Friday, August 30, 2013

Sight Distance - Stopping Sight Distance and Overtaking Sight Distance


Sight Distance:
It is the length of the road ahead visible to a driver at any instance. IRC (Indian Roads congress) has standardized the definition by assuming the eye level of driver as 1.2 m above the road surface and height of obstruction 0.15 m from the road surface.

These are the three main types of sight distances, that are considered while the design of the roads:
(a) Stopping Sight Distance
(b) Overtaking Sight Distance
(c) Sight Distance at the Intersections

(a) Stopping Sight Distance: Stopping Sight Distance is the sight distance required for a driver to effectively apply the brakes and stop the vehicle without collision with the obstruction on the road.
  Stopping Sight Distance = Lag Distance + Braking Distance = v.t + v^2/2gf   where, v is in m/sec

(b) Overtaking Sight Distance: Overtaking Sight Distance is the sight distance which is required by the vehicle running at the design speed to overtake a vehicle running in the same lane at relatively smaller speed.

OSD = d1+ d2+ d3 = vb.t + vb.T + 2S + v.T      

(c) Sight Distance at the Intersection: Sight distance on the uncontrolled intersections should be sufficient enough  for the safety of the traffic, it should be at least equal to the stopping sight distance. 

thanks for visit!

Sand Cone Method to Determine Density - A solved Example

Hi, This problem deals with the Sand Cone Test used to determine the density of the compacted soil. Problem: A sand cone density test w...