Shanghai Shentong Metro Group builds an intelligent content review system to provide passengers with a green and safe travel space｜Case Study

Written by

Audrey Miles

Updated on:July-16th-2025

In today's society, the subway has become an important way for urban residents to travel on a daily basis. While riding the subway, passengers will frequently interact with the PIS system (passenger information system). The system covers the platform and the interior of the train. Its functions include accurate display of the countdown of the train entering the station, real-time update , accurate delivery of video media advertisements, and timely release of emergency information. The PIS system transmits various key information to a large number of passengers every day. Once the information content is biased or inappropriate, it is very easy to cause widespread public attention and disturbance, thereby causing immeasurable negative impact on the reputation of the subway operator.

Therefore, the importance of PIS system content review is self-evident. Driven by the wave of digitalization, the intelligent review of content with the help of AI technology is gradually becoming a new trend in the development of the industry. With its forward-looking vision and innovative spirit, Shanghai Shentong Metro Group Co., Ltd. (hereinafter referred to as "Shanghai Shentong Metro Group") has taken the lead in exploring this field and become an industry pioneer. Its successful case of cooperation with NetEase Yidun has research value for the digital transformation and content security management of the entire subway industry.

Shanghai Shentong Metro Group hopes to use AI technology to ensure the security and compliance of PIS system information content

Shanghai has the world's largest subway network, with an average daily passenger flow of more than 10 million. This huge passenger flow means that all aspects of subway operations must be extremely demanding. The PIS system of Shanghai Metro transmits various key information to tens of thousands of passengers every day. The high frequency of information release and the wide coverage of the population make it a top priority in subway operations.

The PIS system of Shanghai Metro is built and maintained by Shanghai Shentong Metro Group. The accuracy, security and social impact of its information content are directly related to the passengers' travel experience and the overall image of subway operations. With the vigorous development of artificial intelligence technology, Shanghai Shentong Metro Group has keenly captured the opportunities brought by this technological change. In the context of the AI era, Shanghai Shentong Metro Group hopes to build an efficient, accurate and intelligent content review system with the help of cutting-edge technologies such as natural language processing (NLP), image processing, audio and video recognition and artificial intelligence. The system aims to quickly identify, respond to and feedback on illegal content in the PIS system, provide targeted improvement suggestions, and have automatic alarm and fuse mechanisms, thereby playing a core supporting role in the content security of the public service screen of urban rail transit.

Shanghai Shentong Metro Group and NetEase Yidun jointly established the Shanghai "AI+ (Joint) Innovation Studio", focusing on the complementary advantages of both parties

After carefully evaluating and studying the construction and operation and maintenance solutions for AI content detection and intelligent review systems, Shanghai Shentong Metro Group and NetEase Yidun decided to establish a joint innovation studio to jointly develop and build a PIS content review solution based on AI technology.

Highlight 1: Outstanding product capabilities

The information content of the PIS system includes text, pictures, audio and video, and is often transmitted simultaneously in a combination. The subway group urgently needs a content review system with strong review coverage, high accuracy and rapid review capabilities. The content review system uses cutting-edge technologies such as big data, deep learning, and NLP natural language algorithms to have high-precision identification . Faced with the high-frequency and wide-coverage information transmission of the PIS system every day, the review system can identify a variety of illegal content including violent terrorism, political content, pornography, etc. within milliseconds, analyze video streams in real time, respond quickly and realize automatic alarms and fuses, and effectively avoid serious public opinion events.

Highlight 2: Flexible and highly available, AI-enabled and scalable

The audit system has many advantages, especially in terms of flexibility, scalability, and high availability. For example, in terms of flexibility, the audit system can run in any environment that supports container technology, whether it is a local server, private cloud, or public cloud platform (such as AWS, Azure, Google Cloud, etc.), ensuring the cross-platform compatibility of the system. It has excellent scalability, and its underlying AI technology base built with cutting-edge technologies such as deep learning has reserved sufficient space for future functional expansion and algorithm upgrades , and can continue to evolve with business development and technological updates. High availability is even more prominent. Faced with the high-frequency and wide-coverage information transmission of the Shanghai Metro PIS system every day, the system can run stably, analyze video streams in real time, respond quickly and realize automatic alarms and fuses, ensuring that content security can be effectively protected under any circumstances, avoiding serious public opinion incidents, and strongly supporting the information security of subway operations.

Highlight 3: Keep up with the supervision and keep updating

Government departments will issue new sensitive words from time to time, but they are usually only released to large news and information organizations, and subway companies often have difficulty obtaining them directly. As one of the leading Internet companies with many Internet products for external content promotion (such as NetEase News, NetEase Cloud Music, etc.), NetEase has established a stable docking channel with regulatory agencies, and NetEase can obtain national regulatory instructions and public opinion information in the first place. Once the regulatory policy is updated, NetEase Yidun can quickly assist customers in updating product capabilities, ensure the timeliness and compliance of the content review system, and provide all-round and dynamic security protection for the subway group.

NetEase Yidun overcomes technical difficulties and customizes intelligent audit solutions for Shanghai Shentong Metro Group

NetEase Yidun and Shanghai Shentong Metro Group have cooperated deeply to establish the Shanghai "AI+ (Joint) Innovation Studio" to jointly customize and develop system construction solutions. From the architectural level, the underlying layer integrates cutting-edge technologies to build a solid AI technology foundation. The system comprehensively covers the intelligent review of train operation information, emergency information release and passenger guidance information, corporate publicity and advertising operation information, and strives to ensure zero broadcast accidents.

Figure 1 PIS system content review solution architecture

The technical challenge faced by the project is to improve the accuracy of system recognition. The PIS system integrates advertisements with subway operation information, and each piece of information occupies a small proportion of the screen, which makes it difficult for the review system to identify. When the original video of the advertisement is reviewed separately, the illegal content can be identified, but after being embedded in the large screen, the proportion of illegal information becomes smaller, resulting in inaccurate recognition and the risk of missed judgment.

To overcome this problem, Shanghai's "AI+ (Joint) Innovation Studio" co-created a "screen cropping and review solution". Based on this solution, the system divides the screen into two parts, the left side is the video content, and the right side is the subway operation information, and performs recognition and review separately, thereby significantly improving the recognition accuracy and providing a stronger guarantee for the content security of the PIS system of Shanghai Shentong Metro Group.

The "PIS system content review system based on AI technology" was launched to improve the safety and efficiency of subway information dissemination

After several months of close cooperation, the joint studio successfully built and launched the "PIS system content review system based on AI technology". The system can obtain the original video stream in the PIS system in real time, accurately detect bad content in the screen, such as pornography, politics, violence, terrorism, insults , etc., to ensure the positive impact of information dissemination. Once unsafe content is found, the system will quickly respond to different levels of operations, including direct fuses and alarms, according to the suspected degree of illegal content. The overall response speed is within 5-10 seconds, which effectively solves the problems of large workload of manual review, subjective judgment criteria, and slow response speed.

In addition, the system has completed comprehensive domestic adaptation, including application layer code, GPU, CPU operating system database, etc., avoiding external restrictions and sanctions in key technology fields and ensuring national security and economic development.

At present, the system has been put into engineering application on some lines of Shanghai Metro, and is planned to be further promoted in the future to strengthen the ability to control public opinion in the field of rail transit and provide solid guarantees for the safe operation and good image of urban rail transit.