how subways work

by:Gewinn     2019-08-31
The New York City subway system is undergoing a massive overhaul.
The planned addition is a new tunnel that extends from Long Island to Manhattan. A tunnel-Boring machine (TBM)
Will do a lot of digging.
The full rock tunnel boring machine is a large machine that usually needs to be transported in sections.
It uses discs and forklifts to crush and remove rocks and debris, forming a tunnel.
The conveyor belt removes the debris from the tunnel so that the staff can handle it.
Although it moves slowly, the TBM can pass through the hard bedrock and softer soil and support the tunnel when digging.
But a machine like this does not exist in the process of building the world\'s first subway.
Construction workers had to tap the subway lines of cities like London and Paris by hand.
It\'s a slow, hard, dangerous job.
For example, it takes nearly 8,000 workers to dig New York City subway tunnels.
Thousands of people were injured during construction and more than 60 people were killed.
The improved construction method does not completely prevent the occurrence of subway construction accidents.
On January 2007, a construction site in Sao Paulo, Brazil collapsed, burying a minibus and several dump trucks, causing 260 vehicles. foot-wide crater.
Over the years, the staff have used various methods to excavate subway tunnels.
Some people blow rocks with explosives, others use movable shields to protect excavators when digging hollow pipes under streets and buildings.
In the 1950 s, some crew members began using the new Austrian tunnel method (NATM)
, A collection of techniques used to determine how and where to mine.
You can learn more about other modern tunnel engineering methods in tunnel engineering.
The most common one
The common method of early subway construction isand-cover method.
This method requires the worker to do it as suggested by the name ---
Dig a deep ditch and cover it.
In order to carry out stable coverage at the excavation site, the workers pile on both sides of the ditch.
They then used piles as support to pass the truss and beam through the ditch.
Temporary or permanent roadway can be parked on this surface.
Beams and truss can also maintain suspension support for pipes and pipelines unearthed during tunnel excavation.
With this approach, the staff can usually create a tunnel deep enough for the train to pass through, but shallow enough to avoid hitting a rock bed that is almost non-penetrating.
This method is safer and more practical than horizontal excavation underground.
However, staff often use city streets as a guide to excavation sites, resulting in complete but temporary destruction of existing roads.
Planners are willing to accept this inconvenience as road-oriented will make it easier to tunnel construction.
First of all, it allows planners to make sure the subway gets to where people need it.
Second, it reduces the possibility of encountering a building foundation or otherwise damaging an existing structure.
However, walking along this road does not always prevent staff from encountering unexpected obstacles.
We will take a look at some of them in the next section.
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