Concept explainers
Effectof cycle length when saturation flow rates at
Answer to Problem 17P
Explanation of Solution
Given information:
Repeat
Shows a detailed layout of the phasing system and the intersection geometry used.
Calculation:
Equivalent hourly flow for north approach at left turn is given by,
Equivalent hourly flow
Peak hour volume
Peak hour factor
Substitute the values in equation
Calculate for other approaches like left turn, right turn and through movement in
Approach | North | South | East | East |
Left turn | ||||
Through movement | ||||
Right turn |
Calculate the critical volume for other approaches like left turn, right turn and through movement in
Left to north approach is left turn is
Through movement is
Approach | North | South | East | East |
Left turn | ||||
Through movement |
For the saturation flow rates at
Similarly calculate the saturation flow rates for other approaches in
Approach | saturation flow rates,
|
Through lanes | |
Through right lanes | |
Left lanes | |
Left through lanes | |
Left through right lanes |
Maximum value of the ratios of approach flow using formula,
Maximum value of ratios of approach flow to saturation flow to all lanes
Flow on lane groups
Saturation flow on lane group
Substitute the values in equation
Calculate for other
Approach | Phase | Phase | Phase | Phase |
Sum of critical ratio is given by,
Total lost time is given by,
Total lost time
Number of phases
Lost time for phase
Total all red time
Substitute the values in equation
Cycle length is given by,
Total effective green time is given by,
Allocated green time for phase
Allocated green time for other phases is given in the table
Phase | Allocated green time in sec |
Minimum green time for phase
Crosswalk length
Average speed of pedestrians
Number of pedestrians crossing during an interval
Substitute the values in equation
Minimum Green time for other phases is given Table
Phase | Minimum green time in sec |
From the Table
Sum of green and yellow time is given by,
Total cycle length is given by,
Conclusion:
Therefore by increasingsaturation flow rates at
Want to see more full solutions like this?
Chapter 8 Solutions
Traffic And Highway Engineering
- Subject: transportation engineering Read the question carefully and give me right solution according to the question. A signal has four phases, where the critical lane group flow ratios are 0.115, 0.204, 0.099, and 0.248. If the lost time per phase is 6 seconds and the critical intersection v/c ratio is 0.88, calculate the minimum cycle length and the phase effective green times such that the lane group v/c ratios are equal.arrow_forwardCompute the rate of flow in veh/hr if the space mean speed is 35 mph and the density of traffic is 17 veh/km.arrow_forwardThe following calculations are taken at the approach of an intersection during the morning rush hour. Determine (a) the hourly volume, (b) the peak flow rate in one hour, and (c) the peak hour factor.arrow_forward
- TRANSPORTATION ENGINNERING-TRAFFIC SIGNALS An approach to a predetermined signal has 25 seconds of effective green for a 60 second cycle. The approach volume is 500 vehicles/hour and the saturation flow rate is 1400 vehicles/hour. Calculate the average vehicle delay using D/D/1 queing.arrow_forwardQuest... In a three-phase signal system design for a four- leg intersection, the critical flow ratios for each phase are 0.18, 0.32, and 0.22. The total loss time in each of the phases is 2 s. As per Webster's formula, find the optimal cycle length.arrow_forwardThe equivalent hourly flow rate for an approach with 125 vehicles in the peak 15 minutes and PHF = 0.92 would be:arrow_forward
- For two circulating lane, Conflicting flow rate of 675 pc/hr . find total entry lane capacity.arrow_forwardGiven a Greenshields linear density-speed relationship of us = 71.2 - 0.584k a. derive the flow-speed relationship equation b. Derive the flow-density relationship equation c. Find the mean free flow speed d. Find the jam density e.Find the capacityarrow_forwardQ3b. The 15km Atta Mills road connecting Old Barrier to Kokrobite operates with a capacity of 2250 pcu/hr and can be traversed within 15 minutes under free flow conditions. If a flow of 3100 pcu/hr is assigned to the road based on the capacity-restrained approach, what would be the resultant travel time after the traffic assignment proce ss.arrow_forward
- Traffic and Highway EngineeringCivil EngineeringISBN:9781305156241Author:Garber, Nicholas J.Publisher:Cengage Learning