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A tourist trolley, also called a road trolley, is a rubber-tired bus designed to resemble an old-style streetcar or tram, usually with false clerestory roof. The vehicles are usually fueled by diesel, or sometimes compressed natural gas.
The name refers to the American English usage of the word trolley to mean an electric streetcar. As these vehicles are not actually trolleys, and to avoid confusion with trolley buses, the American Public Transportation Association (APTA) refers to them as "trolley-replica buses". 
Tourist trolleys are used by both municipal and private operators. Municipal operators may mix tourist trolleys in with the regular service bus fleet to add more visitor interest or attract attention to new routes. In many cities tourist trolleys are used as circulators.  Tourist trolleys are also run by private operators to carry tourists to popular destinations.
In San Francisco, tourist trolleys mimic the city's famous cable cars.
Tourist trolleys sometimes operate in places which also have streetcars. For example, tourist trolleys operate in Philadelphia,  which also has actual trolley service. 
Notable operators of tourist-trolley buses:
The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people in five counties in and around Philadelphia, Pennsylvania. It also manages projects that maintain, replace and expand its infrastructure, facilities and vehicles.
The Niagara Frontier Transportation Authority (NFTA) is a New York State public-benefit corporation responsible for the public transportation oversight of Erie and Niagara counties. The NFTA, as an authority, oversees a number of subsidiaries, including the NFTA Metro bus and rail system, the Buffalo-Niagara International Airport, the Niagara Falls International Airport and NFTA Small Boat Harbor. The NFTA Metro bus and rail system is a multi-modal agency, utilizing various vehicle modes, using the brand names: NFTA Metro Bus, NFTA Metro Rail, NFTA Metrolink and NFTA PAL. In 2022, the system had a ridership of 14,061,700 or about 53,000 per weekday as of the fourth quarter of 2022. In addition, the NFTA also owns and manages a number of properties, including the Buffalo Metropolitan Transportation Center in Downtown Buffalo ; the Niagara Falls Transportation Center on Factory Outlet Boulevard; the Portage Road Transit Center in Niagara Falls; and a number of strategically located bus loops and transit centers in the Buffalo Niagara region. Of note, many of the bus loops have been in continuous operation since the days of the International Railway Company, a predecessor to the NFTA. Agency-wide, the NFTA employs 1,500 full-time and part-time employees. There are three business centers that operate as the NFTA organization: Surface Transportation, which handles ground transportation throughout Erie and Niagara counties, Aviation, which handles air related business at the Buffalo-Niagara International Airport and Niagara Falls International Airport and Property Risk/Management, which operates the NFTA-Boat Harbor and handles other properties that are owned and/or operated by the NFTA.
Buffalo Metro Rail is the public transit rail system in Buffalo, New York, operated by the Niagara Frontier Transportation Authority (NFTA). The system consists of a single, 6.4-mile-long (10.3 km) light rail line that runs for most of the length of Main Street from KeyBank Center in Canalside to the south campus of the University at Buffalo in the northeast corner of the city. The first section of the line opened in October 1984; the current system was completed in November 1986. In 2022, the system had a ridership of 2,386,400, or about 8,400 per weekday as of the fourth quarter of 2022.
The Hamilton Street Railway commonly known as the HSR is a public transport agency in Hamilton, Ontario, Canada. The name is a legacy of the company's early period, when public transit in Hamilton was primarily served by streetcars. Although streetcars are no longer used in the city today, the HSR operates bus and paratransit services, with a ridership of 21 million passengers a year. The HSR uses the Presto card as its method of fare payment, allowing for connections with GO Transit and other transit systems in the Greater Toronto area.
Transportation in Philadelphia involves the various modes of transport within the city and its required infrastructure. In addition to facilitating intracity travel, Philadelphia's transportation system connects Philadelphia to towns of its metropolitan area and surrounding areas within the Northeast megalopolis.
The Massachusetts Bay Transportation Authority (MBTA) operates 152 bus routes in the Greater Boston area. The MBTA has a policy objective to provide transit service within walking distance for all residents living in areas with population densities greater than 5,000 inhabitants per square mile (1,900/km2) within the MBTA's service district. Much of this service is provided by bus. In 2022, the system had a ridership of 83,623,600, or about 275,600 per weekday as of the fourth quarter of 2022.
Toronto Transportation Commission (TTC) was the public transit operator in Toronto, Ontario, Canada, beginning in 1921. It operated buses, streetcars and the island ferries. The system was renamed the Toronto Transit Commission (TTC) in 1954.
