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Microprocessor Based Control of Traffic Lights

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Abstract:

Due to suitable control measures & strategies which can be countered traffic congestion in urban road & freeway networks leads to degrades the network infrastructure & accordingly reduced throughput. Due to traffic congestion defining the main reasons for infrastructure deterioration is defined, overview of implemented & proposed control strategies is provided for these areas: urban road networks, freeway networks, & route guidance. The impact of various control actions & strategies are illustrated briefly & Selected application results, obtained from either simulation studies or field implementations. Microprocessor based control of traffic light are programmed for automatically run and change their alternatively light automatically. The microprocessor connected to different electronics devices i.e. traffic light controller, a video camera, an electronic display board, compression circuit an I/O interface, a traffic flow detector & connected to the central traffic control computer through the DSL. DSL stands for Digital Subscriber Loop. A traffic light control & information transmission device both are compromised by a microprocessor on the cross road. DLS is used for send the information about the public or news of the central traffic control computer. The control signals, traffic, public information or can go through the DLS to the microprocessor. The microprocessor can control the traffic light & display all the information on the electronic display board. An electronic display board is used for displaying the information that was send by DSP. The traffic flow data of the cross roads can be accessed by the traffic flow detector & the video camera & transmitted back to the central traffic control computer.

Introduction

Old system works on trigger mechanism. But today many traffic light systems operate on the timing mechanism. Timing mechanism changes the light after a fixed intervals of time. In an intersection of roads the invention that is mainly used to control traffic lights relates to an intelligent traffic light control system. Traffic signal systems will need to address many issues in the next millennium, spanning a broad range of technical, social, & political boundaries. The presence or absence of vehicles within certain range is sensed by the system developed by setting the appropriate duration for the traffic signals to react accordingly. An intelligent traffic light system senses the presence or absence of vehicles & reacts accordingly due to that conditions. A manual input device, an enforced switching device & an intelligent detecting device the invention relates to an intelligent traffic light control system comprising a microprocessor, these three devices are responsible wherein the microprocessor is used for controlling traffic lights. The idea behind intelligent traffic systems is that drivers will not spend unnecessary time waiting for the traffic lights to change. The system to achieve a periodic switching the status of on/off of a traffic light is controlled through a microprocessor. An intelligent traffic system detects traffic in many different way. Trigger mechanism is responsible for older system that means older system are works on this mechanism. for inputting control parameters of traffic light to the microprocessor the manual input device is used, for carrying a preferentially direct operation the enforced switching device is use. The enforced switching device are also used for the direct control of traffic light. Current traffic systems react to motion to trigger the light changes. Once the infrared object detector picks up the presence of a car, a switch causes the lights to change. We need to understate & the function of traffic signals so that we can improve driving habits by controlling the speed in order to reduce the number of associated traffic accidents. To reduce the waiting time of each lane of the cars & also to maximize the total number of cars that can cross an intersection the Intelligent Traffic Signal Simulator is designed and developed. The control parameters cannot be automatically adjusted by the system according to traffic flows in each direction this is the shortcoming of prior technique. The more number of drivers who know about the operation of traffic signals, the less frustrated they are going to be while waiting for the lights to change. They have less frustration while waiting for traffic lights It means that the traffic control in an intersection of roads will be not in a best state at all times.

The Traffic Signal System Consists Of Three Important Parts.

The first part is the controller or we can say that the brain of the traffic system. The selection & timing of traffic movements in accordance to the varying demands of traffic signal that controls by a computer controls as registered to the controller unit by sensors.

The second part is the signal visualization or in another words it is signal face. Controlling traffic in a single direction & consist of one or more signal sections are provided by Signal faces which are part of a signal head. These usually comprise of solid red, yellow, & green lights.

The third part is the detector or sensor. Presence of vehicles is indicated by the sensor or detector. One of the technologies, which are used today, in the pavement at intersections wire loops are placed. Electrical inductance caused by a vehicle passing over or standing over the wire loop is change therefore they are activated

Their Demand

With the increase in urbanization & to operate our roadway systems with maximum efficiency traffic congestion comes a greater demand. New technology, such as traffic-responsive closed loop systems or adaptive traffic signal systems using advanced surveillance & traffic management centers, will become increasingly critical for city, county, & state, organizations to meet transportation needs.

