Signal Cycle Time Research Articles

Use of Probe Vehicle Data to Determine Joint Probability Distributions of Vehicle Location and Speed on an Arterial Road

Monitoring traffic conditions over large road networks is a significant challenge for many transportation authorities. However, the rich data from probe vehicles that have become available in recent years can assist with such traffic monitoring. Hydrodynamic theory and horizontal queuing theory are used to derive the joint probability distribution function of vehicle location and speed on an arterial road for undersaturated and congested traffic conditions. Specifically considered are the effects of signal controllers (including deceleration, acceleration, and queuing) on the distributions of location and speed. This probabilistic model is parameterized by link parameters (red signal time, cycle time, and critical flow density), driving behavior (average deceleration and acceleration, average speed, and variation of arrival flow and dissipating flow), and traffic state (arrival flow density) obtained from historical probe data (for location and speed) with maximum likelihood estimates. In a numerical experiment with data collected from private cars in Toyota City, Japan, for the 2011 Green Project, the Kolmogorov–Smirnov test validates the use of the proposed distributions of vehicle location and speed.

Research on Reasonable Bus Priority Method Based on Arterial Coordination Control

In the previous study, the bus priority control strategies only provide priority for the later bus, while ignoring the adverse effects of the early bus. This paper proposed a reasonable bus priority control strategy taking the arterial coordination control section as research object and aiming to the buses running schedule offset (positive, negative) minimum. Established a double-layer model for reasonable bus priority based on arterial coordination control, the upper layer is arterial coordination control, the lower layer is the bus priority control. In the arterial coordination layer, the detector detects the social vehicle flow data to optimize the communal signal cycle time, green ratio and phase difference; the reasonable bus priority optimization layer, specify the coordination phase green wave band limit as constraint conditions of adjusting the parameters of distribution, and establish the bus priority application model based on timetable, separately control the late and early bus without damaging the coordination phase green-wave.

Simulation of Signalized Intersection Model

Signalized intersection delay is an important evaluation index of the signalized intersection capacity and level of service. This paper presents a signalized intersection delay model for signalized intersection. The model uses time series and queuing theory. It discusses the operation characteristics of the process of arrival and leaving and optimizes the intersection signal timing and gets the best signal cycle time. A scientific model and a more complete analysis are founded in the paper. These methods have a good reference value to the relevant departments.

Research of Signalized Intersection Delay Problem by Time Series and Queuing Theory

Signalized intersection delay is an important evaluation index of the signalized intersection capacity and level of service. This paper presents a signalized intersection delay model for signalized intersection. The model uses time series and queuing theory. It discusses the operation characteristics of the process of arrival and leaving and optimizes the intersection signal timing and gets the best signal cycle time. A scientific model and a more complete analysis are founded in the paper. These methods have a good reference value to the relevant departments.

A Threshold-Based Real-Time Incident Detection System for Urban Traffic Networks

As incident detection on a typical busy urban road link or intersection still demands more efficient algorithms, this paper introduces a methodology that can be used to characterize the various traffic patterns (incident or no incident) using typical link passage detectors. Offline urban incident scenarios are generated using a microscopic simulation model assuming varying traffic link flows, signal green phase and cycle times, link lengths. Similar scenarios are also generated for non-incident cases. Three detectors were assumed on each link to extract traffic measures. Comparative numerical statistical analyses were conducted to identify the traffic measures (such as the average speed and flow) that are likely to be affected by the incidents. And further analysis was conducted to quantify the most probable thresholds to be used in the proposed urban incident detection model. The proposed model is validated using simulation data. The performance of the proposed model is assessed using dynamic performance indicators such as the success rate of detecting an incident at a specific cycle time, and the false alarm rate.

Capacity of Bicycle Platoon Flow at Two-Phase Signalized Intersection: a Case Analysis of Xi’an City

Although much is known about the operation of signalized intersections, little or no empirical research has been conducted regarding bicycle capacity at these locations and the correspondent contributory factors. The purpose of this study is to accurately quantify the capacity of bikeway at signalized intersection through a fluid dispersion approach, and ultimately the lane group capacity. Using this total dispersion of bicycle flow, a relationship is also described between bicycle volume per hour and per unit width, signal parameters (length of signal cycle and green time), bicycle flow (arrival rate, density, moving velocity) and geometric intersection distance. Through the videotaping of four intersections that have significant bicycle traffic around Xiaozhai in Xi’an, China, it is ascertained that bicycle capacity varies linearly (but limited by an asymptote domain) associated with the adjustment of these parameters. The analytical results indicate that the impact saturation flow of lane groups containing right-turning vehicles and pedestrian flow at signalized intersections on bicycles is being underestimated. If this is the case, then capacity is being overestimated through the HCM 2000 capacity model and JJ37-90 approach and intersections are not being adequately designed, due to the neglect of conflict nature of mixed traffic arrivals in competing for space.

