Traffic congestion is a persistent problem in major cities worldwide. In the United States, for example, between 1980 and 2003, the number of vehicles increased by 77% annually, while the mileage of newly constructed roads only increased by 2% during the same period. During peak traffic hours, 54% of public buses are overcrowded. Due to traffic congestion, people spend an average of 1.5 hours more commuting each day than usual. This also leads to delays for commercial vehicles, increasing transportation costs. Limited land and economic resources prevent road construction from reaching a satisfactory mileage. To improve the capacity of the existing road network without expanding its size, it is necessary to comprehensively utilize advanced technologies to improve transportation efficiency. Solution Selection Intelligent Transportation Systems (ITS) effectively integrate advanced information technology, data communication and transmission technology, electronic control technology, sensor technology, and computer processing technology into the entire transportation system, thereby establishing a real-time, accurate, and efficient comprehensive transportation management system that operates across a wide range and in all aspects. This system mainly includes a traffic management system, a travel demand management system, a public transportation operation system, a vehicle operation system, an electronic toll collection system, an emergency management system, and a vehicle monitoring and safety system. It is an integrated application of high technology and advanced communication methods in the transportation system. The vehicle monitoring system is an important component of ITS. Almost all vehicle monitoring systems rely on GPS and GIS electronic map technology. The electronic map database under GIS conditions provides a visual carrier for storing and managing monitoring information for the vehicle monitoring system. GPS positioning technology makes real-time tracking in vehicle monitoring possible. Communication technology builds a data communication bridge between GIS and GPS, making remote monitoring possible. Through accurate positioning, combined with communication technology and electronic maps, the vehicle monitoring system can perform real-time route monitoring, thereby guiding vehicles to avoid congested sections, improving road capacity, and alleviating traffic congestion. This article introduces a GPS-based real-time display and positioning system for buses. [b]System Feasibility Analysis[/b] In the 1990s, in order to effectively alleviate the pressure on transportation, my country introduced the concept of intelligent transportation and actively took measures to accelerate the application of intelligent transportation technology. Currently, research on core ITS technologies in China mainly focuses on image recognition technology, traffic simulation technology, GPS/GIS positioning and navigation technology, and traffic flow theory. GPS applications are primarily in vehicle positioning and navigation, while GPS vehicle monitoring systems are emerging, especially in special vehicles and taxis. For example, Beijing successfully completed the research on the introduction, installation, and operation management of the British SC001' and Yugoslavian TRANSYT-7P traffic information control systems; Shanghai established a joint taxi dispatch company and set up an industry-wide GPS dispatch center. In my country's transportation sector, the combination of GPS and wireless communication technology has begun to be widely applied to alarm and positioning monitoring of armored trucks, and command and dispatch of police cars, fire trucks, and ambulances. Some cities' taxi, car rental, and logistics industries have begun to use GPS technology for vehicle monitoring, tracking, and dispatch management, rationally distributing vehicles to respond to user requests as quickly as possible, reducing energy consumption, and saving operating costs. In vehicle navigation, GPS vehicle monitoring systems establish digital radio stations in cities to broadcast real-time traffic information. Onboard equipment uses GPS for precise positioning, combined with electronic maps and real-time traffic information, to automatically match the optimal route and achieve automatic vehicle navigation. In summary, GPS technology is already quite mature in the application of transportation systems. Therefore, it is feasible to apply GPS technology to the real-time display and positioning of public buses in my country. [b]Key Technologies[/b] 1. GPS Dynamic Positioning GPS positioning can be divided into static positioning and dynamic positioning based on the motion state of the point to be determined. In a broad sense, GPS dynamic positioning is GPS navigation, such as for navigation of land, water and aerospace vehicles. Depending on the purpose and accuracy requirements of the application, GPS dynamic positioning methods are also different. They are mainly divided into the following types: single-point dynamic positioning, real-time differential dynamic positioning, and post-processing differential dynamic positioning. This system adopts the single-point dynamic positioning method, in which the vehicle-mounted GPS terminal autonomously measures the real-time position of the moving target and sends this position information to the monitoring center through a wireless communication system. The monitoring center then draws the trajectory of the moving target to realize real-time vehicle monitoring and the collection of various information. 