Design a pre-timed signal plan (phasing and timing) for the off-peak hour where the
volumes are 50% of the value shown in Figure 1 (e.g. Northbound through is just 170
instead of 340 vehicles per hour)
Assume the following saturation flows
• Saturation flows for protected and split left turn phasing is 1,700 veh/hr/ln
• Saturation flows for single thru/right shared lanes is 1750 veh/hr/ln
• Saturation flows for thru + thru/right shared lanes is 3300 veh/hr (2 lanes)
Clearly show your thinking and any assumption that you are making. Highlight or box answers and results.
1. What phasing plan do you propose? Do not take into account pedestrian crossing times.
2. Determine all g, G, R, Y, R, AR values. Do not take into account pedestrian crossing times.
3. Create dilemma zone graphs for 65 mph and 55 mph speeds and with the distances shown in Figure 1. Analyze the dilemma zone problem and take into account that Y cannot exceed 5 seconds and that AR cannot exceed 2 seconds.
4. Think about the dilemma zone for bicycles taking into account that bicycle speed is 10 mph and that bicycle deceleration rate is 8 ft/sec2 . Cyclists' reaction time is 1 second. Can you have Y and/or AR values that eliminate the dilemma zone for cyclists? Create dilemma zone graphs for cyclists. Can you make Y and AR times work for both automobiles and cyclists?
5. Take into account pedestrian crossing times. What phasing and signal timing do you propose (assume an urban area with a lot of pedestrians)? What phasing and signal timing do you propose, what type of traffic signal or additional devices for control and/or detection (assume a suburban area with very few pedestrians)?
