Saturation Flow Rate, Start-Up Lost Time, and Capacity for Bicycles at Signalized Intersections

2003 ◽  
Vol 1852 (1) ◽  
pp. 105-113 ◽  
Author(s):  
Winai Raksuntorn ◽  
Sarosh I. Khan
Keyword(s):  
Flow Rate ◽  
Field Studies ◽  
Signalized Intersections ◽  
Highway Capacity Manual ◽  
Start Up ◽  
Lost Time ◽  
Saturation Flow Rate ◽  
Saturation Flow ◽  
Bicycle Lane ◽  
Stop Line

A review of the literature shows that capacity and saturation flow rate for on-street bicycle lanes at intersections have not been measured on the basis of bicycle discharge at intersections at the start of the green phase. The Highway Capacity Manual 2000 recommends a saturation flow rate of 2,000 bicycles per hour for a bicycle lane at a signalized intersection. However, this recommendation is not based on field studies at the intersection and is not a function of the width of the bicycle lane. A revised estimate is provided of saturation flow rate, and an estimate is provided of start-up lost time for bicycles based on data collected at the stop line of signalized intersections. In addition, the lateral stopped distance of automobiles from bicycle lanes, the lateral stopped distance of bicycles from adjacent lanes, and the lateral and longitudinal stopped distance between pairs of bicycles at a signalized intersections are presented. Bicycles may form more than one queue within a bicycle lane at the stop line. Since bicycles maintain a certain distance from the adjacent lane and the curb, the number of queues formed varies based on the width of the bicycle lane. Therefore, the saturation flow rate for a bicycle lane depends on the number of queues or the width of the bicycle lane. The saturation flow rates for bicycle lanes of varying widths are proposed on the basis of the lateral stopped distance of bicycles. Empirical evidence from intersections in Colorado and California is used to propose a new method to estimate the capacity for a bicycle lane.

Investigation of saturation flow rate using video camera at signalized intersections in Jordan

2020 ◽  
Vol 11 (1) ◽  
pp. 216-226
Author(s):  
Bara’ W. Al-Mistarehi ◽  
Ahmad H. Alomari ◽  
Mohamad S. Al Zoubi
Keyword(s):  
Flow Rate ◽  
Standard Procedure ◽  
Video Camera ◽  
Signalized Intersections ◽  
Speed Limit ◽  
Local Conditions ◽  
Highway Capacity Manual ◽  
Saturation Flow Rate ◽  
Turning Radius ◽  
Saturation Flow

AbstractThis study aimed to investigate a potential list of variables that may have an impact on the saturation flow rate (SFR) associated with different turning movements at signalized intersections in Jordan. Direct visits to locations were conducted, and a video camera was used. Highway capacity manual standard procedure was followed to collect the necessary traffic data. Multiple linear regression was performed to classify the factors that impact the SFR and to find the optimal model to foretell the SFR. Results showed that turning radius, presence of camera enforcement, and the speed limit are the significant factors that influence SFR for shared left- and U-turning movements (LUTM) with R2 = 76.9%. Furthermore, the presence of camera enforcement, number of lanes, speed limit, city, traffic volume, and area type are the factors that impact SFR for through movements only (THMO) with R2 = 69.6%. Also, it was found that the SFR for LUTM is 1611 vehicles per hour per lane (VPHPL),which is less than the SFR for THMO that equals to 1840 VPHPL. Calibration and validation of SFR based on local conditions can improve the efficiency of infrastructure operation and planning activities because vehicles’ characteristics and drivers’ behavior change over time.

scholarly journals Traffic Characteristics of Protected/Permitted Left-Turn Signal Displays

2000 ◽  
Vol 1708 (1) ◽  
pp. 28-39 ◽  
Author(s):  
David A. Noyce ◽  
Daniel B. Fambro ◽  
Kent C. Kacir
Keyword(s):  
Response Time ◽  
Flow Rate ◽  
Left Turn ◽  
Start Up ◽  
Green Ball ◽  
Lost Time ◽  
Saturation Flow Rate ◽  
Driver Understanding ◽  
Saturation Flow

