The sum of the flow ratios for the critical lane group.
Answer to Problem 1P
The sum of the flow ratios for the critical lane group is
Explanation of Solution
Formula Used:
Write the expression for the flow ratio.
Here,
Write the expression to for the sum of flow ratio in the critical lane group.
Here,
Calculation:
Consider Phase
Calculate the flow ratio for Northbound Left(NBL).
Substitute
Calculate the flow ratio for Southbound Left(SBL).
Substitute
Maximum ratio of each phase is called as a critical lane group.
The critical lane group flow ratio for phase
Consider Phase
Calculate the flow ratio for Northbound Right Turn (NBL T/R).
Substitute
Calculate the flow ratio for Southbound Right Turn (SBL T/R).
Substitute
The critical lane group flow ratio for phase
Consider Phase
Calculate the flow ratio for Eastbound Left (EBL).
Substitute
Calculate the flow ratio for Westbound Left (WBL).
Substitute
Calculate the flow ratio for Eastbound Right Turn (EB T/R).
Substitute
Calculate the flow ratio for Westbound Right Turn (WB T/R).
Substitute
The critical lane group flow ratio for phase
Substitute
Conclusion:
The sum of the flow ratios for the critical lane group is
Want to see more full solutions like this?
Chapter 7 Solutions
Principles of Highway Engineering and Traffic Analysi (NEW!!)
- 1. An isolated intersection is controlled by a two-phase pre-timed signal with the movements allowed in each phases, and corresponding analysis and saturation flow rates shown in Table 1-1. Assume the start up loss time is 2 seconds per phase and the clearance loss time is 3 seconds per phase. The traffic flow accounts for the peak 15- min period and there is no initial queue at the start of analysis period. Progression adjustment factor PF=1.0. Please answer the following questions: (1) What are the optimal cycle length (round up to nearest 5 seconds) using Webster's optimum cycle length formula and effective green times (based on lane group v/c equalization)? (2) What is the northbound approach delay and level of service? Table 1-1 Phase and Flow Data for the Intersection Phase Allowed movements Analysis flow rate 1 2 NB T/R/L, SB T/R/L EB T/R/L, WB T/R/L Saturation flow rate 800, 820 2800, 2900 1120, 960 3000, 3200arrow_forwardAn intersection has a three-phase signal with the movements allowed in each phase and corresponding analysis and saturation flow rates shown in the table below. (1) Calculate the sum of the flow ratios for the critical lane groups. (2) calculate the minimum cycle length and the effective green time for each phase (balancing v/c for the critical lane groups). Assume the lost time is 4 seconds per phase and a critical intersection v/c of 0.90 is desired.arrow_forwardAn intersection has a three-phase signal with the movements allowed in each phase and corresponding analysis and saturation flow rates shown in the table below. Assume the lost time is 4 seconds per phase and a critical intersection v/c of 0.90 is desired. Phase 3 Allowed movements NB L, SB L NB T/R, SB T/R EB L, WB L EB T/R, WB T/R Analysis flow rate 330, 365 veh/h 1125, 1075 veh/h 110, 80 veh/h 250, 285 veh/h Saturation flow rate 1700, 1750 veh/h 3400, 3300 veh/h 650, 600 veh/h 1750, 1800 veh/h Using v/c equalization ratio, calculate the effective green time for phase 1 O 15.954 sec O 12.105 sec O 14.127 sec O 13.190 secarrow_forward
- Question-An isolated three-phase traffic signal is designed by webster's method. The critical flow ratio for three phases is 0.2, 0.3 and 0.25 respectively and lost time per phase is 4 second. Find the optimum cycle length (in sec.).arrow_forwardAn intersection has a three-phase signal with the movement allowed in each phase and corresponding analysis and saturation flow rates shown in the table below. Assume the lost time is 4 seconds per phase and a critical intersection v/c of 0.90 is desired Phase 1 2 3 Allowed Movement NB L, SB L NB T/R, SB T/R EB L, WB L EB /T/R, WB T/R Analysis Flow Rate 330, 365 veh/h 1125, 1075 veh/h 