Explanation: While 'metro' is a common term, rapid transit systems are also known by various other names globally, including 'subway,' 'U-Bahn,' 'heavy rail,' 'MRT,' and 'el train,' depending on the region and system characteristics.

Explanation: In most of Britain, the term 'subway' typically refers to a pedestrian underpass. The underground rail system in London is known as the 'Underground' or the 'Tube'.

Explanation: The meaning of 'MRT' varies by country. For example, in Indonesia it stands for 'Moda Raya Terpadu,' and in the Philippines, it means 'Metro Rail Transit'.

Explanation: Commuter rail systems typically operate at lower frequencies with more widely spaced stations than urban rapid transit, allowing for higher average speeds over longer distances.

Explanation: A 'premetro' design is a hybrid approach that builds an underground rapid transit system in the city center while utilizing a light rail or tram system in the suburbs.

Explanation: The London Underground is specifically known as the 'Underground' or 'Tube.' In most of Britain, 'subway' refers to a pedestrian underpass.

Explanation: Mass rapid transit (MRT), rail rapid transit (RRT), and heavy rail are all common alternative names for rapid transit. Light rail transit (LRT), while related, is a distinct category of urban rail, often with different operational characteristics.

Explanation: In Indonesia, the acronym 'MRT' stands for 'Moda Raya Terpadu,' which translates to 'Integrated Mass Transit Mode'.

Explanation: In North America, elevated systems are often called 'the El' or 'the L,' with the Chicago 'L' being a prominent example.

Explanation: In most of Britain, the term 'subway' typically refers to a pedestrian underpass, not an underground rail system like the London 'Underground' or 'Tube'.

Explanation: In Italy, the term 'metropolitana' is used for rapid transit systems found in cities such as Rome, Milan, and Naples.

Explanation: A key difference is that commuter rail systems typically operate at lower frequencies with more widely spaced stations, allowing for higher average speeds to serve outer suburbs, whereas urban rapid transit has high frequency and frequent stops.

Explanation: Although technically commuter rail, systems like German S-Bahns and the Mumbai Suburban Railway provide frequent mass transit within the city, effectively functioning as a substitute for a dedicated rapid transit system.

Explanation: In Germany and Austria, 'U-Bahn' systems are frequently supported by 'S-Bahn' systems, which are typically suburban rail networks that integrate with the urban rapid transit.

Explanation: In large French cities such as Paris, Marseille, and Lyon, the term 'métro' is used for their rapid transit systems.

Explanation: Paris, Lille, and Amsterdam all use the term 'métro' or 'metro'. Berlin, being in Germany, uses the term 'U-Bahn' for its rapid transit system.

Explanation: The source material lists Berlin, Hamburg, Munich, and Nuremberg as German cities with U-Bahn systems, but does not mention Frankfurt.

Explanation: In addition to 'el trains' and 'skytrains,' elevated rapid transit systems are also referred to by terms such as 'overhead,' 'overground,' or 'Hochbahn' in German.

Explanation: Elevated rapid transit systems are often called 'el trains,' which is a shortened form of the word 'elevated'.

Explanation: The Metropolitan Railway, which opened in 1863, was initially powered by steam locomotives. The world's first electric-traction rapid transit railway was the City & South London Railway, which opened later in 1890.

Explanation: New York's first elevated railway, which opened in 1868, was initially a cable-hauled line powered by stationary steam engines, not electric motors.

Explanation: The City & South London Railway, the world's first electric-traction rapid transit system, was intended to be called the 'City and South London Subway,' thereby introducing the term into railway terminology.

Explanation: The first stretch of underground urban railway in Latin America opened in Buenos Aires in 1913, not Rio de Janeiro.

Explanation: The world's first rapid transit system, the Metropolitan Railway in London, opened to the public in 1863.

Explanation: Early experiences with steam-hauled rapid transit, such as London's Metropolitan Railway, were unpleasant due to significant ventilation issues caused by the steam engines.

Explanation: New York's first elevated railway, opened in 1868, was initially a cable-hauled line powered by stationary steam engines.

Explanation: The City & South London Railway, which opened in 1890, was intended to be called the 'City and South London Subway,' thereby introducing the term 'Subway' into railway terminology.