Emergence Of Microprocessor-Based Traffic Signal Control

In early 1960s computers were introduced to traffic signal systems. The first computerized traffic signal control system was installed in Canada in 1963. Hardware & software standardization efforts were first initiated In 1970s, when microprocessors are common

, the developments progressed at a relatively modest pace. The philosophy that controllers would provide a basic set of features & standard connectors the National Electrical Manufacturers Association (NEMA) TS1 standard was based . The concept of the new platform was that traffic signal controllers should not be based on static technology (like the Model170 specification) but on widely used commercial standards, allowing new technology to be adopted rapidly

Technical Challenges

Traffic signal research has been conducted in two distinct areas: roadside equipment & analytical-type operations research. The research on roadside equipment has performed by the Government agencies & vendors virtually. Similarly, the research in analytical-type operations are performed virtually. The roadside equipment & analytical models although significant advancements have been made, neither area has been particularly closely coordinated with the other. Many of the following research issues fall outside the typical DOT, commercial, & university organizational structure, but they show considerable promise for improving the operation of traffic signal systems.

System Integration Research

Due to past research, government agencies & vendors in considered isolation have perfected systems that do an excellent job of meeting today's needs, but do not provide the building blocks for cost-effectively implementing integrated & systems manufactured by a variety of vendors. It means that the system manufactured by the vendors do not get the basic building block from the government. Similarly, because many of the assumptions made by the universities developing the models do not reflect the technical limitations or traffic engineering conventions imposed by modern controllers many of the promising control algorithms proposed over the years have never been implemented.

Advanced Transportation Controller

Adaptive controller adjust time or re-time every 30 sec. A computer is used to control an operation by monitoring readings from sensors & sending control signals when necessary. The concept of an ATC was initiated in 1989. Caltrans prepared a report documenting some of the deficiencies of the Model 170 controller & recommended a 3U VME-based platform using OS-9 (12). The concept of the new platform was that traffic signal controllers should not be based on static technology (like the Model170 specification) but on widely used commercial standards, allowing new technology to be adopted rapidly. The initial specification developed by Caltrans was called the Model 2070. Ideally, new technology would be incorporated into the Model 2070 traffic signal controller at a rate similar to that observed in the desktop computing market. As interest in the standard development effort broadened, & more public agencies began participating, an ATC standard emerged that is even less dependent on the processor & operating system than the Model 2070. Process control means automatic control of an industrial process…

  • Characteristics of process control -
  • sensors are main part of the traffic light based on the microprocessor .It is a real-time operation - input from sensors is processed
  • It is an example of the use of feedback - if it is out of balance the sensor input is used to adjust the process & control signals are sent back almost immediately.
  • the timing of each part of the process and the computer usually controls the supply of materials
  • Some more sophisticated systems allow for 'learning' to take place. The computer 'remembers' how the best results were obtained & attempts to reproduce those results

Sensors

Sensors are the main part of any traffic signal system, yet are viewed by many as the weakest link in developing better traffic control systems. Sensing needs include so many detection train detection, nonferrous bicycle detection, emergency vehicle detection, transit vehicle detection, pedestrian detection, vehicle detection and queue estimation. Reliability must increase & costs decrease to facilitate widespread use not only must new sensing technology be developed. Furthermore, standards need to emerge for integrating these sensors into traffic signal systems. The standard practice for bringing any sensor information into a traffic signal controller is via discrete logic (contact open/contact closed), which is limiting & needs to improve.

Summary Of The Invention

In order to overcome above shortcomings of the prior technique, the invention provides an intelligent traffic light control system. The control system can automatically adjust the traffic light control parameters according to the changes of traffic flow in different directions, thereby increasing the traffic efficiency of intersection of roads & achieving a best control for traffic.

