<br> To begin with, the electric railway needs a power provide that the trains can entry always. Figure 3: Docklands Light Railway train with third rail bottom contact electrification system. An example of a bottom contact shoe as used on the Dockland Light Railway line in London is shown in Figure three and within the video (Figure 5). Some prime contact techniques have additionally used spring loading however they are mechanically tougher to regulate because of the hunting motion of the bogie and the danger that the shoes will get trapped beneath the head of the rail and turn it over. There needs to be an entire circuit, from the source of the vitality out to the consuming item (gentle bulb, cooking stove or prepare) and back to the source, so a return conductor is required for our railway. The gaps are usually marked by a sign or a gentle which indicates if the current is on within the part ahead. AC methods always use overhead wires, DC can use both an overhead wire or a 3rd rail
