Method and apparatus for level of service assessment at signalized intersections

Patent metadata

Field	Value
Publication number	US-11741830-B2
Application number	US-202117411463-A
Country	US
Kind code	B2
Filing date	Aug 25, 2021
Priority date	Aug 25, 2021
Publication date	Aug 29, 2023
Grant date	Aug 29, 2023

Abstract

A method and apparatus for level of service assessment at signalized intersections is disclosed. In an exemplary embodiment, a method for estimating an average delay per vehicle at a signalized intersection with a traffic signal, including sampling vehicle arrival rates at the signalized intersection, sampling vehicle departure rates at the signalized intersection, analyzing generated shock waves at the traffic signal, wherein the traffic signal shock wave is a change in vehicle density due to changes in the traffic signal, and estimating the average delay per vehicle based on the vehicle arrival rates, the vehicle departure rates, and the traffic shock waves at the signalized intersection.

First claim

The invention claimed is:

1. A method for estimating an average delay per vehicle at a signalized intersection having a traffic signal, including:
sampling, by a controller, vehicle arrival rates at the signalized intersection;
sampling, by the controller, vehicle departure rates at the signalized intersection;
analyzing, by the controller, traffic shock waves that occur at the signalized intersection, wherein the traffic shock waves are a change in vehicle density due to changes in the traffic signal; and
estimating, by the controller, the average delay per vehicle based on the vehicle arrival rates, the vehicle departure rates, and the traffic shock waves at the signalized intersection;
wherein the estimating comprises determining the average delay per vehicle in accordance with

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where,
C is traffic signal cycle length,
R is Red light time interval,
ω AB is shock wave speed between flow states, arrival state A and jam state B,
ω BC is the shock wave speed between flow states, jam state B and saturation state C,
Qa is arrival rate of vehicles,
k jam is traffic density at flow state B,
d is safe vehicle deceleration rate,
K a is traffic density of arriving vehicles.

2. The method for estimating the average delay of claim 1 , wherein the analyzing the generated traffic shock waves comprises:
determining, by the controller, a shock wave speed between an arrival flow state and a stopped flow state; and
determining, by the controller, the shock wave speed between a stopped flow state and a departure flow state.

3. The method for estimating the average delay of claim 2 , further comprises:
determining, by the controller, a stop delay of the stopped flow state based on a red traffic signal time interval and a queue length in vehicles.

4. The method for estimating the average delay of claim 1 , wherein the sampling, analyzing and estimating steps are performed by the controller of a single level of service logging device.

5. The method for estimating the average delay of claim 1 , further comprising:
performing, by the controller, a dynamic sampling method in which a sampling error is calculated after each reading, wherein the sampling error is dependent on a number of observations, variance of the observations, and a degree of confidence; and
after reaching a sampling stopping criterion based on the sampling error of the dynamic sampling method, performing, by the controller, the estimating the average delay per vehicle.

6. The method for estimating the average delay of claim 5 , wherein the sampling error is less than an allowable error in arrival and departure headway observations, wherein the allowable error is a function of a human-machine error for a level of service logging device.

7. A level of service data logging device at a signalized intersection having a traffic signal and, comprising:
a microcontroller;
a memory;
a display device;
a start button; and
at least one data entry button,
the microcontroller configured to
receive an input from the start button to start a level of service measurement and open a data storage file in the memory,
receive an input from the at least one data entry button when a first vehicle stops after the traffic signal turns red,
receive an input from the at least one data entry button when a second vehicle arrives and record an arrival headway as a difference between an arrival time of the second vehicle and an arrival time of the first vehicle,
continuously update a mean and a standard deviation of the arrival headway,
calculate a standard error of the arrival headway mean,
continue to receive the input for additional vehicles' arrival headways and update the mean and standard deviation of the arrival headway until a number of vehicles stopped at the signalized intersection reaches a predetermined queue number or the traffic signal turns green,
when the traffic signal turns green the stopped vehicles in the queue start moving, receive an input when the first vehicle discharging from the queue passes the traffic signal,
receive an input when a following vehicle passes the traffic signal and record the discharge headway during the departure as a difference between a passing time of the discharging vehicle and a passing time of a previous discharging vehicle during the departure,
update a mean and a standard deviation of the discharge headway during the departure,
calculate a standard error of the discharge headway mean during the departure,
continue to receive the input for additional vehicles and update the mean and standard deviation of the discharge headway during the departure until a data collection stopping criteria is reached,
when the data collection stopping criteria is reached, determine an average delay per vehicle, and
display the determined average delay per vehicle on the display device;

wherein the microcontroller is further configured to determine the average delay per vehicle in accordance with

Assignees

• Univ Imam Abdulrahman Bin Faisal

Inventors

• Eldessouki Wael Mohamad Elsayed

Classifications

• G08G1/0145 Primary

  for active traffic flow control · CPC title

• G08G1/012

  from other sources than vehicle or roadside beacons, e.g. mobile networks · CPC title

• G08G1/017

  identifying vehicles (G08G1/015, G08G1/054 take precedence) · CPC title

• G08G1/0133

  for classifying traffic situation · CPC title

• G08G1/08 Primary

  according to detected number or speed of vehicles · CPC title