Bremen is a commercial city in north Germany. Population of the city is approximately 600,000 although the metropolitan area population is more than 2.37 million. Bremen depends upon public transport for a high proportion of daily journeys, particularly on the ubiquitous streetcar system. The streetcars penetrate all areas of the central city with a major plaza at the railway station. Streetcars also directly serve the terminal
building at the airport. The streetcars are supplemented
by a system of buses and by regional railways. A  comprehensive integrated tariff union has been developed so that the same tickets are used on all modes of transport.