Due to the nature of short commuter flights, flying regional jets are very expensive to operate because jet aircraft are better utilized on longer flights. This is due to jet aircraft being designed to operate most efficiently when flying above 25,000 feet. However on most short flights, such as Milwaukee to Chicago, these same aircraft might only reach 10,000 feet. Additionally, jet aircraft have thesame ground processing times of 20-30 minutes no matter the flight length; which leads to lower overall aircraft utilization. Meanwhile, a train can make a stop in a city that lasts only a minute. Therefore trains are best utilized for shorter, higher-volume stage lengths. Although trains might be more expensive, when operating small loads and this is what causes arguments about the value of trains. For example:
- Example: 1 engine & 1 passenger coach with 72 seats = ( 60¢ per Available Seat Mile)
Note: Diesel Multiple Units (MDUs) might offer a low cost alternative (used in Britain)
However, while the fixed costs of operating a train are higher than a bus or a small airplane; trains become very efficient at greater loads. This is due the fact that the incremental cost of adding more passengers is very low. For example, if a train that operated with only 72 seats adds more coaches, that train then become cheaper to operate on a per seat basis. For example:
- Example: 1 engine & 5 coaches with 360 seats ( 12.1¢ per Available Seat Mile)
Additionally, unlike airplanes and busses, train capacities can be adjusted higher/lower rather easily by adding or disconnecting coaches; or even hitching individual trains together.