Mitigating Traffic Congestion and Accidents in Thailand with Intelligent Transportation System Technology

Geometrical features of intersections, such as T-intersections and four-leg intersections, can give rise to several conflict points at those intersections. Without proper control at such conflict points, accidents can occur. In Thailand, the application of intelligent transportation system (ITS) technology for improvement of traffic flow and road safety is still in its infancy. This paper describes one of the pioneering uses of ITS technology to mitigate congestion and reduce accidents at intersections. The intersections under study are located in suburban Bangkok, Thailand, where major accidents have occurred as a result of red light running and speeding. Through the use of accident analysis modeling and ITS technology, it is possible to improve traffic flow and reduce the number of crashes. ITS technology, including an image-sensing concept for adaptive synchronization (green wave), was used to detect headway, spacing, number of speeding vehicles, angle of lane changing, and number of vehicles changing lanes. In particular, the image-sensing concept of traffic classified counting was used to calculate and evaluate signal phasing and cycle times for adaptive synchronization. In this operation, two closed-circuit television cameras and electronic equipment installed at each intersection were used to track vehicles passing through virtual loops, similar to the way in which induction loops in pavement detect vehicles. A variable message sign was used to flash a warning to errant drivers. After the implementation of this locally developed ITS technology, traffic flow improved significantly and the number of accidents caused by red light running and speeding decreased drastically.

Evaluating the impact of free left turns on traffic behavior at signalized intersections in heterogeneous traffic conditions

Traffic signals optimise efficiency and safety at intersections by separating conflicting traffic movements in time. To achieve the same vehicle throughput in a reduced signal cycle time, often free left turns are provided for left side driving traffic. The current study intends to evaluate the impact of these free left turns on the traffic behavior by i) measuring their existing capacity utilization and ii) establishing the various factors influencing their performance. Queue lengths and travel times of the left turning vehicles are taken as the indicators of their performance. VISSIM software is used for micro-simulation of traffic and from the results obtained, regression models are developed for queue lengths and travel times. Also, effect of a signalized left turn in place of a free left turn is estimated in terms of the alteration it causes on the queue lengths and travel times of left turning vehicles.

Analysis of pedestrian behaviour and risk while crossing road at signalised intersection of Delhi, India: before and after construction of flyover

Pedestrians on Delhi roads are often exposed to large risks. This is because the basic needs of pedestrians are not recognised as part of the urban transport infrastructure improvement projects...

Implementation of Two-step Crossing System with Cycle-time Reduction: The Effects and Future Tasks

In Japan, and also in other Asian countries, intersections with very long signal cycle time have been problematic especially form pedestrian viewpoint. This research aims to suggest a technique to solve the problems: 2-step crossing system with cycle time reduction, as a new standard of intersection design in Japan and other Asian countries as well. To check the effects of it, an experimental attempt are conducted in a real intersection and analyzed through a video survey and an interview survey. As a result, the authors revealed how much the effect differs by pedestrian walking direction and that lots of pedestrians accept this kind of experiment and think about the future extension. For future task, installing sound signals and remaining-time indicators, and applying different cycle time will be necessary to make this technique new Asian standard of intersection designing and controlling.

Influences of overtaking on two-lane traffic with signals

Based on the cellular automata method (CA method), two-lane traffic flow with the consideration of overtaking is investigated. Discrete equations are proposed to describe the traffic dynamics by using the rules of CA model. Influences of signal cycle time ( t s ) and vehicular density ( ρ ) on the mean velocity 〈 v 〉 and mean overtaking times 〈 c 〉 of the traffic flow are discussed. The effects of slow vehicles and road barricades on the traffic flow are also studied. Simulation results shows that the vehicular density and the signal cycle time have significant influences on the traffic flow. The mean velocity of the traffic flow could keep a comparatively large value when ρ ≤ 0.45 . For a certain value of ρ , 〈 v 〉 displays a serrated fluctuation with t s . Therefore, there may exist a certain combination of ρ and t s which optimizes the traffic flow efficiency. As compared with the results in Nagatani (2009) [7], the model proposed here and the simulation results which took into account the effects of signal cycle time, slow vehicles, and road barricades on the traffic flow with overtaking allowed, can reflect the situation of traffic flow in a more realistic way.

