = 20×6 = 120 m → (c).
- Q4: Correct formula is
→ (b). - Q5: IRC max = 1/15 = 0.067 → (d).
- Q6: Extra widening = mechanical + psychological → (c).
- Q7: Transition curve ensures comfort, safety, gradual centrifugal force → (d).
- Q8: Summit curve is designed for SSD → (c).
- Q9: v = 16.67 m/s, (v²/gR) = (278)/1962 ≈ 0.09 → (b).
- Q10: Ruling gradient in plains = 1 in 30, but limiting = 1 in 20 → (b).
🎯 Motivation / Why Practice Matters
Highway Geometrics is a direct scoring topic in ECET 2026 Civil.
- Most questions are formula-based – quick to solve if you memorize relations.
- Mistakes usually come from unit conversion and IRC values.
👉 Practice daily to ensure speed + accuracy, giving you an edge in competitive ranking.
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