Saturation Flow Rates and Maximum Critical Lane Volumes for Planning Applications in Maryland

2005 ◽  
Vol 131 (12) ◽  
pp. 946-952 ◽  
Author(s):  
Jenish Joseph ◽  
Gang-Len Chang
Keyword(s):  
Flow Rates ◽  
Saturation Flow

Trajectory-Based Measurement of Signalized Intersection Capacity

2019 ◽  
Vol 2673 (10) ◽  
pp. 370-380 ◽  
Author(s):  
Walid Fourati ◽  
Bernhard Friedrich
Keyword(s):  
Cycle Time ◽  
Degree Of Saturation ◽  
Limiting Factor ◽  
Signal Timing ◽  
Flow Rates ◽  
Practical Applications ◽  
Road Intersections ◽  
Good Signal ◽  
Saturation Flow ◽  
Over Time

Capacities of road intersections are a limiting factor and crucial for the performance of road networks. Therefore, for purposes of intersection design and of optimal signal timing, numerous methodologies have been proposed to either estimate or directly measure the capacity of single movements at road intersections. However, both model-based estimation and direct measurement suffer from the large effort that is needed to gather the relevant data. Even worse, once the data are collected they only represent a snapshot of the capacity over time. This paper proposes an alternative approach to estimate capacity of signalized road intersections over time using only automatically generated trajectories of probe vehicles. The obtained capacity can be used to evaluate the effective degree of saturation using real demand, or to assess hypothetic different conditions in demand or signaling. The cyclic operation of signalized intersections allows for the accumulation of trajectories, and thus in practical applications for the compensation of potentially low penetration rates. Within a sequential process the intersection’s cycle time and the approach green time and saturation flow rates are determined. The determination of the cycle time and the green times is based on an existing approach. The derivation of the saturation flow rates relies on its direct dependency to the saturation time headway and uses two parameters to be calibrated. Testing with a commercial dataset on an intersection in Munich produced a good signal timing estimation and saturation flow values that are comparable to a calculation based on the German guideline.

Estimating Intersection Approach Delay Using 1985 and 1994 Highway Capacity Manual Procedures

1996 ◽  
Vol 1555 (1) ◽  
pp. 23-32
Author(s):  
Stephen M. Braun ◽  
John N. Ivan
Keyword(s):  
Field Measurements ◽  
Signalized Intersections ◽  
New Technique ◽  
Adjustment Factor ◽  
Highway Capacity ◽  
Flow Rates ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
A New Technique ◽  
Saturation Flow

The current methods for determining average stopped delay at signalized intersections were studied. Field measurements of average stopped delay were obtained and compared with values computed using both the 1985 and 1994 editions of the Highway Capacity Manual (HCM). The 1994 HCM uses an equation to predict the progression adjustment factor (PF), a new technique for determining the left-turn adjustment factor for saturation flow rates, and a new set of equations for determining the uniform delay parameter for left-turn lane groups with primary and secondary phasing. Overall, the 1994 HCM produces better estimates of intersection stopped delay than the 1985 HCM.

Effects of Inadequate Driveway Corner Clearances on Traffic Operations, Safety, and Capacity

1997 ◽  
Vol 1579 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Cheng-Tin Gan ◽  
Gary Long
Keyword(s):  
Conflict Analysis ◽  
Traffic Operations ◽  
Inventory Data ◽  
Flow Rates ◽  
Left Turn ◽  
Turn Signal ◽  
Arterial Streets ◽  
Operational Safety ◽  
Traffic Conflict ◽  
Saturation Flow

Inadequate driveway corner clearances can result in traffic operational, safety, and capacity problems. These problems can be caused by blocked driveway ingress and egress movements, incomplete turning maneuvers, conflicting intersection turning movements, confusing right-turn signal indications, insufficient weaving and merging section lengths, and various other conflicts. The effects of driveway corner clearances on safety cannot be examined easily through safety records given the current condition of the available crash and system inventory data. This provides incentives for applying theoretical traffic conflict analysis. A simple conflict analysis showed an increase in merging and crossing conflict points for driveways situated near intersections. Inadequate corner clearance can have a capacity-reducing effect. Driveway capacity may be reduced by ( a) vehicles on the arterial blocking driveway egress movements and ( b) a decreased opportunity for left-turn egress movement on arterial streets designed for platoon progression. Intersection capacity can also be reduced by a decrease in saturation flow rates due to driveway ingress and egress movements.

scholarly journals Estimation of Saturation Flow Rates at Signalized Intersections

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Chang-qiao Shao ◽  
Xiao-ming Liu
Keyword(s):  
Normal Distribution ◽  
Flow Rate ◽  
Goodness Of Fit ◽  
Estimation Method ◽  
Fundamental Parameter ◽  
Goodness Of Fit Test ◽  
Flow Rates ◽  
Average Value ◽  
Saturation Flow Rate ◽  
Saturation Flow

The saturation flow rate is a fundamental parameter to measure the intersection capacity and time the traffic signals. However, it is revealed that traditional methods which are mainly developed using the average value of observed queue discharge headways to estimate the saturation headway might lead to underestimate saturation flow rate. The goal of this paper is to study the stochastic nature of queue discharge headways and to develop a more accurate estimate method for saturation headway and saturation flow rate. Based on the surveyed data, the characteristics of queue discharge headways and the estimation method of saturated flow rate are studied. It is found that the average value of queue discharge headways is greater than the median value and that the skewness of the headways is positive. Normal distribution tests were conducted before and after a log transformation of the headways. The goodness-of-fit test showed that for some surveyed sites, the queue discharge headways can be fitted by the normal distribution and for other surveyed sites, the headways can be fitted by lognormal distribution. According to the queue discharge headway characteristics, the median value of queue discharge headways is suggested to estimate the saturation headway and a new method of estimation saturation flow rates is developed.

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