Give a brief summary of the text below: The Urban Transit Challenge
As cities continue to become more dispersed, the cost of building and operating public transportation systems increases. For instance, only about 80 large urban agglomerations have a subway system, the great majority of them being in developed countries. Furthermore, dispersed residential patterns, characteristic of automobile dependent cities, makes public transportation systems less convenient for the average commuter.
In many cities additional investments in public transit did not result in significant additional ridership. Unplanned and uncoordinated land development hasled to rapid expansion of the urban periphery. Residents may become isolated in outlying areas without access to affordable and convenient public transportation. Urban transit is often perceived as the most efficient transportation mode for urban areas, notably large cities. However, surveys reveal stagnation or a decline of public transit systems, especially in North America. The economic relevance of public transit is being questioned. This paradox is partially explained by the spatial structure of contemporary cities which are oriented along servicing the needs of the individual, not necessarily the needs of the collectivity. Thus, the automobile remains the preferred mode of urban transportation. In addition, public transit is publicly owned, implying that it is a politically motivated service that provides limited economic returns. In Europe transit systems also depend on government subsidies. Little or no competition is permitted as wages and fares regulated, undermining any price of adjustments to changes in ridership. Thus, public transit often serves the purpose of a social function («public service») as it provides accessibility and social equity, but with limited relationships with economic activities.
