A train is a form of rail transport consisting of a series of vehicles that usually runs along a rail track to transport cargo or passengers.
There are various types of trains that are designed for particular purposes. A train may consist of a combination of one or more locomotives and attached railroad cars, or a self-propelled multiple unit. A freight train uses freight cars (also known as wagons or trucks) to transport goods or materials (cargo). Freight and passengers may be carried in the same train in a mixed consist. Rail cars and machinery used for maintenance and repair of tracks, etc., are termed maintenance of way equipment; these may be assembled into maintenance of way trains.
A subway train appears in both the singleplayer and multiplayer of Battlefield 3.
During the campaign, Henry Blackburn broke out of his interrogation with Agent Kovic and Agent Gordon in New York City and jumped onto the roof of a nearby subway train that held Solomon who planned on setting of a nuclear device in the center of the city. After getting inside the train, Blackburn fought through the train and proceed to dispatch Solomon's men before being grounded by Solomon himself. Solomon then travels to the front of the train with Blackburn in pursuit as it is soon revealed that explosives have been planted throughout each train car before detonating. Blackburn and Solomon both survive the blast and proceed to the center of Times Square.
Similar to singleplayer, subway trains appear in multiplayer on the map Operation Métro. The player is unable to operate the trains which remain stationary. They are, however, able to enter each train except their cabs.
Trains appear throughout Battlefield 4.
A small train appears on Golmud Railway. The train itself is flag Delta on Conquest and Conquest Large and moves depending on who controls. The train spawns in the middle of the railway on the map and only moves once it has been captured. Afterwards it will slowly move to the end of the railway closest to the controlling team's deployment before coming to a stop. Each end of the train carries a mounted LMG which can be opperated to defend the objective from nearby enemies.
The train and any of its occupants are extremely vulnerable to attack due to its slow speeds and relatively small turn radius for the mounted LMGs. This makes gunners easy targets for nearby snipers and vehicles. Since the train is an objective, it cannot be destroyed and is able to be used indefinitely. It should be noted that the capture radius for the train includes the area beneath the railway, allowing players to capture and defend it in a safer position.
In Rush a longer train appears stationary in the center of the map and features two M-COM stations on it. Since the train lays in a lower area compared to the surrounding map, both teams have an easy view of the M-COMs, resulting in highly contested firefights for control.
A freight train makes an appearance on the map Propaganda. As the main Levolution for the map, it will periodically travel at high speeds through the railway that runs through the center of the map. In doing so, it will kill and destroy anything it hits. The train's tanker cars are flammable and can be set off by explosives.
A train appears in Battlefield Hardline on the map Train Dodge. Functioning in a similar manner to the Battlefield 4 map on Propaganda, the train will periodically travel on the railway running through the center of the map, killing and destroying anything in its path. Players are now able to vault onto the train and travel down the railway before entering the out of bounds area.