Rail tunnel

“ In cross-section, tunnel No. 1 is 13 ft. 7 ins. wide at formation level, increasing to 16 ft. 5 ins., with a total height of 18 ft. above rail-level, and a cross-sectional area of about 250 sq. ft. This large section will allow of small repairs being executed in the roof without interruption of the traffic, and will also allow of strengthening the walls by additional masonry on the inside. The thickness of the lining, never wholly absent, and the material of which it is composed, depend upon the pressure to be resisted, and only in the worst case is an invert resorted to. ”

“ The feasibility of combination rail-and-highway tunnels to eliminate the costs of snow removal or protection and to reduce grades over some western mountain passes, should be carefully investigated. It will be desirable to study at numerous points the possibilities of providing in a single structure, whether bridge or tunnel, for the crossing of rivers and other bodies of water by interregional routes and main railway lines. ”

“ The ballast for the permanent way was to be broken stone in the bottom, with gravel or hard slag for upper ballast. The rails and sleepers for the permanent way were to be furnished by the Early history of the undertaking—1879.Company, the road to be a cross-sleepered road with steel rails weighing 86 lbs. to the lineal yard of rail.
The original amount of the contract was very considerably increased, firstly, by the whole of the tunnel having an invert; secondly, by the brickwork lining being made 3 feet thick, instead of 2 feet 3 inches, over a considerable part of the length of the tunnel ”

“ New operating conditions, resulting from the application of electric traction to the movement of heavy railroad trains, which had been used initially in tunnels by the Baltimore and Ohio Railroad and was subsequently studied and adopted by railroads in Europe, made it possible to avoid the difficulty of ventilation connected with steam traction in tunnels, and permitted the use of grades practically prohibitive with the steam locomotive. The practicability of the tunnel extension project finally adopted was thus assured. ”

“ Instead of climbing far up and then coming down in long, slow curves, the train can run quickly straight through.
Tunnels are hard to dig. They often have to be blasted out of solid rock. So the builders don’t make them any bigger than they have to. Of course, there’s not room for a man to stand up on top of a freight car{61} as it goes through a tunnel. To protect brakemen who might forget, there is a device called a tell-tale close to the mouth of a tunnel. It is simply a fringe of cords hanging down from a tall bar across the track. ”

“ There are two important secondary techniques for opening subterranean and subaqueous ways, neither a method truly of tunneling. One of these, of ancient origin, used mainly in the construction of shallow subways and utility ways, is the “cut and cover” system, whereby an open trench is excavated and then roofed over. The result is, in effect, a tunnel. The concept of the other method was propounded in the early 19th century but only used practically in recent years. ”

“ It occasionally happens when filling-in is to take place in the future, or where landslides are liable to bury the tracks, that a railway tunnel has to be built on the surface of the ground. In such cases the construction of the tunnel consists simply in building the lining of the section on the ground surface with just enough excavation to secure the proper grade and foundation. Generally the lining [201] is finished on the outside with a waterproof coating, and is sometimes banked and partly covered with earth to protect the masonry from falling stones and similar shocks from other causes. ”

“ Trains coming through the tunnel from France were to emerge into the daylight and the ordinary open air of England either from a four-mile-long access tunnel connected to the South-Eastern's railway line at Abbots Cliff or—this was a favored alternative plan of Sir Edward's—at Shakespeare Cliff via a station to be constructed in a great square excavated a hundred and sixty feet deep in the ground, which would be covered over with glass, lighted by electric light, and equipped "with large waiting rooms and refreshment rooms." ”

“ Tunnels of great length are sometimes begun at several different parts by means of shafts sunk down to the required level, and each made to unite into one, but this depends upon where the earth is to be deposited; on railways it is common that the “level” is so chosen that the earth from tunnels and cuttings is always wanted to fill up hollows in their immediate vicinity (see “Railways”) , and when this is the case a series of “trucks” drawn by an engine on temporary tramways remove the earth from the tunnel as it progresses, to the next embankment, both works proceeding at the same time. ”

“ The character of the difficulties encountered in performing this duty will depend upon the depth at which the tunnel is driven. In constructing shallow tunnels by the cut-and-cover method care has to be taken first of all not to disturb the street traffic any more than is absolutely necessary. This condition precludes the single trench method of open cut tunneling in all places where the street traffic is at all dense, and compels the engineer to use the methods employed in Paris and New York, as previously described, or else the transverse trench or slice method employed in the Boston Subway. ”

“ To penetrate them by tunnels, except in very rare cases and short distances, is inexpedient; for the travelling steam-engine generally used on railroads cannot be used in a tunnel, owing to the air being rendered unfit for breathing by the effect of the fire. Besides the resistance that the air in the tunnel will give to the carriage passing through it, even were tunnels practicable, the great original expense of construction forms a strong objection. ”

“ We knew as a fact that, during the early construction of railways in England, our engineers resorted to tunnels to avoid gradients and curves (especially the former) that would almost be considered favourable at the present day. As experience increased and the power of the locomotive was developed, so did the amount of tunnel [371] work diminish. Hence it is that if the three estimates just stated be correct, the proportion of tunnel to railway on the 1st of January, 1856, was one mile to every 115; on 1st of January, 1863, one to every 144 miles; on 1st of January, 1867, one to every 154. ”

