Question

A minor road intersects a major 4-lane divided road with a design speed of 55mph and a median width of 8 feet. The intersection is controlled with a stop sign on the minor road. If the design vehicle is a passenger car, determine the minimum sight distance required on the major road that will allow a stopped vehicle on the minor road to safely turn left if the approach grade on the minor road is 3%.

Answer 1

The Design Speed =55 MPH(Miles per Hour)

1 miles per hour =0.447 meter pe second

then 55MPH=55*0.447=24.58 meter per second

Consider recation time =2.5 second

Consider Co efficinet friction is 0.35

As per the Stopping sight distance based on the Breaking distance+ Lag distance

SSD=Vt+(V^2/(2gf))

SSD=24.58+(24.58^2/(2*9.81*0.35))

The total stopping sight distance is =150 meters

if we consider the Approaching garde on the minor road is 3%

SSD=Vt+(V^2/(2g(f-n/100))

SSD=24.58+(24.58^2/(2*9.81*(0.35-3/100))

then stopping sight diatnce is =158 meters