Railway Bridge And Tunnel Engineering Pdf
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PDF download is possible from official site but you can download the istudy mobile app for syllabus on mobile. The syllabus PDFs can be downloaded from official website. The detail syllabus for railways, bridges and tunnels is as follows.
- RAILWAY, BRIDGE AND TUNNEL ENGINEERING
- Railway, Bridge and Tunnel Engineering
- TRANSPORTATION ENGINEERING STUDY MATERIAL FOR RRB JE BY CIVILENGGFORALL FREE DOWNLOAD PDF
Dalal K. The subject-matter is characterized by comprehension as well as methodical and easy-to-follow style. The Section I: Railway Engineering is well divided in to Thirteen chapters including Introduction; Railway track gauges; Surveys and alignment of railway lines; Railway traction; Rails; Sleepers; Ballast; Track fittings; Geometric design of a track; Resistance to traction; Points and crossings; Railway stations and yards; Signalling and interlocking; etc.
RAILWAY, BRIDGE AND TUNNEL ENGINEERING
A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods. A tunnel may be for foot or vehicular road traffic , for rail traffic, or for a canal. The central portions of a rapid transit network are usually in the tunnel. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers.
Utility tunnels are used for routing steam, chilled water, electrical power or telecommunication cables, as well as connecting buildings for convenient passage of people and equipment. Secret tunnels are built for military purposes, or by civilians for smuggling of weapons , contraband , or people.
Special tunnels, such as wildlife crossings , are built to allow wildlife to cross human-made barriers safely. Tunnels can be connected together in tunnel networks. A tunnel is relatively long and narrow; the length is often much greater than twice the diameter , although similar shorter excavations can be constructed, such as cross passages between tunnels. The definition of what constitutes a tunnel can vary widely from source to source. In the UK, a pedestrian, cycle or animal tunnel beneath a road or railway is called a subway , while an underground railway system is differently named in different cities, the " Underground " or the " Tube " in London , the " Subway " in Glasgow , and the " Metro " in Newcastle.
The place where a road, railway, canal or watercourse passes under a footpath, cycleway, or another road or railway is most commonly called a bridge or, if passing under a canal, an aqueduct. Where it is important to stress that it is passing underneath, it may be called an underpass , though the official term when passing under a railway is an underbridge. A longer underpass containing a road, canal or railway is normally called a "tunnel", whether or not it passes under another item of infrastructure.
An underpass of any length under a river is also usually called a "tunnel", whatever mode of transport it is for. In the US, the term "subway" means an underground rapid transit system, and the term pedestrian underpass is used for a passage beneath a barrier. Rail station platforms may be connected by pedestrian tunnels or footbridges. Much of the early technology of tunneling evolved from mining and military engineering. The etymology of the terms "mining" for mineral extraction or for siege attacks , "military engineering", and " civil engineering " reveals these deep historic connections.
Predecessors of modern tunnels were adits to transport water for irrigation or drinking, and sewerage. The first Qanats are known from before B. It is the second known tunnel to have been excavated from both ends, after the Siloam tunnel in the neighbourhood of Silwan in eastern Jerusalem. In Ethiopia , the Siqurto foot tunnel , hand-hewn in the middle ages, crosses a mountain ridge.
A major tunnel project must start with a comprehensive investigation of ground conditions by collecting samples from boreholes and by other geophysical techniques. An informed choice can then be made of machinery and methods for excavation and ground support, which will reduce the risk of encountering unforeseen ground conditions. In planning the route, the horizontal and vertical alignments can be selected to make use of the best ground and water conditions.
It is common practice to locate a tunnel deeper than otherwise would be required, in order to excavate through solid rock or other material that is easier to support during construction. Conventional desk and preliminary site studies may yield insufficient information to assess such factors as the blocky nature of rocks, the exact location of fault zones, or the stand-up times of softer ground.
