Derivation of SSD, ISD, and OSD - Transportation Engineering

I am Prathamesh Varma. Currently in 3rd year civil engineering.
This ppt shows how to derive the stopping sight, intermediate sight and overtaking sight distances with the help of beautiful graphics and comprehensive text.
Hope this helps.

1. Derivation of
SSD, ISD, and
OSD
BE21F01F060

2. Stopping sight distance
Absolute minimum/
non-passing
sight distance

3. SSD = Lag Distance + Stopping Distance

4. r
L = v.t
L
Lag/ Reaction distance
t = Reaction time of Driver
v = Initial velocity of vehicle
r

5. Stopping distance
Kinetic energy of moving vehicle
=
Work done against friction for
stopping

6. Kinetic energy of moving vehicle
=
Work done against friction for
stopping
1 m.v
-
2
2
= F.L
s

7. SSD = v.t + v
r
2
-
2gf
--
SSD = Lag Distance + Stopping Distance
All values to be put in this formula are in SI i.e. meter and
second units

8. Stopping distance at slopes
Ascending gradient: +n%
1 m.v
-
2
2
= F.L
s
Equating kinetic energy and Work done
1 W.v
-
2
2
=
L
s
-
g
(fW + Wn)
-
100
= v
2
L
s
2
g(f + n)
-
100
(meters)

9. 1 W.v
-
2
= v
2
L
s
2
g(f - n)
-
100
Stopping distance at slopes
Descending gradient: -n%
1 m.v
-
2
2
= F.L
s
Equating kinetic energy and Work done
2
=
L
s
-
g
(fW - Wn)
-
100
(meters)

10. In roads with restricted width or in single lane roads
when two-way traffic is permitted, the minimum stopping
sight distance should be equal to twice the stopping
distance to enable both vehicle coming from opposite
directions to stop.
ISD = 2.SSD

11. safe Overtaking/ passing sight distance
A A A

12. OSD = d + d + d
1 2 3
d1 = V. t
b r
d2 = b + 2s
b = V .T
b
T - Overtaking time
s = 0.7V + 6
b
6m is standard
length of car
Empirical formula
given by IRC
d3 = V .T
c
Vc can be assumed equal to Va
which can be assumed equal
to Vd i.e design speed
t = 2sec
r
s - Space headway

13. OSD = d + d + d
1 2 3
OSD = V.t
b r
V .T
b
+ + 2(0.7V +6)
b
V.T
a
+
d1 = V. t
b r
d2 = b + 2s
d3 = V .T
c
T = 4s/a

14. Thanks For Riding Along!