Metro Train Ppt 1r117

METR O TRAIN S (under

INTRODUCTION 

A metro system underground tunnel is an electric enger railway in an urban area with a high capacity and frequency, and separation from other traffic. Rapid transit systems are typically located either in underground tunnels or on elevated rails above street level. But here only metro train (underground tunnels) have been discussed.

Continue… Underground tunnels fall under traffic tunnels (all tunnels which are excavated to divert the traffic load).  Rapid transit evolved from steam railways during the late 19th century and now a days it has become a necessity for the larger cities all over the world.  Rapid transit of India consists of “metros” (both elevated and underground) and it started in1984(Kolkata Metro). 

Continue… Rapid transit has been in use in all major cities of India (Kolkata, New Delhi, etc.) and some are under construction (Jaipur, Chennai, etc.) or in planning (Kanpur, Patna, etc.).  The underground tunnel metro trains are very helpful for rapid transit of any country because these reduce the congestion in transportation system. But it (tunnelling) has been one of the most challenging jobs for engineers. 

METRO UNDERGROUND TUNNELS Underground 

tunnels are the underground route or age driven through the ground without disturbing the overlying soil or rock cover.

TERMINOL OGY

Excavation in multiple drifts

Transportation tunnel cross-sections

Top heading

Core (strozze)

Springline

Bench

Bottom

Invert

Circular

Wall

Crown

Horseshoe

Vertical walls arch roof

TERMINOLOGY Crown: The uppermost part of the tunnel,  Drift : A horizontal excavation ,  Heading : The excavated face of the tunnel,  Invert : The bottom (floor) of the tunnel,  Wall : The side of the tunnel,  Portal : The tunnel entrance,  Springline : The line at which the tunnel wall breaks from sloping outward to sloping inward toward the crown. 

MACHINE USED FOR EXCAVATING TUNNELS

TUNNEL BORING MACHINE

Continue… 

TBM(Tunnel boring machine) is usually used in rail transportation system for excavation.

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Underground tunnels move traffic away from street level, leaving more land available for buildings and other uses. In areas of high land prices and dense land use, tunnels may be the only economic route for the fast transportation.

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Excavation of underground tunnels is a very difficult job. It requires sound knowledge of rocks and soil.

METHODS OF TUNNELLING 

Following are some of the methods used for tunnelling:1. Cut and cover 2. Drill and blast, 3. Bored, 4. Sequential excavation, etc. But bored tunnelling is the most common method which is used for excavation in “METRO”.

Continue… Bored tunnelling is done mainly by using TBM (tunnel boring machine) in rail transportation system.  It can also be done by using high intensive LASER light.  The choice of tunnelling method may be dictated by geological and hydrological conditions, cross-section and length of continuous tunnel,local experience and time/cost considerations (what is the value of time in the project), limits of surface disturbance, and many others factors. 

NECESSITY…. 

India being an overpopulated and a developing country, needed a much faster and easy public transportation which could easily fulfill the need of fast and busy lives of people. The rapid transit system (metro) can fulfill these needs. Also underground tunnels can be very useful for saving land that can be used for other purposes example construction of houses etc. Hence a need for superfast metro trains emerged largely in cities of India…

MERITS………….. Reduce congestion problems in transportation,  Saving time,  Economical for the people,  Produce less pollution in environment,  Transportation become very fast & secure,  It saves land for building construction & other purposes, etc. 

DEMERITS………… 

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During tunnel construction whole transportation system of the city is disturbed. Need of skilled labour. The capital cost is high. Potential environmental impacts in of noise, dust and visual on sensitive receives and the areas located near the tunnel portal. Tunnelling involves the use of heavy machines which causes high risk to mankind and property…

HAZARDS 

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Owing to the enclosed space of a tunnel, fires can have very serious effects on s. The main dangers are gas and smoke production, with low concentrations of carbon monoxide being highly toxic. Fires killed 11 people in the Gotthard tunnel fire of 2001 for example, all of the victims succumbing to smoke and gas inhalation. Over 400 engers died in the Balvano train disaster in Italy in 1944, when the locomotive halted in a long tunnel, etc…

SAFETY & SECURITY 

Rapid transits are a public space, and may suffer from security problems: petty crimes such as pick pocketing and baggage theft, and more serious crimes such as violence. Security measures include video surveillance, security guards and conductors.

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Rapid transits have been subject to terrorism with many casualties, such as The 1995 Tokyo subway sarin gas attack.

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Compared to other modes of transport, rapid transit has a good safety record, with few accidents. Rail transport is subject to strict safety regulations, with requirements for procedure and maintenance to minimize risk.

TUNNEL V/S BRIDGE 

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Tunnels are always preferred over bridge (if possible). Since tunnel is generally more costly to construct than a bridge. But bridges usually require a larger footprint on each shore than tunnels. There are actually more codes to follow with bridges than with tunnels. Other reasons for choosing a tunnel instead of a bridge include avoiding difficulties with tides, weather and shipping during construction, aesthetic reasons (preserving the above-ground view, landscape, and scenery), and also for weight capacity reasons (it may be more feasible to build a tunnel than a sufficiently strong bridge). Etc……

QUERIES ? ??

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