Construction of Train Traffic Monitoring Systems Using SVG

Hideo Nakata*, Masayo Osaki*, Teruhiko Teraoka* and Tadashi Yamamura**

*Advanced Technology R&D Center, Mitsubishi Electric Corporation

**Transportation Systems Center, Mitsubishi Electric Corporation

Graphical train traffic monitoring systems are indispensable for accurate service. Recently, such systems are required not only in central supervision rooms but also in stations, on platforms, and in construction sites for railway tracks. In many cases, various portable terminals that implement web applications are used as clients. SVG technology is effective in train traffic monitoring systems.

The main graphic screens of train traffic monitoring systems show two kinds of diagrams: train tracks and train schedules. The former indicates the actual layout of railway tracks, signals, stations, and so on. On the other hand, the latter consists of lines which correspond to the movements of trains, train numbers for each train line, and horizontal lines which show the positions of stations.

Train track diagrams indicate the current position of trains, the condition of signals, the direction of switches, and so on, using simplified drawings of actual railway tracks and signals. To notify operators of this information, the color of tracks and signals are displayed using SVG, and a train's number is displayed in text that dynamically changes according to supervisory data. This paper shows how to automatically update figures and characters on screens without pushing a renewal button of a web browser. Furthermore, by updating only the changed parts on the screens, the proposed system improves updating speed and reduces perceptible flickers.

Train schedule diagrams are charts that illustrate train movements in actual time depicted along a horizontal axis. The diagrams must indicate thousands of train lines by scrolling. Therefore, we improved scrolling functions and added mechanisms to change the indication of train lines according to the train schedule. When a train schedule diagram is converted into a SVG file, train lines and various marks are subdivided in the shape of lattices, grouped together, labeled, and outputted to a definition sentence (def tag). The function uses the rectangle of SVG which receives mouse events and is able to choose train lines and various marks using the above described labels. It displays them according to the movement of the scroll bar slider or changes in the plan.

SVG has many advantages over bitmapped graphics: it can be scaled to a desired size, and file size is also small. By using SVG, we propose a particularly effective implementation method for web applications. We will expand our proposed system to control and operate train services interactively on the graphic screen of web browsers.