clip_image002By reading the word ‘subway’, one might think about famous “Subway” restaurant chain. But this isn’t the topic of I am going to talk about in this article ahead. So, jokes apart, I am talking about the ‘Subway Tunnel’. How did the idea to build tunnels or subways below the surface of the earth come? Basically, Subways & tunnels are meaningfully one and the same. In subways, tunnels are built.
Subways means ‘Submerged Ways’, that’s what I think and are an alternative means of transportation which are used by people and is located below the ground surface. Hence comes the name – Submerged ways or popularly “SUB-WAYS”. Construction of ‘subways’ is difficult job for civil engineers because one can’t see what is beyond the tunnel. In many of the world’s major cities, it would be difficult to imagine life without a subway. In some areas, it seems like the subway is everywhere you look, even though you can’t see its tunnels from the street.
Roadways and intersections in many major cities became congested and dangerous and travel from place to place grew increasingly difficult. Subways came into existence for the same basic reason: Large numbers of people were moving to the cities, and the roads couldn’t carry them all.
Civil engineers eventually came to the conclusion that they’d now have to build a new system of transportation to keep the city running. Since there was no space above ground, the only option was to put this system under the city.
The world’s oldest subway, the London Underground, opened in January 1863. Subways can be used for railways or may be used for roadways. So, nowadays subways exist in every Metropolitan city.
Subway construction can use two different methods: “cut and cover” and “deep bore”. Deep bore method is commonly used as it uses ‘Boring Machines’ which generally can excavate only in one fixed shape and is generally circular.
The main advantage of subways is that to reduce the distance between two places and to distribute the traffic uniformly. As in this 21st century, time is money. And everyone wants to move fast in daily life. So, subways are preferred. No extra traffic is there inside tunnels other than the trains or road users so there is fast transportation possible.
And the disadvantage or say drawback of subways is the suffocation inside the tunnel due to more population. To overcome this, electrical power is used which controls the subway’s ventilation system.
A common difficulty in building subways involves ‘Underground water’. If it exists, it is to be removed out and then construction is carried on further. In addition to underground water, many subways have to cross rivers and other aboveground bodies of water. So, difficulty may arise because one can’t construct tunnel beyond river or lake. The water of river or sea may percolate inside and affect the workers. So, bridges are built to overcome the difficulty.

After digging subway tunnels, the main objective was to keep them waterproof by applying waterproof material coated in concrete and lining the tunnel with asphalt and brick. Modern subway crews often use materials like Shotcrete, or sprayable concrete, to finish tunnel walls. Many tunnels, particularly those that house subway stations, also have a decorative layer of tile or stone. Tile is also a good reflective surface so, it is used roadway tunnels, which makes safer driving conditions and uses less artificial lighting. Scattered fluorescent lights, as well as the cars headlights, reflect light off the walls, illuminating all areas of the tunnel. So, tiles are used as outer layer of tunnels.
Subways are now an important part of any major city’s map and are indeed a masterpiece of a Civil Engineer’s creativity!

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