A MODIFIED CELLULAR AUTOMATON MODEL FOR RING ROAD TRAFFIC WITH VELOCITY GUIDANCE

We present a modified cellular automaton model to study the traffic flow on a signal controlled ring road with velocity guidance. The velocity guidance is such a strategy that when vehicles approach the traffic light, suggested velocities are provided for avoiding the vehicles' sharp brakes in front of red light. Simulation results show that this strategy may significantly reduce the vehicles' stopping rate and the effect size is dependent upon the traffic density, the detector position, the signal's cycle time and the obedience rate of vehicles to the guidance.

Dynamics and schedule of shuttle bus controlled by traffic signal

We study the dynamical behavior of a shuttle bus moving through a traffic signal. The dynamics of the bus is expressed in terms of the nonlinear maps. The bus dynamics is controlled by varying the loading parameter, the cycle time of signal, and the degree of speedup. We show the dependence of the tour time on both loading parameter and cycle time. The fluctuation of boarding passengers is highly reduced by varying the cycle time. When the bus speeds up to retrieve the delay induced by loading the passengers, the bus behavior also changes highly. The shuttle bus schedule is connected with the complex motion of the shuttle bus. The region map (phase diagram) is shown to control the complex motion of the bus.

Influence of Excitation Frequency and Amplitude on the Switching Properties of SBT and PZT Thin Films at 10 MHZ Hysteresis Frequency

For development and optimization of high density ferroelectric random access memory (FeRAM) devices, it is highly important to understand the polarization switching process. As demands on measurement hardware for these nonlinear devices rise with falling cycle time, the development of faster measurement equipment is desired for observation. We report on the direct investigation of the switching behaviour near device operation frequency of chemical solution deposition (CSD) prepared thin films of perovskite materials such as strontium bismuth tantalate SrBi 2 Ta 2 O 9 (SBT) and lead zirconate titanate Pb(Zr 0.3 ,T 0.7 )O 3 (PZT) with a newly developed measurement setup. In this work, high speed dynamic hysteresis measurements are performed to further explore the dynamic behaviour of polarization switching into the frequency domain. Virtual Ground measurements down to 100 ns cycle time of excitation signal were achieved, providing additional insight into device operation. A rise of Vc with a factor of 0.065 kV/decade between measurements at 10 Hz and 10 MHz of excitation frequency was confirmed.

Development of an Aggregate Fuel Consumption Model for Signalized Intersections

An aggregate model to estimate intersection fuel consumption is developed, and the effects of signal timing on fuel consumption are investigated. A conceptual framework is proposed to identify interrelationships among traffic characteristics, signal control strategies, and roadway geometric conditions. On the basis of the framework, an Analytical Fuel Consumption Model (AFCM) is developed to estimate fuel consumption at signalized intersections. The AFCM, based on considerations of vehicle operating conditions, describes how fuel is consumed on three street segments (inbound approach, intersection itself, and outbound leg) for three signal cycle stages (the effective red time, queue departure time t0, and remaining green time). Numerical experiments are conducted to test the AFCM estimation capability and to investigate the effects of signal timing on fuel consumption. Results of numerical experiments are compared with results from the TEXAS simulation model using two criteria: differences of total fuel consumption and correlation coefficients of elapsed fuel consumption. Results from the TEXAS model are within 10 percent of those from the AFCM, and the elapsed fuel consumption is highly correlated. This indicates that total fuel consumption estimated from the AFCM is very close to the results from the TEXAS model, which suggests that the mathematical representations of the AFCM might be used to replace the simulation-based model. Moreover, the results from these experiments indicate that total fuel consumption with respect to signal cycle time at signalized intersections possesses a convex pattern, and the optimal cycle length for minimization of fuel consumption can be obtained.