This may be a particular concern in large-diameter tunnels. To give more information, a pilot tunnel or "drift tunnel" may be driven ahead of the main excavation. This smaller tunnel is less likely to collapse catastrophically should unexpected conditions be met, and it can be incorporated into the final tunnel or used as a backup or emergency escape passage.
Alternatively, horizontal boreholes may sometimes be drilled ahead of the advancing tunnel face. For water crossings, a tunnel is generally more costly to construct than a bridge. However, navigational considerations may limit the use of high bridges or drawbridge spans intersecting with shipping channels, necessitating a tunnel. Bridges usually require a larger footprint on each shore than tunnels. In areas with expensive real estate, such as Manhattan and urban Hong Kong , this is a strong factor in favor of a tunnel.
Boston's Big Dig project replaced elevated roadways with a tunnel system to increase traffic capacity, hide traffic, reclaim land, redecorate, and reunite the city with the waterfront. The Queensway Tunnel under the River Mersey at Liverpool was chosen over a massively high bridge for defense reasons; it was feared that aircraft could destroy a bridge in times of war.
Maintenance costs of a massive bridge to allow the world's largest ships to navigate under were considered higher than for a tunnel. Similar conclusions were reached for the Kingsway Tunnel under the Mersey. In Hampton Roads, Virginia , tunnels were chosen over bridges for strategic considerations; in the event of damage, bridges might prevent US Navy vessels from leaving Naval Station Norfolk.
Other reasons for choosing a tunnel instead of a bridge include avoiding difficulties with tides, weather, and shipping during construction as in the Some water crossings are a mixture of bridges and tunnels, such as the Denmark to Sweden link and the Chesapeake Bay Bridge-Tunnel in Virginia. There are particular hazards with tunnels, especially from vehicle fires when combustion gases can asphyxiate users, as happened at the Gotthard Road Tunnel in Switzerland in One of the worst railway disasters ever, the Balvano train disaster , was caused by a train stalling in the Armi tunnel in Italy in , killing passengers.
Designers try to reduce these risks by installing emergency ventilation systems or isolated emergency escape tunnels parallel to the main passage. Government funds are often required for the creation of tunnels.
Civil engineers usually use project management techniques for developing a major structure. Understanding the amount of time the project requires, and the amount of labor and materials needed is a crucial part of project planning.
Also, the land needed for excavation and construction staging, and the proper machinery must be selected. Large infrastructure projects require millions or even billions of dollars, involving long-term financing, usually through issuance of bonds. The costs and benefits for an infrastructure such as a tunnel must be identified.
However, the Port Authority of New York and New Jersey was not aware of this bill and had not asked for a grant for such a project. Tunnels are dug in types of materials varying from soft clay to hard rock.
The method of tunnel construction depends on such factors as the ground conditions, the groundwater conditions, the length and diameter of the tunnel drive, the depth of the tunnel, the logistics of supporting the tunnel excavation, the final use and the shape of the tunnel and appropriate risk management.
There are three basic types of tunnel construction in common use. Cut-and-cover tunnels are constructed in a shallow trench and then covered over.
Bored tunnels are constructed in situ, without removing the ground above. Finally, a tube can be sunk into a body of water, which is called an immersed tunnel. Cut-and-cover is a simple method of construction for shallow tunnels where a trench is excavated and roofed over with an overhead support system strong enough to carry the load of what is to be built above the tunnel.
Shallow tunnels are often of the cut-and-cover type if under water, of the immersed-tube type , while deep tunnels are excavated, often using a tunnelling shield. For intermediate levels, both methods are possible. Large cut-and-cover boxes are often used for underground metro stations, such as Canary Wharf tube station in London.
This construction form generally has two levels, which allows economical arrangements for ticket hall, station platforms, passenger access and emergency egress, ventilation and smoke control, staff rooms, and equipment rooms. The interior of Canary Wharf station has been likened to an underground cathedral, owing to the sheer size of the excavation. This contrasts with many traditional stations on London Underground , where bored tunnels were used for stations and passenger access.