At least four variations of the permitted indication in protected/permitted left-turn (PPLT) control have been developed in an attempt to improve the level of driver understanding and safety. These variations replace the green ball permitted indication with a flashing red ball, a flashing yellow ball, a flashing red arrow, or a flashing yellow arrow indication. In addition, the Manual on Uniform Traffic Control Devices allows several PPLT signal display arrangements. The variability in indication and arrangement has led to a myriad of PPLT displays throughout the United States. The level of driver understanding related to each PPLT display type, and the associated impact on traffic operations and safety, has not been quantified. A study was conducted to evaluate the operational characteristics associated with different PPLT signal displays. Specifically, the study quantified saturation flow rate, start-up lost time, response time, and follow-up headway associated with selected PPLT displays. No differences in saturation flow rate and start-up lost time were found due to the type of PPLT signal display. Saturation flow rates ranged from 1,770 to 2,400 vehicles per hour of green per lane and were related to differences in driver behavior between geographic locations. The variation in start-up lost time and response time between locations was primarily related to differences in phase sequence. The flashing red permitted indications were associated with the longest follow-up headway times, since drivers are required to stop before turning left with a flashing red permitted indication. The shortest follow-up headway was associated with the five-section cluster display using a green ball indication.

scholarly journals Effect of U-Turns and Heavy Vehicles on the Saturation Flow Rates of Left-Turn Lanes at Signalized Intersections

2020 ◽  
Vol 12 (11) ◽  
pp. 4485
Author(s):  
Abdelrahman Abuhijleh ◽  
Charitha Dias ◽  
Wael Alhajyaseen ◽  
Deepti Muley
Keyword(s):  
Flow Rate ◽  
Signalized Intersections ◽  
The State ◽  
Heavy Vehicles ◽  
Flow Rates ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
Adjustment Factors ◽  
Saturation Flow Rate ◽  
Saturation Flow

The Saturation Flow Rate (SFR) is a primary measure that can be used when estimating intersection capacity. Further, the efficiency of signal control parameters also depends on the accuracy of assumed SFR values. Driver behavior, type of movement, vehicle type, intersection layout, and other factors may have a significant impact on the saturation flow rate. Thus, it is expected that driving environments that have heterogeneous driver populations with different driving habits and cultures may have different SFRs. In practice, the proposed SFRs based on US standards (Highway Capacity Manual, 2016) have been adopted in the State of Qatar without validation or calibration to consider the local road environment and the characteristics of the driving population. This study aims to empirically analyze the saturation flow rates for exclusive left-turn lanes and shared left- and U-turn lanes at two signalized intersections in Doha city, while considering the effects of heavy vehicles and U-turn maneuvers. Empirical observations revealed that the average base SFR, i.e., when the influences from heavy vehicles and U-turns were excluded, could vary approximately from 1800 vehicles per hour per lane (vphpl) to 2100 vphpl for exclusive left-turning lanes and approximately from 1800 vphpl to 1900 vphpl for shared left- and U-turning lanes. Furthermore, this study proposed different adjustment factors for heavy vehicle and U-turn percentages which can be applied in practice in designing signalized intersections, particularly in the State of Qatar.

scholarly journals Estimation of Saturation Flow Rate and Start-Up Lost Time for Signal Timing Based on Headway Distribution

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Yi Zhao ◽  
Wenbo Zhang ◽  
Jian Lu ◽  
Wenjun Zhang ◽  
Yongfeng Ma
Keyword(s):  
Flow Rate ◽  
Queue Length ◽  
Signal Timing ◽  
Start Up ◽  
Adjustment Factors ◽  
Headway Distribution ◽  
Lost Time ◽  
Saturation Flow Rate ◽  
New Perspective ◽  
Saturation Flow

This study aimed to calibrate saturation flow rate (SFR) and start-up lost time (SLT) when developing signal timing. In current commonly used methods, SFR for one given lane is usually calibrated from many subjective adjustment factors and a fixed result. SLT is calculated based on the fixed SFR, which prevents local applications in China. Considering the importance of traffic behavior (headway) in determining SFR and SLT, this study started from headway distribution and attempted to specify the relationships between headway and vehicle position directly. A common intersection in Nanjing, China, was selected to implement field study and data from 920 queues was collected. Headway distribution was explored and the 78th percentile of headway at each position was selected to build model. Based on the developed relationships, SFR and SLT were calibrated. The results showed that SFR and SLT were correlated with queue length. Moreover, the results showed that it was difficult to reach saturated state even with a long queue length. This paper provides a new perspective on calibrating important parameters in signal timing, which will be useful for traffic agencies to complete signal timing by making the process simpler.

