A commuter train is a train designed to carry large numbers of people over short to medium distances, generally on their way between home and work (commuters).

It is usually optimized for maximum passenger volume, in most cases, without sacrificing comfort and luggage space, though commuter trains seldom have the amenities of long distance trains. The general range of commuter trains varies between 15 and 100 miles (24 to 160 km), with operating speeds between 60 and as fast as 110 mi/h (95 - 175 km/h).

Average speeds vary, but most can be expected to average 33 - 60 mi/h (55 to 95 km/h).

Passenger coaches are either single or double-level cars, with a capacity of between 80 - 110 for single level cars and 145 - 170 for double-level cars.

Many of the coaches are equipped with a control cab, which will allow "push-pull" operation, which means that at the end of the line, the engineer/driver walks from the locomotive to the other end of the train, where the cab control car is located in the train. He then enters the cab, sets up the controls for operation and the locomotive pushes the train the other way, for the return trip.

In this way, it is unnecessary for the locomotive to uncouple and "runaround" the train, recouple and then make the pull. Or, if there's no "runaround" track, the train would have to be "wyed", which is the functional equivalent of a three -point turn into a driveway to reverse direction, whilst driving.

If they are electric trainsets, which are electric multiple units (EMUs), almost all have control cabs at both ends.

See also the terminus section of train station about this.

If they are locomotive-hauled trainsets, the locomotives can be either electric or diesel-electric, although some countries, such as Germany and some of the former Soviet-bloc countries use diesel hydraulic locomotives.

Commuter trains differ from metros, in general, by

  • being larger;
  • having a lower frequency of service (in most cases);
  • having scheduled service (trains at specific hours rather than at specific intervals); and
  • serving lower-density areas, such as by connecting suburbs with the city centre.

They run on standard gauge track, defined as 4 ft. 8 1/2 inches (1435 mm), although there are narrow and broad gauge commuter trains. The narrow gauge trains generally use 3 ft. 6" gauge (1067 mm) or "meter gauge" (39.37 inches). Examples of countries using narrow gauge are Japan, Switzerland and India. Broad gauge trains generally use a gauge of 5 ft. 2" (1535 mm). Argentina, Russia (and Baltic Republics), Spain and Brazil use broad gauge, in some cases.

In some cases, hybrids between a train and a metro have been created. They run underground in the dense metropolitan center while they run on ordinary outdoors tracks in lower-density areas. Examples include the Paris RER and the San Francisco BART.

Development of commuter trains has become popular today, with the increased public awareness of congestion, dependence on fossil fuels, environmental issues and rising automobile costs.

In Germany, a commuter train is known as an S-Zug.

See also: Public transport, Regional rail.