Intelligent transportation system and its application in urban road safety

1 Introduction
According to the current traffic situation in China, it is very necessary to develop an intelligent transportation system. The intelligent transportation system has the following functions: increase the mobility of traffic, improve operational efficiency, increase the capacity of the road network, improve facility efficiency, and regulate traffic demand; improve the safety level of traffic and reduce the possibility of accidents; reduce the degree of damage caused by accidents and prevent the expansion of disasters after accidents; reduce congestion: reduce pollution and reduce the impact of automobile transportation on the environment; the construction of an intelligent transportation system will form a new economic growth point. Intelligent transportation system is a research field that involves a wide range of areas and integrates various high-tech technologies. With the development of modern transportation technology and electronics, communications, computers and other technologies, the realization of intelligent transportation system (ITS) has become possible. Here we focus on the intelligent transportation system and its application in road safety.

2 Intelligent Transportation System
2.1 System Composition
ITS consists of four modular subsystems: center, road, vehicle and remote access, which share common communication equipment, as shown in Figure 1.

ITS can be specifically allocated to each physical subsystem under the four subsystems (a total of 19 physical subsystems) according to functional requirements. Each subsystem, user, and environment are integrated into an organic whole based on data and information exchange. Each subsystem is relatively independent but interconnected. Each subsystem is a single entity, and can complete an ITS strategy through organic reorganization. Figure 2 is the ITS subsystem structure diagram.

ITS uses information, data communication transmission, electronic control, computer processing, sensors and other technologies. The ITS information acquisition module obtains traffic, road, weather and other information through sensors 24 hours a day. Hardware equipment includes image sensors, infrared sensors, laser sensors, sound sensors, radio sensors, etc. The ITS information processing module quickly processes large amounts of data obtained from sensors and converts them into useful information. Hardware equipment includes large computers, main computers, workstations, mobile terminals, simulation technology, optimization algorithms, graphics processing technology, in-vehicle MPUs (for engine control, navigation, etc.), and in-vehicle LANs. The ITS information transmission module transmits a large amount of information to vehicles, mobile terminals and fixed equipment. Wireless systems use DSRCPDA and satellite communications, wired technology uses optical transmission technology and ATM networks, and HMI industrial technology uses large-scale display screens, color PDPs, and liquid crystal display devices.

2.2 Basic data collection
Data collection is the premise of system operation. The intelligent dispatching system has the ability to collect basic data of public transportation operation. These basic data include: passenger flow demand at each bus stop, bus speed and stop time, vehicle driving status, vehicle positioning, etc. Data collection is mainly undertaken by on-board equipment. The vehicle driving recorder has a built-in large-capacity memory, which can record the data of the entire vehicle operation process in real time, including: the date and time of vehicle start and stop, speed and mileage detection of the entire vehicle operation process, data of vehicle braking changes, events occurring during vehicle driving and their time and location, safety data within 30 seconds before the accident to the time of the accident, etc. In addition, it can also display the instantaneous speed, current road code, date and time in real time; it is equipped with door opening and closing indicator lights and overspeed indicator lights, and can prompt the door opening alarm and overspeed alarm when combined with the buzzer; it supports IC card for operation management and vehicle driving data collection; it supports wireless data collection, reserves GPS satellite positioning interface, and can realize vehicle tracking and positioning and real-time vehicle dispatch after function expansion, and reserves flow detection interface, etc.
The short-range wireless communicator is a wireless data acquisition device specially designed for driving recorders. It has a long communication distance (50~80 m), high communication reliability (bit error rate <0.2%), and high speed (115 KB/s). When the vehicle arrives at the destination, the intelligent dispatching system can automatically identify the time, road sign number, vehicle number, and driver number of the vehicle entering the station, and use the wireless automatic acquisition software to automatically transmit the data collected in the driving recorder to the intelligent dispatching system at the terminal by wireless.
2.3 Intelligent dispatching system
The intelligent dispatching system has effective data management and analysis capabilities, including operational data management and analytical data management. Its purpose is to ensure scientific and efficient decision-making and analysis of daily operation management plans and dispatch. The data in the driving recorder is collected by wireless data acquisition, and the vehicle operation status and the driver's driving behavior are analyzed and processed using specific algorithms. The computer displays the vehicle location and operation status in a visual way, and provides safety information with intuitive report data and simple and clear graphical analysis methods. At the same time, it can also display abnormal conditions of the driving recorder's auxiliary equipment and driving violation records. Problem vehicles are warned by flashing red lights on the computer display and voice. On-site dispatch management. Dispatchers can easily monitor and dispatch vehicle operations using the intelligent dispatch system. The on-site dispatch management module consists of two parts: the front-end control program and the intelligent dispatch module. The front-end control program is used to display the line operation status and complete the interaction between the system and the dispatcher.
2.4 Information transmission
The intelligent transportation system will record various operating data and driving reports, waybills and other information and feed them back to the bus company through the set transmission method. The decision-making group will query various reports, charts and related analytical data and information materials to understand the operation status of the vehicle and the utilization of related bus resources, make corresponding judgments and plans, and reasonably dispatch buses to make full use of bus resources.

