The steel-aluminum composite contact rail system for urban rail transit is also called the three-track system.

It is a device that transmits electrical energy to the subway and urban rail transit system electric traction vehicles through the collector shoe. According to the different ways of drawing current from the current collector shoe from the contact rail, the instaIlation methods of the contact rail can be divided into three methods: upper contact, lower contact and side contact. The contact rail system is mainly composed of steel aluminum composite rails, expansion joints, end elbows, ordinary joints, electrical connection clamps, central anchor clamps and other related components and insulating support devices, which provide electric power for electric locomotives.
The steel-aluminum composite rail system has a series of characteristics such as good electrical conductivity large carrying capacity, light weight, convenient installation, corrosion resistance, good wear resistance, and long service life. Compared with the traditional overhead catenary system, it has better safety performance and the advantages of smaII impact on the urban landscape. The use of steel-aluminum composite rail system greatly reduces the workload of design, construction, installation, operation and maintenance, and has significant economic and social benefits.

Upper contact

Following the tradition, the design of the power receiving shoe is simpler, and the contact rail is installed on the side of the running rail for easy installation.

Bottom contact 

Higher safety, better protection performance, live contact rail is not easy to be touched unconsciously, which can ensure personal safety.