The Boston-area trolleybussystem forms part of the public transportation network serving Greater Boston in the U.S. state of Massachusetts. It opened on April 11, 1936, and since 1964 has been operated by the Massachusetts Bay Transportation Authority (MBTA). The current system consists of the Silver Line (Waterfront), a bus rapid transit service using dual-mode buses which run as trolleybuses in a tunnel in the Seaport District of Boston before switching to diesel power to serve other destinations.
As with many large cities, a large number of Boston-area streetcar lines once existed, and many continued operating into the 1950s. However, only a few now remain, namely the four branches of the Green Line and the Ashmont–Mattapan High-Speed Line, with only one running regular service on an undivided street.
The Capital District Transportation Authority (CDTA) is a New York State public-benefit corporation overseeing a number of multi-modal parts of public transportation in the Capital District of New York State. CDTA runs local and express buses, including three lines of an express bus service called BusPlus, and day-to-day management of three Amtrak stations in the Capital region–the Albany-Rensselaer, Schenectady and Saratoga Springs Amtrak stations. In 2022, the system had a ridership of 13,109,300, or about 45,500 per weekday as of the fourth quarter of 2022.
Streetcars were part of the public transit service in Kenosha, Wisconsin in the first third of the 20th century, and returned to this role in 2000.
The Erie Metropolitan Transit Authority (EMTA) is the Municipal Authority that owns and operates the public transport system in Erie County, Pennsylvania which includes the 'e', the area's transit buses; LIFT, the county paratransit service; and Bayliner Trolley, the downtown circulator.
The International Railway Company (IRC) was a transportation company formed in a 1902 merger between several Buffalo-area interurban and street railways. The city railways that merged were the West Side Street Railway, the Crosstown Street Railway and the Buffalo Traction Company. The suburban railroads that merged included the Buffalo & Niagara Electric Street Railway, and its subsidiary the Buffalo, Lockport & Olcott Beach Railway; the Buffalo, Depew & Lancaster Railway; and the Niagara Falls Park & River Railway. Later the IRC acquired the Niagara Gorge Railroad (NGRR) as a subsidiary, which was sold in 1924 to the Niagara Falls Power Company. The NGRR also leased the Lewiston & Youngstown Frontier Railroad.
The Philadelphia Transportation Company (PTC) was the main public transit operator in Philadelphia, Pennsylvania, from 1940 to 1968. A private company, PTC was the successor to the Philadelphia Rapid Transit Company (PRT), in operation since 1902, and was the immediate predecessor of the Southeastern Pennsylvania Transportation Authority (SEPTA).
Watertown Carhouse is a bus maintenance facility and former streetcar carhouse located in the southern section of Watertown, Massachusetts, across the Charles River from Watertown Square. As Watertown Yard, the site also serves as a bus depot serving local and express routes, with additional connections available at Watertown Square on the opposite end of the Watertown Bridge.
SEPTA Route 75 is a trackless trolley route operated by SEPTA in North and Northeast Philadelphia, Pennsylvania, United States. It connects to the Market–Frankford Line at Arrott Transportation Center Station, and runs primarily along Wyoming Avenue. Route 75 connects to the Wyoming local line and goes to Wayne Junction in Nicetown.
SEPTA Route 29 is a former streetcar and trackless trolley line and current bus route, operated by the Southeastern Pennsylvania Transportation Authority (SEPTA) in South Philadelphia, Pennsylvania, United States. The line runs between the Gray's Ferry neighborhood and the vicinity of Pier 70 along the Delaware River.
The Vancouver trolley bus system forms part of the TransLink public transport network serving Metro Vancouver in the Canadian province of British Columbia. In operation since 1948, the system presently comprises 13 routes and is managed by the Coast Mountain Bus Company, a subsidiary of TransLink. It uses a fleet of 262 trolley buses, of which 74 are articulated vehicles.
The Seattle trolleybus system forms part of the public transportation network in the city of Seattle, Washington, operated by King County Metro. Originally opened on April 28, 1940, the network consists of 15 routes, with 174 trolleybuses operating on 68 miles (109 km) of two-way parallel overhead lines. As of the fourth quarter of 2022, the system carries riders on an average of 35,400 trips per weekday, comprising about 18 percent of King County Metro’s total daily ridership. At present in Seattle, a very common alternative term for trolleybus is trolley.
The Philadelphia trolleybus system forms part of the public transportation network serving Philadelphia, in the state of Pennsylvania, United States. It opened on October 14, 1923, and is now the second-longest-lived trolleybus system in the world. One of only five such systems currently operating in the U.S., it presently comprises three lines, and is operated by the Southeastern Pennsylvania Transportation Authority (SEPTA), with a fleet of 38 trolleybuses, or trackless trolleys as SEPTA calls them. The three surviving routes serve North and Northeast Philadelphia and connect with SEPTA's Market–Frankford rapid transit line.