ワンボード・マイコンを利用した障害歩行診断のための無拘束長時間歩行モニタ

A microcomputer-based ambulatory monitor has been developed. This monitor utilizes a CMOS one-chip microprocessor (Toshiba Z 84 C 015-10), which has an Intel Z 80-compatible 8 bit CPU, two 8-bit parallel I/Os, four 8-bit counter/timers, and a fullduplex serial I/O. A general purpose min/max detector circuit has been designed to detect minimum and maximum values of a single-channel cyclic analog signal correlated to human gait. The analog signal fed to this circuit is converted to two logical pulses the width of which is proportional to the minimum and maximum values during one gait cycle. A logical signal which represents the gait cycle is also generated. These three logical signals are connected to three signal lines of a parallel port. Clock pulses of 100Hz and 10kHz are also generated and connected to three counters which convert pulse width or pulse cycle of the logical signals into corresponding digital representations of minimum, maximum, and cycle time of the gait-associated analog signal. The digital representations of 8,000 gait cycles can be stored in 32kbyte RAM, and retrieved from serial port via RS232C interface at a request from any host personal computer. The min/max detector circuit is assembled with DIP ICs, and contains a one-chip microcomputer, other peripheral circuits and a 006 P 9[v] battery, in a plastic box measuring 140(W)×80(H)×40(D)[mm]. The weight of the total monitor box is 120g. As one application of this ambulatory monitor, measurement of stride length and walking velocity was attempted. The absolute segmental angle of the thigh of one leg in the sagittal plain was detected by a piezoelectric gyroscope attached to the top of the knee. The angle signal was fed to the min/max detector circuit. Stride length was estimated from the absolute of this segmental angle by utilizing a simple mathematical model of biped locomotion. Walking velocity can be calculated from stride length and cycle time. The accuracy of the stride length and walking velocity was evaluated for 8 normal female, 11 normal male, 3 hemiplegic, and 3 A/K amputee subjects. The result was promising. Possible applications of this ambulatory monitor for assisting clinical decisions on patients with gait disabilities are discussed.

Pedestrian Travel Times and Motor Vehicle Traffic Signals

Traffic signals generally have been installed to maximize the flow of motor vehicle traffic by reducing the average travel delay time. Under free-flow conditions, motor vehicle travel delay is very sensitive to the amount of green phase and the total cycle of the traffic signal. Average pedestrian delay at traffic signals is not taken into account. Some simple examples are used to demonstrate that travel time delay costs to pedestrians caused by existing signalization cycles may often result in increased travel time costs to society. In areas with heavy pedestrian traffic (or during peak pedestrian hours), traffic signals should trade off the costs of motor vehicle delay with pedestrian delay. This may suggest that in some areas, motor vehicle traffic should be banned or severely restricted. Narrower street widths that can allow reduced total signal cycle times can also reduce pedestrian delay.

Pedestrian Travel Times and Motor Vehicle Traffic Signals

Traffic signals generally have been installed to maximize the flow of motor vehicle traffic by reducing the average travel delay time. Under free-flow conditions, motor vehicle travel delay is very sensitive to the amount of green phase and the total cycle of the traffic signal. Average pedestrian delay at traffic signals is not taken into account. Some simple examples are used to demonstrate that travel time delay costs to pedestrians caused by existing signalization cycles may often result in increased travel time costs to society. In areas with heavy pedestrian traffic (or during peak pedestrian hours), traffic signals should trade off the costs of motor vehicle delay with pedestrian delay. This may suggest that in some areas, motor vehicle traffic should be banned or severely restricted. Narrower street widths that can allow reduced total signal cycle times can also reduce pedestrian delay.

Urban traffic control strategy effects on vehicle fuel consumption

This paper considers techniques to predict and record the performance of different classes of vehicle operating in an Urban Traffic Control system. Fixed-time plans were developed using the TRANSYT predictive model and compared with data recorded with an instrumented car and Heavy Goods Vehicle (HGV). Controlled experiments were carried out on a section of unopened highway to establish cruise, delay and speed change components for the survey vehicles. On-street surveys were carried out on the urban road network in Loughborough with signal co-ordination from fixed-time plans optimised initially for delay and then to minimise fuel. Control strategies were operated in collaboration with the Leicestershire County Council's Urban Traffic Control Unit. The main issues considered are: savings achieved with minimum fuel plans for different size vehicles in peak and off-peak traffic conditions; a comparison of the predicted journey times and for the urban road network with those measured link-by-link with the instrumented vehicles; the relative importance of the cruise, delay and speed change components for the HGV compared with the car; the effect of signal cycle time and other components in establishing fixed-time plans for signal co-ordination that minimised consumption.

Optimum split of signal cycle time for road junctions within an urban network

A method for evaluating the split of cycle time of a junction in an urban traffic network is proposed. The technique seeks to reduce the magnitude of the queues left at the end of a cycle using a concept based on the theory of feedback. This concept, referred to as the self-reflective cycle, uses the feedback of the predicted end of cycle queue to the start of the cycle to yield a value of split. Split is subsequently optimized relative to a criterion function based on delay and stops. The method is well suited to on-line control.