A passenger railroad car or passenger car (American English), also called a passenger carriage, passenger coach (British English and International Union of Railways), or passenger bogie (Indian English) is a railroad car that is designed to carry passengers. The term passenger car can also be associated with a sleeping car, a baggage car, a dining car, railway post office and prisoner transport cars.

The first passenger cars were built in the early 1800s with the advent of the first railroads, and were small and little more than converted freight cars. Early passenger cars were constructed from wood; in the 1900s construction shifted to steel and later aluminum for improved strength. Passenger cars have increased greatly in size from their earliest versions, with modern bi-level passenger cars capable of carrying over 100 passengers. Amenities for passengers have also improved over time, with developments such as lighting, heating, and air conditioning added for improved passenger comfort. In some systems a choice is given between first- and second-class carriages, with a premium being paid for the former.

In some countries, such as the UK, coaching stock that is designed, converted or adapted to not carry passengers, is referred to as "NPCS" (non-passenger coaching stock); similarly, in the US, some maintenance (engineering) stock can be known as "MOW" (maintenance of way).

History

19th century: First passenger cars and early development

Up until about the end of the 19th century, most passenger cars were constructed of wood. The first passenger trains did not travel very far, but they were able to haul many more passengers for a longer distance than wagons pulled by horses.

As railways were first constructed in England, so too were the first passenger cars. One of the early coach designs was the "Stanhope". It featured a roof and small holes in the floor for drainage when it rained, and had separate compartments for different classes of travel. The only problem with this design is that the passengers were expected to stand for their entire trip. The first passenger cars in the United States resembled stagecoaches. They were short, often less than  long and had two axles.

British railways had a head start on American railroads, with the first "bed-carriage" (an early sleeping car) being built there as early as 1838 for use on the London and Birmingham Railway and the Grand Junction Railway. Britain's early sleepers, when made up for sleeping, extended the foot of the bed into a boot section at the end of the carriage. The cars were still too short to allow more than two or three beds to be positioned end to end.

Britain's Royal Mail commissioned and built the first travelling post office cars in the late 1840s as well. These cars resembled coaches in their short wheelbase and exterior design, but were equipped with nets on the sides of the cars to catch mail bags while the train was in motion. American RPOs, first appearing in the 1860s, also featured equipment to catch mail bags at speed, but the American design more closely resembled a large hook that would catch the mailbag in its crook. When not in use, the hook would swivel down against the side of the car to prevent it from catching obstacles.

As locomotive technology progressed in the mid-19th century, trains grew in length and weight. Passenger cars, particularly in America, grew along with them, first getting longer with the addition of a second truck (one at each end), and wider as their suspensions improved. Cars built for European use featured side door compartments, while American car design favored what was called a train coach, a single long cabin with rows of seats, with doors located at the ends of the car. Early American sleeping cars were not compartmented, but by the end of the 19th century they were. The compartments in the later sleepers were accessed from a side hall running the length of the cars, similar to the design of European cars well into the 20th century.

Many American passenger trains, particularly the long distance ones, included a car at the end of the train called an observation car. Until about the 1930s, these had an open-air platform at the rear, the "observation platform". These evolved into the closed end car, usually with a rounded end which was still called an "observation car". The interiors of observation cars varied. Many had special chairs and tables.

The end platforms of all passenger cars changed around the turn of the 20th century. Older cars had open platforms between cars. Passengers would enter and leave a car through a door at the end of the car which led to a narrow platform. Steps on either side of the platform were used for getting on or off the train, and one might hop from one car platform to another. Later cars had enclosed platforms called vestibules which together with gangway connections allowed passengers not only to enter and exit the train protected from the elements, but also to move more easily between cars with the same protection.

Dining cars first appeared in the late 1870s and into the 1880s. Until this time, the common practice was to stop for meals at restaurants along the way (which led to the rise of Fred Harvey's chain of Harvey House restaurants in America). At first, the dining car was simply a place to serve meals that were picked up en route, but they soon evolved to include galleys in which the meals were prepared. The introduction of vestibuled cars, which for the first time allowed easy movement from car to car, aided the adoption of dining cars, lounge cars, and other specialized cars.

1900–1950: Transition from wood to steel, new car types

In the early 1900s, safety concerns led the railroad industry to transition from wood to steel construction. Steel was heavier but this transition took place simultaneously with a transition to higher-powered locomotives. The Pennsylvania Railroad began building all-steel passenger cars in 1906 due to concerns about fire in the tunnels it was building to access Manhattan's Pennsylvania Station, which opened in 1910. Other railroads followed because steel cars were safer in accidents. During a transition period, some railroads put steel frames underneath wooden cars.

By the 1920s, passenger cars on the larger standard gauge railroads were normally between  and  long. The cars of this time were still quite ornate, many of them being built by experienced coach makers and skilled carpenters. In the United States, the so-called "chair car" with individual seating became commonplace on long-distance routes.

With the 1930s came the widespread use of stainless steel for car bodies. The typical passenger car was now much lighter than its carbon-steel cousins of old, though still much heavier than nineteenth-century wooden cars. The new "lightweight" and streamlined cars carried passengers in speed and comfort to an extent that had not been experienced to date. Aluminum and Cor-Ten steel were also used in lightweight car construction, but stainless steel was the preferred material for car bodies. Stainless steel cars could be and often were, left unpainted except for the car's reporting marks that were required by law.

By the end of the 1930s, railroads and car builders were debuting car body and interior styles that could only be dreamed of before. In 1937, the Pullman Company delivered the first cars equipped with roomettes – that is, the car's interior was sectioned off into compartments, much like the coaches that were still in widespread use across Europe. Pullman's roomettes, however, were designed with a single traveller in mind. The roomette featured a large picture window, a privacy door, a single fold-away bed, a sink and a small toilet. The roomette's floor space was barely larger than the space taken up by the bed, but it allowed the traveller to ride in luxury compared to the multilevel semiprivate berths of old.

Now that passenger cars were lighter, they were able to carry heavier loads, but the size of the average passenger that rode in them didn't increase to match the cars' new capacities. The average passenger car could not be made any wider or longer due to side clearances along the railroad lines, but they generally could get taller because they were still lower than many freight cars and locomotives. The railroads soon began building and buying dome and bilevel cars to carry more passengers.

1950–present: High-technology advancements

Starting in the 1950s, the passenger travel market declined in North America, though there was growth in commuter rail. Private intercity passenger service in the U.S. mostly ended with the creation of Amtrak in 1971. Amtrak took over equipment and stations from most of the railroads in the U.S. with intercity service.

The higher clearances in North America enabled a major advancement in passenger car design, bi-level (double-decker) commuter coaches that could hold more passengers. These cars started to become common in the United States in the 1960s, and were adopted by Amtrak for the Superliner design as well as by many other railroads and manufacturers. By 2000, double-deckers rivaled single level cars in use around the world.

While intercity passenger rail travel declined in America, ridership continued to increase in other parts of the world. With the increase came an increased use of newer technology on existing and new equipment. The Spanish company Talgo began experimenting in the 1940s with technology that would enable the axles to steer into a curve, allowing the train to move around the curve at a higher speed. The steering axles evolved into mechanisms that would also tilt the passenger car as it entered a curve to counter the centrifugal force experienced by the train, further increasing speeds on existing track. Today, Talgo