How do railroad tracks work?
A railroad track consists of two parallel steel rails set a fixed distance apart, called the gauge. The rails are connected to each other by railroad ties (called sleepers in Europe), which may be made of wood or concrete. The rails are usually bolted to the ties. The ties are set into the loose gravel or ballast.
How do railway tracks expand?
When temperatures rise, steel tracks will expand, meaning they get longer. Heat-related expansion places a lot of stress on the ties, ballasts, and rail anchors that keep the tracks fixed to the ground. Slower moving trains exert less additional force on the tracks, which helps to prevent buckling.
How do railroad track switches work?
When the wheels reach the switch, the wheels are guided along the route determined by which of the two points is connected to the track facing the switch. If the right point is connected, the right wheel’s flange will be guided along the rail of that point, and the train will continue along the straight track.
Do railroad tracks have electricity?
As a result, electrified rail is currently used on less than 1 percent of U.S. railroad tracks while electricity supplies more than one-third of the energy that powers trains globally.
Are railroad tracks welded together?
Most modern railways use continuous welded rail (CWR), sometimes referred to as ribbon rails. In this form of track, the rails are welded together by utilising flash butt welding to form one continuous rail that may be several kilometres long. Thermite welding is used to repair or splice together existing CWR segments.
Why gaps are left in railway tracks?
The gaps left between successive rails on a railway track, the reason is that the rails expand in summer. The gap is provided to allow for this expansion. If no gap is left, the expansion in summer will cause the rails to bend sideways. That will result in train accidents.
Why do train tracks have voltage?
Simple railroad signals historically used the potential (voltage) difference between the track rails to determine if trains were present at certain locations. In addition to maintaining electric isolation between the sections of track, these insulated joints maintained structural integrity.
What are the factors that affect a railroad track?
One of these factors is the correct use of rail joints when fastening multiple lengths of rail together with a fishplate. Another important factor is the the tension in the rail. Temperature can have dramatic effects on railroad tracks when the metal in the rail expands or contracts, having the potential to cause the track to buckle or separate.
How does a track circuit work on a train?
Signals are transmitted to the cab of the train, and are not present next to the tracks except at switches. Each block has a track circuit which determines whether a train is present. Track circuits work by running a circuit using the rails to connect a power source at one end of the block with a relay at the far end.
What kind of rail is used to lay train tracks?
When rail workers are laying train tracks, they often use a flat-bottom steel rail that resembles the steel I-beam girders of construction. The rail has a wide base or foot, a narrow web and a head (wider than the web, but not as wide as the foot).
How are blocks divided on a railroad track?
Each block is divided from the adjacent blocks by an insulated joint between rails. Blocks often have signals at each end to control train movements. Signals are transmitted to the cab of the train, and are not present next to the tracks except at switches.