2. Application of GIS in Vehicle Monitoring GIS is an emerging interdisciplinary field that integrates surveying and mapping science and technology, database technology and computer graphics technology. In the field of vehicle monitoring, GIS is an information system that integrates urban geographic information systems and landmark thematic information for vehicle navigation and tracking. It can display electronic maps at various scales, quickly and reliably provide vehicles with various query information, flexibly and conveniently select the optimal driving route between any two nodes on the road network, and perform real-time tracking and dispatch management of vehicles from the monitoring center. The main functions of GIS technology in vehicle monitoring systems include: providing a user-friendly graphical interface, displaying road condition information with different markers to remind drivers; allowing users to arbitrarily zoom in, zoom out, pan, rotate, and display in layers on vector electronic maps; displaying the vehicle's location accurately and in real-time on the electronic map, tracking the vehicle's driving process, and replaying the vehicle's trajectory; allowing users to query geographic entities; and enabling users to perform route planning and shortest path selection on the electronic map. 3. Coordinate Transformation in Vehicle Monitoring Systems Generally, transformations between planar coordinate systems include similarity transformations, affine transformations, bilinear transformations, and quadratic and cubic polynomial transformations. Similarity transformation is a transformation between two planar coordinate systems without considering systematic errors; affine transformation takes into account the difference in scale factors of the longitudinal and abscissas on the basis of similarity transformation. In order to eliminate and reduce the errors caused by translation, rotation, scaling, Earth curvature and Earth projection between the two coordinate systems, it is generally necessary to establish a mapping relationship between them using quadratic or higher-order curve equations. In the vehicle positioning system, Equation 1) can generally meet the requirements of vehicle dynamic positioning for coordinate transformation. U=a0+a1x+a2y (1) V=b0+b1x+b2y 4 Vehicle navigation data transmission based on serial communication technology There are three common methods for implementing serial communication using Delphi 7.0: one is to use controls, such as MSCOMM control, SPCOMM control and Cport3.0 control; the second is to use API functions; the third is to call other serial communication programs. Among them, it is more complicated to write serial communication programs using APIs, which requires mastering a lot of communication knowledge. In comparison, it is relatively simple to use Cport3.0 control, and this control has rich properties and events closely related to serial communication, providing various operations on the serial port, which is easy to implement. 5. Impact of GSM SMS Delay on Location Data While GSM SMS service can reliably transmit vehicle location information, limitations of the SMS technology itself and varying channel congestion levels result in varying degrees of delay in location data transmission. Experiments show that when SMS messages are transmitted in maximum bytes, the cumulative probability distribution of a 5-second one-way transmission delay can reach 92.80%. For low- and medium-speed mobile terminals, this delay is generally sufficient for monitoring and navigation applications. However, for high-speed moving objects, a delay of 3-5 seconds may be too long. For example, a car traveling at 120 km/h would have traveled 167 meters in 5 seconds. By the time the location data reaches the monitoring center, there would be an accumulated error of 167 meters. In a city with its crisscrossing streets and numerous intersections, this error would significantly reduce the reliability of the data as a decision-making reference. The main method to reduce latency from mobile terminals is to reduce the size of each data transmission. If the data transmission size is reduced to 70 bytes, the theoretically calculated transmission delay is 1.9 seconds. Further reducing the data size will also reduce transmission latency. When transmitting GPS positioning and navigation data using the NMEA-0183 format, we first process the data, packaging only the longitude, latitude, and time into short SMS data packets to minimize transmission latency. Additionally, dead reckoning can be performed on vehicles, further improving the real-time accuracy of vehicle monitoring. System Cost Estimation This paper combines GPS, GIS, computer data processing technology, and modern data communication technology to research a vehicle monitoring system. A preliminary GPS vehicle monitoring system with all-weather satellite positioning, electronic map display, and real-time vehicle monitoring capabilities has been developed. Editor: He Shiping