3 Application of ITS in Urban Road Safety
Traffic accidents are the main cause of traffic jams. The main way to reduce traffic jams and vehicle delays is to reduce the impact of various traffic accidents on traffic flow, and the ITS safety management system has this function. The ITS event management system can effectively reduce traffic delays and traffic jams through the rational application of existing technologies and the coordination and organization of relevant units.
Effective event management can produce huge economic benefits. In order for the system to achieve this goal, the event management system should have the following functions: improve road safety (such as reducing secondary accidents); improve the operating efficiency of various executive agencies; more effectively utilize existing human and material resources; increase the scope and channels of information release; reduce delays; improve the mobility of trucks and vehicles; reduce accident response time; reduce the impact on the environment; reduce operating costs; speed up the time to handle accidents; speed up the time to clear roads.
3.1 Traffic Abnormal Event Detection System Old
3.1.1 System Composition and Principle
The traffic abnormal event detection system consists of traffic condition detection, data processing detection, signal control and information display. When magnetic or ultrasonic detectors are used, the system consists of detectors, data processing detection, accident judgment, accident confirmation, signal control machine, signal lights, variable traffic information display screens, etc.; when video camera detection facilities are used, the system consists of digital cameras, control consoles, image processing devices, information control machines, signal lights, variable traffic information display screens, etc. The basic principle of traffic abnormality event detection: The detector detects the traffic flow of vehicles under normal conditions, and the measured traffic flow parameters should conform to certain rules. Once the detected traffic flow parameters do not conform to the rules, it means that a traffic abnormality event may have occurred. Due to the different road conditions on which vehicles travel, the detection and judgment of traffic abnormalities on highways or long-distance highways are very different from those on urban roads.
3.1.2 Traffic abnormality event detection method
The running state of vehicles on urban roads is different from that on highways. Due to the influence of intersections, they belong to intermittent traffic flow and there will be normal parking on the road. Therefore, when conducting detection on urban roads, it is necessary to first identify whether it is normal parking or abnormal parking, and then conduct detection according to the above principle, so as to correctly judge whether a traffic abnormality event has occurred, so its detection difficulty is higher than that on highways. In addition to detecting traffic anomalies on urban roads, it is also necessary to identify the location where the anomaly occurred.
Method 1: Use various data such as detector detection data, detection car observation data, passing driver and patrol report data, etc. to establish corresponding traffic anomaly detection algorithms for data from various sources, and use data fusion technology to obtain the final detection results of the results of various detection algorithms to detect traffic anomalies.
Method 2: Establish a database of historical data to store the traffic data of the detector in each signal cycle under normal traffic conditions, and use the deviation value between the real-time data of the current detector and the historical data at the same time as the basis for distinguishing abnormal events.
For the determination of the location of traffic anomaly events. When using detectors to detect traffic anomalies, the main solution is to rely on the layout of the detector setting position. As shown in Figure 3, ①② detectors are used to detect abnormal events occurring on the road section, ②③ detectors are used to detect abnormal events occurring on the entrance road, and ③④⑤ detectors are used to detect abnormal events occurring in the middle of the intersection.
3.1.3 System performance and its improvement
The performance of the traffic anomaly detection system is generally evaluated by three indicators: detection rate, false detection rate and average detection time. In order to improve the performance of the detection system, multiple accident tree analysis methods can be used to detect abnormal traffic events on highways; judgment analysis methods and traffic simulation technology can be used to detect abnormal traffic events on urban roads. With the continuous emergence of high-tech achievements, video camera and image processing technology have been continuously improved, and this technology will soon be applied to the detection of abnormal traffic events. The technicians of the video camera monitoring center can directly see the actual traffic conditions on the video monitor screen.
When an abnormal traffic event is found, the traffic management measures for the abnormal event can be released to various information display facilities on the road through manual operation. The roads where detectors are used to detect abnormal traffic events are equipped with digital video monitors, which can be used as a confirmation tool for detecting the type and nature of abnormal traffic events. If computer online automatic operation is used instead of manual operation, image processing technology is required to judge abnormal events. The road traffic conditions captured by the digital camera are transmitted to the emergency detection device, and the detection device then transmits the detection image to the control center through the information transmission line.
The control center collects the image by the image collection device, and after the image is processed into control instruction information by the processing device, the control instruction information is transmitted by the information transmission system to the special information board located on the gantry upstream of the emergency site to display the control instruction information.
3.2 On-site management
The main tasks of traffic standardization on-site management are to accurately assess the severity of the incident, determine the appropriate priority, and coordinate the use of relevant resources. Ensuring clear and unimpeded communications, cleaning up the incident scene safely, quickly, and efficiently through effective measures, and ensuring the safety of incident handling personnel, parties involved in the incident, and other vehicle drivers and passengers are the primary purposes of incident on-site management.
An efficient incident on-site management plan must include: determining an incident on-site command point: appointing an authoritative on-site commander; mobilizing all personnel related to incident handling; and calling emergency vehicles and equipment in stages.

4 Conclusion
Intelligent transportation system is a wide-ranging research field that integrates various high-tech technologies. From the perspective of roads, some measures to improve urban road safety are discussed. Only when various industries develop in a coordinated manner can the improvement of urban transportation levels be jointly promoted.