Explanation: The first stretch of underground urban railway in Latin America opened in Buenos Aires in 1913 as part of Line A of the Buenos Aires Underground.

Explanation: The 'hump' technique involves designing tracks with a dip between stations, allowing gravity to assist trains as they accelerate and brake, which improves energy efficiency and operational performance.

Explanation: Elevated railways experienced a resurgence in popularity in the last quarter of the 20th century because they are a cheaper and easier alternative to building expensive tunnels.

Explanation: The two primary methods for constructing underground rapid transit lines are 'cut-and-cover' and 'bored tunneling'.

Explanation: The 'cut-and-cover' method involves excavating a trench in a city street, constructing a tunnel structure within it, and then refilling the trench to restore the roadway.

Explanation: A key benefit of tunneling is that it moves traffic away from street level, freeing up valuable land for buildings and other uses, which is particularly advantageous in areas with high land prices.

Explanation: The 'hump' technique, where tracks dip between stations, is designed to improve energy efficiency and operational performance by using gravity to assist with acceleration and braking.

Explanation: Elevated railways saw a resurgence in popularity because they are a cheaper and easier alternative to constructing expensive tunnels, especially in areas with challenging ground conditions like high water tables.

Explanation: Bored tunneling minimizes surface disruption compared to cut-and-cover, but it can be complicated by factors such as encountering groundwater or needing to blast through bedrock.

Explanation: Rubber-tired rapid transit systems have higher maintenance costs and are less energy-efficient than conventional systems, although they offer quieter operation and can handle steeper inclines.

Explanation: Grade of Automation 4 (GoA 4), or unattended train operation (UTO), signifies completely unstaffed trains where all operational functions are automated.

Explanation: Virtually all modern rapid transit trains are electric, with traction power supplied through one of two main forms: an overhead line or a third rail mounted at track level.

Explanation: A significant obstacle to converting existing lines to fully automated operation is the potential necessity for a complete shutdown of services during the conversion process.

Explanation: A third rail, which is a conductor rail mounted at track level and contacted by a sliding 'pickup shoe,' is one of the two main methods for supplying traction power to electric rapid transit trains.

Explanation: A major obstacle to automating existing rapid transit lines is the potential need for a complete shutdown of service during the conversion process, which can be highly disruptive.

Explanation: While most systems use conventional rail, some employ alternative technologies like guided rubber tires, maglev, or monorails. Diesel engines are not used due to ventilation and environmental concerns in urban systems.

Explanation: Grade of Automation 4 (GoA 4), or Unattended Train Operation (UTO), signifies completely unstaffed trains where all operational functions are automated without any crew on board.

Explanation: Grade of Automation 2 (GoA 2), or Semi-automatic Train Operation (STO), involves a crew member who is responsible for door closure while the train's movement is automated.

Explanation: Grade of Automation 3 (GoA 3), or Driverless Train Operation (DTO), features a 'passenger service agent' on board who is not actively driving but manages doors and assists passengers.

Explanation: Disadvantages of rubber-tired rapid transit systems include higher maintenance costs and lower energy efficiency compared to conventional steel-wheel systems.

Explanation: The two main forms of delivering traction power to electric rapid transit trains are an overhead line and a third rail mounted at track level.

Explanation: A fundamental characteristic of modern rapid transit systems is their operation on an exclusive right-of-way, which ensures that their tracks are not accessible to pedestrians or other vehicles.

Explanation: Rapid transit systems are generally integrated with other forms of public transport, such as buses or trams, and are often operated by the same public transport authorities to create a cohesive network.

Explanation: Rapid transit systems are designed for local transport within urban areas, aiming to efficiently move large numbers of people over short distances at high frequency.

Explanation: While platform screen doors (PSDs) can contribute to reducing ventilation costs, their primary function is to enhance safety by preventing people from falling onto the tracks.

Explanation: The capacity of a rapid transit line is determined by the product of three factors: the capacity of each car, the number of cars per train (train length), and the number of trains per hour (service frequency).

Explanation: While a single corporate image may exist for the entire transit authority, the rapid transit component typically has its own distinct logo for easy recognition.

Explanation: The primary functions of rapid transit stations are to allow passengers to board and disembark trains, act as payment checkpoints, and facilitate transfers to other modes of transport.

