# Geometric Design of Highway and Planning

 Question 1
As per the Indian Roads Congress guidelines (IRC 86: 2018), extra widening depends on which of the following parameters?
 A Horizontal curve radius B Superelevation C Number of lanes D Longitudinal gradient
GATE CE 2023 SET-2   Transportation Engineering
Question 1 Explanation:
As per IRC $86: 2018$ Clause 8.6 Widening of Carriageway on Curves:
At sharp horizontal curves, it is necessary to widen the carriageway to provide for safe passage of vehicles. The widening required has two components: (i) mechanical widening to components for the extra width occupied by a vehicle on the curve due to tracking of the rare wheels, and (ii) psychological widening to permit easy crossing of vehicles since vehicles in a lane tend to wander more on a curve than on a straight reach.
On two-lane or wider roads, it is necessary that both the above components should be fully catered for so that the lateral clearance between vehicles of curves is maintained equal to the clearance available on straight. Position of single-lane roads however is somewhat different.
Since during crossing maneuvers outer wheels of vehicles have in any case to use the shoulder whether on the straight or on the curve. It is, therefore sufficient on single lane roads if only the mechanical component of widening is taken into account.
Based on the above considerations, the extra width of carriageway to be provided at horizontal curves on single and two-lane roads is given in Table For multi-lane roads, the pavement widening may be calculated by adding half the widening for two-lane roads to each lane.
Table : Extra width of Pavement at Horizontal Curves

 Question 2
Which of the following is equal to the stopping sight distance?
 A (braking distance required to come to stop) + (distance travelled during the perception- reaction time) B (braking distance required to come to stop) - (distance travelled during the perception- reaction time) C (braking distance required to come to stop) D (distance travelled during the perception- reaction time)
GATE CE 2023 SET-2   Transportation Engineering
Question 2 Explanation:
SSD $=$ Braking distance + lag distance
where,
Braking distance $=$ Braking distance required to come to stop
Lag distance $=$ distance travelled during the perception reaction time.

 Question 3
For a horizontal curve, the radius of a circular curve is obtained as $300 \mathrm{~m}$ with the design speed as $15 \mathrm{~m} / \mathrm{s}$. If the allowable jerk is $0.75 \mathrm{~m} / \mathrm{s}^{3}$, what is the minimum length (in $\mathrm{m}$, in integer) of the transition curve ?
 A 5 B 10 C 15 D 25
GATE CE 2023 SET-1   Transportation Engineering
Question 3 Explanation:
Radius of circular curve $(\mathrm{R})=300 \mathrm{~m}$
$\mathrm{V}_{\mathrm{d}}=15 \mathrm{~m} / \mathrm{s}$
Allowable jerk $(\mathrm{C})=0.75 \mathrm{~m} / \mathrm{sec}^{3}$
\begin{aligned} & \mathrm{L}_{\min }=\frac{\mathrm{v}^{3}}{\mathrm{CR}} \\ & \mathrm{L}_{\min }=\frac{(15)^{3}}{0.75 \times(300)}=15 \mathrm{~m} \end{aligned}
$\therefore \quad$ Minimum length of transition curve $=15 \mathrm{~m}$.
 Question 4
$G_{1}$ and $G_{2}$ are the slopes of the approach and departure grades of a vertical curve, respectively.
Given $\left|G_{1}\right| \lt \left|G_{2}\right|$ and $\left|G_{1}\right| \neq\left|G_{2}\right| \neq 0$

Statement 1: $+G_{1}$ followed by $+G_{2}$ results in a sag vertical curve.
Statement 2: $-G_{1}$ followed by $-G_{2}$ results in a sag vertical curve.
Statement 3: $+G_{1}$ followed by $-G_{2}$ results in a crest vertical curve.

Which option amongst the following is true?
 A Statement 1 and Statement 3 are correct; Statement 2 is wrong B Statement 1 and Statement 2 are correct; Statement 3 is wrong C Statement 1 is correct; Statement 2 and Statement 3 are wrong D Statement 2 is correct; Statement 1 and Statement 3 are wrong
GATE CE 2023 SET-1   Transportation Engineering
Question 4 Explanation:
Given, $\left|G_{1}\right| \lt \left|G_{2}\right|$ and $\left|G_{1}\right| \neq\left|G_{2}\right| \neq 0$

Statement 1:

$\left|G_{1}\right| \lt \left|G_{2}\right|$
This results in a vertical sag curve.

Statement 2:

$\left|G_{1}\right| \lt \left|G_{2}\right|$
This results in a vertical crest curve.

Statement 3:

$\left|G_{1}\right| \lt \left|G_{2}\right|$
This results in a vertical crest curve.
 Question 5
A parabolic vertical crest curve connects two road segments with grades +1.0% and -2.0%. If a 200 m stopping sight distance is needed for a driver at a height of 1.2 m to avoid an obstacle of height 0.15 m, then the minimum curve length should be ______ m. (round off to the nearest integer)
 A 241 B 365 C 115 D 273
GATE CE 2022 SET-2   Transportation Engineering
Question 5 Explanation:
Given that, $n_1=+1%$ and $n_2=-2%$
$n=n_1-n_2=3%$
SSD = 200 m
and $h_1= 1.2 m$ and $h_2= 0.15 m$
as given $n_1$ up gradient, and $n_2$ - down gradient.
So curve is summit curve.
Assume L > SSD
\begin{aligned} L &=\frac{NS^2}{2(\sqrt{n_1}+\sqrt{n_2})^2} \\ &= \frac{3}{100} \times \frac{(200)^2}{2 \times (\sqrt{1.2}+\sqrt{0.15})^2}\\ &=272.91>200 \\ L&=272.91m \end{aligned}

There are 5 questions to complete.

### 4 thoughts on “Geometric Design of Highway and Planning”

1. Very helpful. Thanku so muchðŸ”¥

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2. Please check the solution of question 28
M= (R-d)-(R-d) cos a/2 For two lane

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3. You are wrong bro !
m= R-(R-d)cos(a/2)
solution is correct.

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4. Nice practice sets .. I found lot of problems.. related gate which helps me in exam

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