42.6. Problems

Try these first

1. 1.

   What is the lost time per phase?

   Hint

   Refer to the data provided in the problem.

2. 2.

   Define cycle length.

   Hint

   Think about what 'complete' means in this context.

3. 3.

   What does the term 'cycle length' refer to?

   • Time for a complete traffic signal sequence
   • Duration of green light only
   • Amber light duration

   Hint

   Consider all phases involved in a signal operation.

4. 4.

   True or False: Lost time affects the actual green time available.

   • True
   • False

   Hint

   Think about how signals operate during transitions.

5. 5.

   A four-legged intersection with different flows of traffic needs to determine an efficient cycle length. If traffic is consistently high and flows are 800 vph (North-South) and 600 vph (East-West), what would be the optimal cycle length considering a lost time of 2.5 seconds and a V/C ratio of 0.9?

   Hint

   Mind the saturation flow and adjust your calculations accordingly.

6. 6.

   With given traffic flows of 750 vph (North-South) and 500 vph (East-West), what would the total delay be for one full cycle if the effective green time allocated is 18 seconds?

   Hint

   Focus on which values are needed from the relationships outlined with Webster’s Delay formula.