1) The quickest means of city's transport is typically the Underground or subway system.
2) It is necessary to construct Underground railways in large cities to alleviate traffic congestion, provide fast and efficient transportation for residents, and reduce pollution.
3) The construction of underground railway systems is very expensive and complicated due to the need for tunneling underground, dealing with existing infrastructure, such as utilities and buildings, and ensuring safety and stability of the underground structures.
4) The permanent way of underground railroads differs from ground-based railway tracks in terms of construction materials and methods. Underground railways often use concrete or steel tracks laid on a solid bed, while ground-based railway tracks typically use wooden or concrete sleepers with ballast.
5) There is no ballast on underground railways because the tracks are typically laid on a solid bed of concrete or rock to provide stability and reduce maintenance needs.
6) Metro trains are powered by electricity, not steam.
7) The current for Metro trains is obtained from an overhead catenary system or a third rail.
8) The Underground carrying capacity depends on factors such as the number of trains running, the frequency of service, the length of platforms, and the design of the train cars.
9) Many cities around the world have already built Underground railways, including London, New York City, Paris, Tokyo, Moscow, and many others.
10) The first underground railway line was laid down in London, United Kingdom.
11) The city with the largest subway system in the world is Tokyo, Japan.
12) The length of the metro line in Istanbul is approximately 165 kilometers.