Nevertheless, the original parts of the London Underground network, the Metropolitan and District Railways, were constructed using cut-and-cover. These lines pre-dated electric traction and the proximity to the surface was useful to ventilate the inevitable smoke and steam. A major disadvantage of cut-and-cover is the widespread disruption generated at the surface level during construction. This, and the availability of electric traction, brought about London Underground's switch to bored tunnels at a deeper level towards the end of the 19th century.
Tunnel boring machines TBMs and associated back-up systems are used to highly automate the entire tunnelling process, reducing tunnelling costs. In certain predominantly urban applications, tunnel boring is viewed as a quick and cost-effective alternative to laying surface rails and roads. Expensive compulsory purchase of buildings and land, with potentially lengthy planning inquiries, is eliminated.
Disadvantages of TBMs arise from their usually large size — the difficulty of transporting the large TBM to the site of tunnel construction, or alternatively the high cost of assembling the TBM on-site, often within the confines of the tunnel being constructed.
There are a variety of TBM designs that can operate in a variety of conditions, from hard rock to soft water-bearing ground. Some types of TBMs, the bentonite slurry, and earth-pressure balance machines have pressurized compartments at the front end, allowing them to be used in difficult conditions below the water table. This pressurizes the ground ahead of the TBM cutter head to balance the water pressure. The operators work in normal air pressure behind the pressurized compartment, but may occasionally have to enter that compartment to renew or repair the cutters.
This requires special precautions, such as local ground treatment or halting the TBM at a position free from water. The borehole has a diameter of 8. All of these machines were built at least partly by Herrenknecht. Clay-kicking is a specialized method developed in the United Kingdom of digging tunnels in strong clay-based soil structures.
Unlike previous manual methods of using mattocks which relied on the soil structure to be hard, clay-kicking was relatively silent and hence did not harm soft clay-based structures. The clay-kicker lies on a plank at a degree angle away from the working face and inserts a tool with a cup-like rounded end with the feet.
Turning the tool manually, the kicker extracts a section of soil, which is then placed on the waste extract. Used in Victorian civil engineering, the method found favor in the renewal of Britain's ancient sewerage systems, by not having to remove all property or infrastructure to create a small tunnel system.
The method was virtually silent and so not susceptible to listening methods of detection. A temporary access shaft is sometimes necessary during the excavation of a tunnel. They are usually circular and go straight down until they reach the level at which the tunnel is going to be built.
A shaft normally has concrete walls and is usually built to be permanent. Once the access shafts are complete, TBMs are lowered to the bottom and excavation can start. Shafts are the main entrance in and out of the tunnel until the project is completed. If a tunnel is going to be long, multiple shafts at various locations may be bored so that entrance to the tunnel is closer to the unexcavated area. Once construction is complete, construction access shafts are often used as ventilation shafts , and may also be used as emergency exits.
The main idea of this method is to use the geological stress of the surrounding rock mass to stabilize the tunnel, by allowing a measured relaxation and stress reassignment into the surrounding rock to prevent full loads becoming imposed on the supports.
Based on geotechnical measurements, an optimal cross section is computed. The excavation is protected by a layer of sprayed concrete, commonly referred to as shotcrete.
Other support measures can include steel arches, rock bolts, and mesh. Technological developments in sprayed concrete technology have resulted in steel and polypropylene fibers being added to the concrete mix to improve lining strength.
Railway, Bridge and Tunnel Engineering
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TRANSPORTATION ENGINEERING STUDY MATERIAL FOR RRB JE BY CIVILENGGFORALL FREE DOWNLOAD PDF
A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods. A tunnel may be for foot or vehicular road traffic , for rail traffic, or for a canal. The central portions of a rapid transit network are usually in the tunnel.
By Ketki Rangwala Dalal. It should also prove great of interest and practical use to the practicing professionals. Types of sleepers engineering Requirements of an ideal material for sleeper
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