Phase Capacity Characteristics for Signalized Interchange and Intersection Approaches

1998 ◽  
Vol 1646 (1) ◽  
pp. 96-105 ◽  
Author(s):  
James A. Bonneson ◽  
Carroll J. Messer
Keyword(s):  
Flow Rate ◽  
Urban Areas ◽  
High Volume ◽  
Traffic Volume ◽  
Passenger Car ◽  
Start Up ◽  
Lost Time ◽  
Saturation Flow Rate ◽  
Saturation Flow

Described in this paper are the development, calibration, and application of models that collectively can be used to predict the saturation flow rate and start-up lost time of through movements at signalized interchange ramp terminals and other closely spaced intersections. These models were calibrated with data collected at 12 interchanges. It is concluded that saturation flow rate decreases as the distance to the downstream queue decreases. This queue is formed by the signal at a downstream intersection. Saturation flow rate increases with traffic pressure, as quantified by traffic volume per cycle per lane. It is recommended that an ideal saturation flow rate of 2,000 passenger-car units per hour of green per lane be used for signalized ramp terminals and other high-volume intersections in urban areas. The data collected for this research indicate that start-up lost time increases with saturation flow rate.

Saturation Flow and Capacity of Shared Lanes: Comparative Evaluation of Estimation Methods

1996 ◽  
Vol 1555 (1) ◽  
pp. 50-58
Author(s):  
G. A. Glannopoulos ◽  
Muhammad A. S. Mustafa
Keyword(s):  
Flow Rate ◽  
Comparative Evaluation ◽  
Field Measurements ◽  
Estimation Methods ◽  
Highway Capacity ◽  
Operational Conditions ◽  
Highway Capacity Manual ◽  
Traffic Volumes ◽  
Saturation Flow Rate ◽  
Saturation Flow

The operation of shared lanes, especially in the case of permitted phasing control, is still considered a complicated task and one for which many procedures and methods have been introduced. Dealt with here is the complexity when left- or right-turn movements or both are made during the unsaturated part of the opposing traffic flow. Three main methods used for estimating the shared lane's saturation flow rate and capacity values—that used in the 1985 Highway Capacity Manual (HCM) and the Australian Road Research Board (ARRB) and the Canadian methods—were analyzed and evaluated. The methodology for the comparative evaluation was based on two main approaches. In the first approach, example 1 of Chapter 9 of the HCM was used as a case study in which left through and left through right shared lanes exist in permitted phase control. In this case several computer runs were performed using the programs SIDRA and SINTRAL to estimate saturation flow and capacity values of the shared lanes opposed by different traffic volumes of the conflicting movements. Results of this approach showed that the 1985 HCM and ARRB methods are fairly close in estimating saturation flow and capacity, whereas the Canadian method gave considerably different results. Analysis showed that the sensitivity of the Canadian method to estimate saturation flow rates of the shared lane in cases of different levels of opposing traffic was an average of 10 times higher than the average of the two other methods, which were very close in their estimation of levels of opposing traffic volumes. In the second approach, field measurements of saturation flow rate values of shared lanes at different locations and operational conditions were compared with the values estimated by the three methods under the same conditions. Results, based on field observations, revealed that the Canadian method estimates of saturation flow were always lower than the measured values. At low saturation flow values, HCM estimates were slightly higher than the observed values; however, at higher saturation flow rate values. HCM estimates closely matched the observed ones. The ARRB method estimates were quite close to the observed saturation flow values under all of the different conditions considered in the field observation task.

Variations in Capacity at Signalized Intersections with Different Area Types

2000 ◽  
Vol 1710 (1) ◽  
pp. 199-204 ◽  
Author(s):  
Xuewen Le ◽  
Jian Lu ◽  
Edward A. Mierzejewski ◽  
Yanhu Zhou
Keyword(s):  
Signalized Intersections ◽  
Capacity Analysis ◽  
Adjustment Factor ◽  
Highway Capacity ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
Central Florida ◽  
Start Up ◽  
Study Results ◽  
Lost Time

The capacity analysis procedure for signalized intersections included in the Highway Capacity Manual (HCM) needs to consider the area type of a given intersection. The area-type adjustment factor used in the procedure is based on conclusions from a limited number of studies. In addition, the procedure for using an area-type adjustment factor is not well defined in the HCM. A study undertaken in central Florida to study the effects of four different area types on the capacity of signalized intersections is summarized. These four area types include recreational, business, residential, and shopping. Study results indicated that differences in saturation headways among different area types were significant. The saturation headways observed in recreational areas were significantly higher than those in other areas for both left-turn and through movements. The through-movement saturation headways obtained in residential, shopping, and business areas were not significantly different. This study resulted in a new area-type adjustment factor of 0.92 for recreational areas, whereas the factor is 1.00 for other areas. Results in this study also indicated that the differences in start-up lost time among different area types were not significantly different. In addition, according to the results of the analysis, 75 percent of the yellow interval in undersaturated conditions and 35 percent of the yellow interval in oversaturated conditions were found to be unused and considered clearance lost time.

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