Design of traffic signals - Problems

PROBLEMS ON THE DESIGN OF TRAFFIC SIGNALS

1.    Given:

• Cycle time at an intersection = 60 s     
• Green time for a phase  =  27 s
• Yellow time  =  4 s 
• Saturation headway = 2.4 s/vehicle
• Start-up time lost  =  2 s/phase
• Clearance lost time  =  1 s/phase

Calculate the capacity of movement per lane

2.    In a right angled intersection of two roads, one road has four lanes with a total width of 12 m. The other road has two lanes with a total width of 6.6 m. The traffic volume of two approaching roads is 900 and 743 PCU per hour. Design the signal timing as per IRC guidelines

3.    The average speed on a roadway is 80 kmph. Under stopped conditions, the average spacing between vehicles is 6.9m. Determine the maximum flow of vehicles (road capacity)

4.    Fifteen minute traffic count on cross roads A and B during peak hour are observed as 178 and 142 vehicles per lane respectively approaching the intersection in the observed direction of heavier traffic flow. If the amber times required are 3 and 2 seconds respectively for two loads based on approach speeds, design the signal timings by trial cycle method assuming an average headway time of 2.5 seconds during green phase.

5.    The average normal flow of traffic on cross-roads A and B during design period are 400 and 250 PCU per hour. The saturation flow values on these roads are 1250 and 1000 PCU respectively. The all-red time required for pedestrian crossing is 12 seconds. Design the traffic signal by webster's method