“ They never quite removed the machine from the heading when they were finished, but it was maintained right up to the outbreak of the Second World War, when it became derelict."
Adams and I walked back to the car. As we did so, he revealed himself as being pro-tunnel. "It's a tragic thing, this tunnel business, I think. If the tunnel had been built forty or fifty years ago, just think of what an asset to Europe it would have been," he said. We packed ourselves in, and Burgess drove us down a very rough, narrow road to the level of the railroad line. ”

“ Leaving the asylum grounds, the railway re-crosses the road by a hideous skew girder bridge of 180 feet span, supported by giant piers and retaining-walls, and then crosses the deep cutting of the South Eastern, to enter a cutting of its own leading into a tunnel a mile and a quarter in length—the new Merstham tunnel—running parallel with the old tunnel of the same name through which the South Eastern Railway passes. At the southern end of this gloomy tunnel is the pretty village of Merstham, where the hillside sinks down to the level lands between that point and Redhill. ”

“ Their Use in Reducing Grades—The Hoosac Tunnel—The Use Of Shafts—Tunnelling Under Water—The Detroit River Tunnel.
Sometimes the construction engineer of the railroad brings his new line face to face with a mountain too steep to be easily mounted. Then he may prepare to pierce it. Tunnels are not pleasant things through which to ride. They are, moreover, expensive to construct, and when once constructed are an unending care, necessitating expensive and constant inspection. ”

“ It is well known that about 35 years ago an attempt was made to construct a tunnel under the North River by using a "Pilot" system under compressed air and forming the tunnels in brick masonry. Owing to the very soft nature of the materials through which it passed, several serious accidents occurred, and the work was abandoned after about 2,000 ft. of tunnel had been constructed. Later, this work was taken up again, when a shield was installed and an additional 1,800 ft. ”

“ When a railway line is to be carried across a range of mountains or hills, the first question which arises is whether it is better to construct a tunnel or to make such a détour as will enable the obstruction to be passed with ordinary surface construction. The answer to this question depends upon the comparative cost of construction and maintenance, and upon the relative commercial and structural advantages and disadvantages of the two methods. In favor of the open road there are its smaller cost and the decreased time required in its construction. ”

“ This, Adams said, was to reinforce the tunnel at the point where it passed underneath the railway line. We went on again, this time walking on a dirt floor, and then we came to a timbered junction, from which the tunnel branched off again to the right in the north-east direction that was originally intended to bring it into line with the gallery at Shakespeare Cliff, while to the left there was a low-roofed chamber that probably once housed a siding and a maintenance workshop for the Beaumont boring machine. ”

“ It is hardly necessary to say that the great rival to the Mont Cenis or Summit Railway is the railway that is to be laid through the tunnel, which, in the official documents of both France and Italy is denominated “The Great Tunnel of the Alps.” But before we enter upon the description of this tunnel, an account of subterraneous construction from the earliest period we have been able to trace tunnels, may not be uninteresting.
Tunnelling through hills and mountains is not exactly “as old as the hills,” but the practice, nevertheless, is of great antiquity. ”

“ A couple of thousand armed men might easily come through the tunnel in a train at night, avoiding all suspicion by being dressed as ordinary passengers, and the first thing we should know of it would be by finding the fort at our end of the tunnel, together with its telegraph office, and all the electrical arrangements, wires, batteries, etc., intended for the destruction of the tunnel, in the hands of an enemy. We know that ... trains could be safely sent through the tunnel every five minutes, and do the entire distance from the station at Calais to that at Dover in less than half an hour. ”

“ Still it remains, to the infinite credit of a national persistence, that there is no record in the annals of American engineering where the workers have finally given up a tunnel job. Lives have been sacrificed, good-sized fortunes swept away, but in the end the resistless railroad has always found its underground path.
The tunnel-workers can tell you of the accident when the subway was being driven under the East River from Manhattan to Brooklyn, three years ago. ”

“ Two steam locomotives which were being stored at Weehawken (part of the plant from another contract) , were used for hauling the cars in place of the electric ones used with the 2-ft. gauge railway.
Tunnel Transport.—The track used in the tunnel was of 2-ft. gauge, laid with the 20-lb. rails previously used in driving the iron-lined tunnels. The mining cars (previously mentioned in describing the driving of the iron-lined tunnels) were used for transporting the invert concrete, although, for most of the work, dumping buckets carried on flat cars were used. ”

“ It was possible in the model series, without neglecting any major advancement in the art of rock tunneling, to complete the sequence of development with only a single additional model. Many of the greatest works of civil engineering have been those concerned directly with transport, and hence are the product of the present era, beginning in the early 19th century. The development of the ancient arts of route location, bridge construction, and tunnel driving received a powerful stimulation after 1800 under the impetus of the modern canal, highway, and, especially, the railroad. ”

“ For a good many years New York and Baltimore, in particular, have been pierced with these sub-surface railroads; it is a construction feature that increases as our great cities themselves increase. No river is to-day too formidable to be conquered by these underground traffic routes. A river such as the Hudson or the Detroit may sometimes halt the bridge-builders; it has but slight terror for the tunnel engineers.
The tunnel-work is apt to be a separate part of the [Pg 50] work of building a railroad. It calls for its own talent, and that of an exceedingly expert sort. ”

“ Occasionally favourable opportunities present themselves for making horizontal shafts. For a portion of its length the tunnel may be located at no very great distance from the precipitous sides of some deep mountain ravine, or run near to the cliffs on the sea-coast, and advantage can be taken to drive a lateral heading or gallery through which the material from the tunnel excavation may be conveyed and thrown out into the gorge or seashore below. ”