There were also combination dome-observation cars built which were meant to be the last car on the train, with both rear observation and the dome up top. Dome observation cars came in both round end, and square end versions. The Union Pacific, in the US, was the primary user of square-end observation cars, prior to Amtrak, although the Burlington Route had several square-end cars of stainless steel. Double-decker or bilevel coach As passenger car construction improved to the point where dome cars were introduced, some passenger car manufacturers began building double decker passenger train cars for use in areas that are more heavily populated or to carry more passengers over a long distance while using fewer cars (such as Amtrak's Superliner cars). Cars used on long-distance passenger trains could combine features of any of the basic car types, while cars used in local commuter service are often strictly coach types on both levels. Double decker coaches were tried in the UK (SR Class 4DD) but the experiment was unsuccessful because the restricted British loading gauge resulted in cramped conditions. Drovers' car Drovers' cars were used on long distance livestock trains in the western United States. The purpose of a drovers' car was to accommodate the livestock's handlers on the journey between the ranch and processing plant. They were usually shorter, older cars, and equipped with stove heaters, as no trainline steam heating was provided. Hospital car A variety of hospital trains operate around the world, employing specialist carriages equipped as hospital wards, treatment rooms, and full-scale operating theatres (US: operating rooms). Narragansett-style excursion car Narragansett-style excursion cars are open-air passenger cars with cross-bench seating first popularized by railroads in New England. Current operating examples of these passenger cars can be found on the Disneyland Railroad in California and on the Walt Disney World Railroad in Florida. Similar coaches are also found on the Western River Railroad in Tokyo Disneyland. Private car Many cars built by Pullman and other companies were either originally built or later converted for use as business and private cars which served as the "private jet" of the early-to-mid-20th century. They were used by railroad officials and dignitaries as business cars, and wealthy individuals for travel and entertainment. There are various configurations, but the cars generally have an observation platform and include a full kitchen, dining room, state rooms, secretary's room, an observation room, and often servant's