Traffic accident prevention has always been a hot topic of research for scholars worldwide. In my country alone, 667,507 traffic accidents occurred in 2003, resulting in economic losses of up to 336,914 million yuan. Information System for Traffic Safety (IIS) provides an advanced set of methods and scientific approaches for comprehensive control over a wide area, effectively managing traffic, reducing accidents, and improving transportation safety. Given the development of IIS technology in various countries and my country's current situation, this research focuses on early warning systems related to highway safety. It explores the functions and design principles of IIS-based highway safety early warning systems, aiming to establish a comprehensive traffic accident early warning mechanism using electronic monitoring, variable message signs, and modern communication technologies. Addressing the hazards of severe weather such as rain, snow, fog, and sandstorms to traffic safety, as well as the impact of road conditions on traffic operation, this research continuously improves the early warning model for highway traffic management, establishing a rapid response mechanism centered on preventing and reducing traffic accidents, and preventing secondary accidents. This is of great significance for improving road safety management and expanding the application areas of IIS. 1. Current Research Status Early warning targets predictable adverse factors that may affect safe driving on highways, such as traffic congestion, major traffic accidents, dense fog, snow, flood damage, earthquakes, and fires. From a technical perspective, safety early warning involves advanced traffic information service systems and advanced traffic management systems. Its service targets are emergency event management systems, which vary depending on the design of the IIS (Internet Information Services) architecture in different countries. For example, the US emergency event management system is specifically designed for managing emergencies. European IIS systems integrate emergency event management more into advanced traffic management systems and corresponding safety control systems. Japan's emergency situation management is a module within its advanced road traffic system. Based on the reality of frequent earthquakes, it has constructed a multi-faceted support system that monitors satellite data and information transmitted from vehicles, including a geographic information system (GIS) to track the network and disaster situation during disasters, and route guidance for emergency rescue and repair vehicles. According to research and a review of numerous relevant materials, China currently lacks a comprehensive safety early warning system for highways. To improve the current state of highway traffic safety early warning in China and narrow the gap with developed countries in highway development, it is necessary to research and construct a safety early warning system suitable for the actual conditions of China's highways. 2. Influencing Factors There are many factors affecting early warning, and they are complex and intertwined. They are internal and external to the system, as well as natural and man-made. They can be summarized as follows: (1) Natural causes: Natural phenomena such as snow, rain, fog, dust storms, and earthquakes can cause potential traffic hazards, which manifest in two ways: First, they greatly reduce visibility, making it difficult for drivers to see the road ahead and the surrounding conditions; second, the mixture of rain, snow, fog and accumulated oil and mud on the road reduces the adhesion between the tires and the road surface, resulting in tire slippage, extended braking distance, and brake deviation, which will lead to more frequent traffic accidents. (2) Social causes: With the continuous deepening of reforms, there are changes in the system and the redistribution and transfer of rights and interests among different subjects in society, resulting in unstable factors. (3) Management causes: Inaccurate decision-making, loss of management control, and poor command and guidance can lead to regional road traffic congestion and disorder, or the situation can continue to spread due to the failure to control the situation in time. (4) Human factors: People's modern road safety awareness is the premise for the normal operation of the modern road traffic system. Traffic violations or human-caused damage to the road traffic control system may cause traffic accidents, thus becoming the cause of early warning. (5) Road and infrastructure factors: such as infrastructure construction, whether the road design is reasonable, and road maintenance and construction may all cause traffic accidents. 3 Composition of the early warning system The early warning system is a part of IIS. It uses modern communication and information collection technology to provide the emergency rescue system with the ability to identify, notify, and detect emergency events in advance. The basic idea is to use advanced IIS technology to study the problem of timely prediction of safety hazards, and to use the idea of ​​systems engineering to analyze the social resources and information collection methods of early warning. Based on a certain theoretical model, it infers and judges whether there are factors that will cause accidents, releases information to the highway service objects in a timely manner, and activates the emergency rescue system to prevent accidents. The composition of the early warning system is as follows. 