110, 80 veh/h 250, 285 veh/h Saturation Flow Rate 1700, 1750 veh/h 3400, 300 veh/h 650, 600 veh/h 1750, 1800 veh/h Calculate the Following: 1.)Sum of flow ratios for critical lane groups 2.)minimum cycle length 3.)using v/c equation ratio, calculate the effective green time for phase 1 4.)using v/c equation ratio, calculate the effective green time for phase 2 5.)using v/c equation ratio, calculate the effective green time for phase 3arrow_forwardThe minimum cycle length for an intersection is determined to be 95 seconds. The cirtical lane group flow ratios were calculated as 0.235, 0.250, 0.170 and 0.125 for phases 1- 4 respectively. What Xc was used in the determination of this cycle length, assuming a lost time of 5 seconds per phase?arrow_forward
- 5. Design signal timing for an intersection with the following details. Assume a total loss time of 3 seconds per phase. Width of lanes are 12 ft each. Assume that there are 20 pedestrians crossing each of the approaches per cycle. Check the signals for pedestrian crossing time. Take pedestrian walking speed as 4 ft/s. Saturation flow rates are: Left-turning: 1600 veh/hr/ln, Through: 1800 veh/hr/In, and Right- turning: 1700 veh/hr/In A 488 488 115 1051 217 N 338 -338 (В Phase I Phase II Phase III J!!! J↓↓ Yrarrow_forwardAn intersection has a three-phase signal with the movements allowed in each phase and corresponding analysis and saturation flow rates shown in the table below. Assume the lost time is 4 seconds per phase and a critical intersection v/c of 0.90 is desired. Phase Allowed movements NB L, SB L NB T/R, SB T/R EB L, WB L EB T/R, WB T/R Analysis flow rate 330, 365 veh/h 1125, 1075 veh/h 110, 80 veh/h 250, 285 veh/h Saturation flow rate 1700, 1750 veh/h 3400, 3300 veh/h 650, 600 veh/h 1750, 1800 veh/h Calculate the sum of the flow ratios for the critical lane groups. O 0.709 O 0.857 O 0.787 O 0.829arrow_forwardA signalized intersection operates in two phases. The lost time is 3 seconds per phase. The maximum ratios of approach flow to saturation flow for the two phases are 0.37 and 0.40. The optimum cycle length using the Webster's method (in seconds, round off to one decimal place) is Enter Your Answer... Checkarrow_forward
- Three-phase a pretimed signalized system for T- intersection, the total lost time per phase is 15 sec. Given that PHF for intersection is 0.91. The table below shows information for all movements included in each phase. (Assume the intersection is isolated, and the traffic flow accounts for the peak 15-min period, and there is no initial queue at the start of the analysis period.) 1 Phase Direction Lane group Number of Lanes Volume (veh/h) 2 Northbound Southbound Northbound LT TH & RT ΤΗ I I 250 1800 390 1800 1 270 1600 2- Determine the average vehicle delay for each traffic lane. 3- Evaluate the level of service (LOS) for each traffic lane. 3 Westbound LT 1 250 2500 Saturation flow (veh/lane/hr) 1- Using the Webster method, determine the optimum cycle length and the effective green time for each phase.arrow_forwardProblem 17.2W You are given the following design hourly volume (pc/h) of an intersection with 4 approaches, all without an exclusive right-turn lane. In the following table, fill in the volumes and use them to determine the 8 NEMA movements. Fill in the movement numbers 1 to 8 in the last row of the table.arrow_forward3. An intersection approach has two lane groups: left-turn lane group, and through/right-turn lane group. The control delay is 37 seconds/vehicle for the left-turn lane group, and 27 seconds/vehicle for the through/right-turn lane group. The analysis flow rate is 97 vehicles/hour for the left-turn lane group, and 450 vehicles/hour for the through/right-turn lane group. Calculate the approach control delay and write the corresponding level of service (LOS) for the approach in the box below.arrow_forward
- Traffic and Highway EngineeringCivil EngineeringISBN:9781305156241Author:Garber, Nicholas J.Publisher:Cengage Learning