Explanation: A rough grid pattern in a rapid transit network is beneficial because it provides a wide array of routes for passengers while maintaining reasonable speed and frequency of service.

Explanation: The primary purpose of Platform Screen Doors (PSDs) is to enhance passenger safety by creating a physical barrier that prevents people from falling onto the tracks.

Explanation: The primary purpose of rapid transit systems is to serve as a backbone for urban mobility by efficiently transporting large numbers of people over relatively short distances at high frequency.

Explanation: To address security concerns, some countries establish specialized transit police forces, and these security efforts are often integrated with revenue protection measures like checking for fare evasion.

Explanation: A common network configuration involves a central line that branches into multiple lines in the suburbs. This design allows for a higher frequency of service in the more densely populated central area.

Explanation: A primary function of rapid transit stations is to serve as crucial hubs that facilitate transfers between different modes of transport, such as buses or other train lines.

Explanation: High platforms are a common feature of rapid transit stations because they enable step-free access between the platform and the train, improving accessibility for all passengers.

Explanation: A fundamental characteristic of modern rapid transit systems is that they operate on an exclusive right-of-way, meaning their tracks are grade-separated and inaccessible to pedestrians or other vehicles.

Explanation: Most rapid transit systems differentiate their multiple routes using a combination of colors, names, and numbering to help passengers navigate the network.

Explanation: A typical rapid transit line can carry about 36,000 passengers per hour per direction, although some high-capacity systems in East Asia can carry significantly more.

Explanation: The topological design of rapid transit networks is shaped by factors like geography, travel patterns, costs, and politics. The color scheme of train cars is a branding element, not a factor in network design.

Explanation: Modern rapid transit systems leverage the internet and cell phones to offer passengers online maps, timetables, and real-time arrival information, often through standardized data formats for third-party applications.

Explanation: As of 2021, the New York City Subway is the largest single rapid transit service provider by number of stations (472), while the Shanghai Metro holds the record for the longest route length.

Explanation: As of 2021, China has the largest number of rapid transit systems in the world, totaling 40, and has been the global leader in metro expansion.

Explanation: The deepest metro system in the world is in St. Petersburg, Russia. While Kyiv's Arsenalna station is one of the deepest in the world, the overall system in St. Petersburg is deeper.

Explanation: The Singapore Mass Rapid Transit (MRT) system was the first in the world to provide full mobile phone reception in its underground stations and tunnels, a feature introduced in 1989.

Explanation: The deepest metro system in the world is located in St. Petersburg, Russia, where geological conditions necessitate that stations and tunnels are built at extreme depths, some as deep as 100-120 meters.

Explanation: As of 2021, the Shanghai Metro holds the record for the world's longest single-operator rapid transit system by route length.

Explanation: In the 21st century, China has become the world's leader in metro expansion, with almost 60 cities operating, constructing, or planning a rapid transit system as of 2021.

Explanation: Cities in the former Soviet Union, particularly Moscow, are renowned for their beautiful metro stations, which feature splendid decorations such as marble walls, polished granite floors, and mosaics.

Explanation: Due to geological conditions, some stations and tunnels in the St. Petersburg metro system lie as deep as 100–120 meters (330–390 feet) below the surface.

Explanation: Transportation planners estimate that a residential housing density of twelve dwelling units per acre, not five, is necessary to adequately support rapid rail services.

Explanation: Rapid transit systems have a lower environmental impact than extensive road transport systems and have been shown to lead to a massive reduction in CO2 emissions.

Explanation: The success and viability of mass transit systems depend on urban land-use planning, as they are not feasible in low-density communities that cannot provide sufficient ridership.

Explanation: Transportation planners estimate that a residential housing density of twelve dwelling units per acre is necessary to provide sufficient ridership to support rapid rail services.

Explanation: Rapid transit systems, particularly elevated or underground lines, allow for efficient transport without occupying expensive land, which fosters compact city development and avoids creating physical barriers.

Explanation: A key environmental benefit of rapid transit is its lower impact compared to road transport, including a massive reduction in CO2 emissions.

Explanation: Rapid transit systems involve high capital costs and carry a significant financial risk of cost overruns and benefit shortfalls, typically requiring public financing.