3.1 Information collection The information collection method is to establish a road traffic emergency event information collection network that combines points, lines, and surfaces to discover emergency event scenes in a timely manner and accelerate the transmission of information. Since the time it takes for traffic congestion caused by an emergency to dissipate is exponentially related to the response time of the emergency, timely detection of abnormal traffic phenomena is of great significance. The main data collection targets include: 1) Vehicle detection and classification: Computer vision provides a more intuitive and convenient means of analysis for traffic systems, and the traffic environment contains a large amount of information. Computer vision is used to understand and process vehicle types and classify them. 2) Traffic flow detection: Traffic flow detection is an important component of highway monitoring systems. Real-time and reliable basic traffic information is the fundamental basis for judging traffic conditions and a prerequisite for realizing intelligent highway management. 3) Speed ​​detection: The speed of a vehicle directly reflects the road's capacity. Speed ​​can generally be classified as: location speed, operating speed, section speed, critical speed, time-averaged speed, spatial average speed, free speed, median speed, 85th percentile speed, 15th percentile speed, design speed, etc. Different speed concepts are applied in different areas. For example, the critical speed reflects the maximum capacity of a road; vehicles travel at this speed when the road's capacity is strongest. The 85th percentile speed is usually used for the maximum speed limit on a certain road section; the 15th percentile speed is usually used for the minimum speed limit on a certain road section. 4) Vehicle Stop Detection: Vehicles traveling on highways inevitably need to stop urgently due to special circumstances (such as vehicle breakdown). Due to the high speeds on highways, improper handling after an emergency stop can easily cause rear-end collisions. Therefore, it is necessary to monitor the operation of vehicles on the road in a timely manner, and promptly rescue and handle any abnormal stops. 5) Vehicle Speeding Detection: In recent years, while the total number of traffic accident fatalities has shown a slight decrease or fluctuation, the number of deaths caused by speeding accidents has shown a significant and rapid upward trend. Therefore, strengthening the supervision and management of speeding and other illegal traffic behaviors is of great significance for reducing traffic accidents, mitigating accident losses, and saving lives. 6) Road congestion detection: When traffic demand exceeds the maximum capacity of the highway or a traffic accident occurs on the road, traffic congestion is inevitable. Road congestion leads to increased operating costs, higher accident rates, energy waste, air pollution, and many other adverse effects. 7) Weather condition detection: This mainly includes wind speed, wind direction, temperature, visibility, etc. 8) Road, bridge, and tunnel detection: Monitoring of road surface water accumulation, snow accumulation, bridge stress analysis, tunnel traffic parameters, etc. 3.2 Information transmission: Based on the characteristics and nature of emergency event information, the information transmission method is determined. For example, for large amounts of information such as images, existing highway-dedicated optical cables are used for transmission. In locations where optical cables are difficult to access, GSM/GPRS technology is used for communication. 3.3 Information Processing The Traffic Control Center, based on the obtained traffic parameters, weather parameters, road conditions, bridge conditions, and road maintenance status, conducts reasonable analysis to determine the content, location, and dissemination method of early warning information. This is the core of the system and mainly includes: 1) The Early Warning and Accident Confirmation Subsystem: Relying on various signal acquisition devices and road maintenance information, it predicts traffic events. Besides aiding in accident prevention, it also allows for timely detection and confirmation of accidents by rescue personnel when they occur, promptly issuing early warning information to prevent secondary accidents. 2) The Location Processing Subsystem: Upon receiving an alarm, the system immediately begins work, coordinating various functional departments for rescue. Before the emergency response begins, it acquires as much information as possible, automatically locating the accident based on alarm calls, electronic maps, and the GIS system. This provides first-hand data for accurate rescue, such as the exact location of the accident, the number of vehicles and personnel involved, the exact location of nearby hospitals, the nearest fire-fighting facilities, and other available equipment at the scene and during emergency transport. This greatly facilitates successful rescue. 3) The early warning information storage subsystem establishes an early warning information database, which can improve early warning handling measures when similar events occur, provide reasonable references for various emergency events, and serve to improve the level of road traffic management. 3.4 Early Warning Information Release Early warning information release is divided into two parts: direct release and indirect release. Weather information and traffic information are examples of direct release, while information on traffic events determined by traffic parameters and road maintenance information is sent and displayed by the traffic control center, which is an indirect release method. The release format can be variable message signs, voice, etc., depending on the situation. 4 Conclusion China's intelligent transportation system is still in its early stages of development and is proceeding in parallel with the construction of the road network. Road construction will be a major task for China's transportation departments for a considerable period. Therefore, the early warning system under the framework of the intelligent transportation system should be included in the infrastructure construction. Designing a safety early warning system scheme suitable for the actual operation of China's expressways, based on the actual situation of China's expressways, can improve the level of expressway management, provide guarantees for safe driving on expressways, and have significant social benefits.