The technical solution of the invention is that: an intelligent traffic light control system comprises a microprocessor, a manual input device, an enforced switching device & an intelligent detecting device, wherein the microprocessor is used for controlling traffic lights, the manual input device is used for inputting control parameters of traffic light to the microprocessor, the enforced switching device is used for carrying out a preferentially direct operation, the intelligent detecting device includes one or more panoramic cameras & an intelligent controller, wherein the one or more panoramic cameras are used for capturing real-time traffic flow images of each direction, the intelligent is used for receiving the real-time traffic flow images of each direction through a video capture board, identifying vehicles on each lane of each road, identifying status of driving & stopping of each vehicle, counting the length of queue of vehicles in each lane from the status of driving & stopping of each vehicle & sending an instruction for modifying traffic light control parameters to the microprocessor according to a preset program. The microprocessor modifies the traffic light control parameters after receiving the instruction. Provided with an intelligent detecting device, this system can estimate the jamming condition of each road according to the length of queue of driving or stopping vehicles on each road, make a best control mode using a preset program by adjusting switching order & switching time of traffic lights to adapt to the actual traffic condition, thereby increasing traffic efficiency of an intersection of roads, reducing traffic jam of each road in each direction. That is beneficial to the normal traffic on roads, in particular to morning peak & evening peak of traffic, as the main flow directions of the mass & vehicles in morning peak & evening peak are different. Provided with one or more panoramic cameras, the intelligent detecting device can effectively capture images of traffic jam condition in each direction, thereby simplifying the device & ensuring the control effect at the same time. It is therefore a primary object of the invention to provide a traffic light control & information transmission device that applies the existing broadb& network to transmit data between the central traffic control computer & the microprocessors of the cross roads to avoid the installation of the cables & save the construction cost.

In order to achieve the objective set forth, a traffic light control & information transmission device in accordance with the present invention comprises a microprocessor on the cross road, the microprocessor further connects to a traffic light controller, an electronic display board, a video camera, a compression circuitry, an I/O interface, a traffic flow detector & connected to the central traffic control computer through the DSL (Digital Subscriber Loop). The control signals, traffic, public information or news of the central traffic control computer can go through the DSL to the microprocessor; the microprocessor can control the traffic light & display all the information on the electronic display board. The traffic flow data of the cross roads can be accessed by the traffic flow detector & the video camera & transmitted back to the central traffic control computer.

Application Of Traffic Models

Many modeling procedures & techniques have been tried over the years & have achieved varying levels of acceptance & use. These models can be classified as macroscopic or microscopic. Macroscopic models are based on average flow rates & average signal timings. They are particularly useful for signal system timing design software because they provide efficient procedures for formulating objective functions used in optimization logic. In the past decade, many of the macroscopic models have incorporated more detail to account for actuated signals & coordination between them. However, these macroscopic models only provide analytical estimates of average system performance & do not provide insight into the actual signal system operation, particularly during non steady-state conditions such as emergency preemption or timing plan transitions. Microscopic models are based on car-following theory & cycle-by-cycle signal times. These models have significant potential to evaluate & visualize alternative control concepts for traffic signal systems because they consider the car-following dynamics of traffic streams & they can model many of the characteristics of advanced systems such as coordinated actuated controllers. These microscopic simulation procedures can be used to analyze & tune coordinated-actuated systems directly, because they consider a majority of the parameters used in modern, coordinated-actuate signal systems. However, microscopic models.

Traffic Control Concepts

Traffic control concepts for isolated intersections basically fall into two basic categories:

1. Pre-Timed Signal Control

Under these conditions, the signal assigns right-of-way at an intersection according to a predetermined schedule. The sequence of right-of-way (phases), & the length of the time interval for each signal indication in the cycle is fixed, based on historic traffic patterns. No recognition is given to the current traffic demand on the intersection approaches unless detectors are used. The major elements of pre-timed control are fixed cycle length, fixed phase length, & number & sequence of phases

2. Traffic-Actuated Signal Control

Traffic-actuated control of isolated intersections attempts to adjust green time continuously, &, in some cases, the sequence of phasing. These adjustments occur in accordance with real-time measures of traffic demand obtained from vehicle detectors placed on one or more of the approaches to the intersection. The full range of actuated control capabilities depends on the type of equipment employed & the operational requirements.

Conclusion

An intelligent traffic light system had successfully been designed & developed. Increasing the number of sensors to detect the presence of vehicles can further enhance the design of the traffic light system. Another room of improvement is to have the infrared sensors replaced with an imaging system/camera system so that it has a wide range of detection capabilities, which can be enhanced & ventured into a perfect traffic system.

 


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