Pareto efficiencyPareto efficiency or Pareto optimality is a situation where no action or allocation is available that makes one individual better off without making another worse off. The concept is named after Vilfredo Pareto (1848–1923), Italian civil engineer and economist, who used the concept in his studies of economic efficiency and income distribution. The following three concepts are closely related: Given an initial situation, a Pareto improvement is a new situation where some agents will gain, and no agents will lose.
Double-track railwayA double-track railway usually involves running one track in each direction, compared to a single-track railway where trains in both directions share the same track. In the earliest days of railways in the United Kingdom, most lines were built as double-track because of the difficulty of co-ordinating operations before the invention of the telegraph. The lines also tended to be busy enough to be beyond the capacity of a single track. In the early days the Board of Trade did not consider any single-track railway line to be complete.
Allocative efficiencyAllocative efficiency is a state of the economy in which production is aligned with consumer preferences; in particular, the set of outputs is chosen so as to maximize the wellbeing of society. This is achieved if every good or service is produced up until the last unit provides a marginal benefit to consumers equal to the marginal cost of production. In economics, allocative efficiency entails production at the point on the production possibilities frontier that is optimal for society.
Tramway trackTramway track is used on tramways or light rail operations. Grooved rails (or ) are often used to provide a protective flangeway in the trackwork in city streets. Like standard rail tracks, tram tracks consist of two parallel steel rails. Tram rails can be placed on several surfaces, such as with on sleepers like railway tracks, or with grooved rails on concrete sleepers into street surfaces (pavement) for street running. Tram rails in street have the disadvantage that they pose a risk to cyclists.
Sleeping carThe sleeping car or sleeper (often wagon-lit) is a railway passenger car that can accommodate all passengers in beds of one kind or another, for the purpose of sleeping. George Pullman was the American innovator of the sleeper car. The first such cars saw sporadic use on American and English railways in the 1830s; they could be configured for coach seating during the day. Possibly the earliest example of a sleeping car (or bed carriage, as it was then called) was on the London & Birmingham and Grand Junction Railways between London and Lancashire, England.
TrainA train (from Old French trahiner, from Latin trahere, "to pull, to draw") is a series of connected vehicles that run along a railway track and transport people or freight. Trains are typically pulled or pushed by locomotives (often known simply as "engines"), though some are self-propelled, such as multiple units. Passengers and cargo are carried in railroad cars, also known as wagons. Trains are designed to a certain gauge, or distance between rails.
Siding (rail)A siding, in rail terminology, is a low-speed track section distinct from a running line or through route such as a main line, branch line, or spur. It may connect to through track or to other sidings at either end. Sidings often have lighter rails, meant for lower speed or less heavy traffic, and few, if any, signals. Sidings connected at both ends to a running line are commonly known as loops; those not so connected may be referred to as single-ended or dead-end sidings, or (if short) stubs.
Productive efficiencyIn microeconomic theory, productive efficiency (or production efficiency) is a situation in which the economy or an economic system (e.g., bank, hospital, industry, country) operating within the constraints of current industrial technology cannot increase production of one good without sacrificing production of another good. In simple terms, the concept is illustrated on a production possibility frontier (PPF), where all points on the curve are points of productive efficiency.
