ITS CONSTRUCTION, DEVELOPMENT,
MANAGEMENT, AND APPLIANCES
BY
THOMAS CURTIS CLARKETHEODORE VOORHEES
JOHN BOGARTBENJAMIN NORTON
M. N. FORNEYARTHUR T. HADLEY
E. P. ALEXANDERTHOMAS L. JAMES
H. G. PROUTCHARLES FRANCIS ADAMS
HORACE PORTERB. B. ADAMS, JR.
WITH AN INTRODUCTION BY
THOMAS M. COOLEY
CHAIRMAN OF INTERSTATE COMMERCE COMMISSION
THE LAST SPAN—READY TO JOIN.
By THOMAS M. COOLEY.
The railroads of the United States, now aggregating a hundred and fifty thousand miles and having several hundred different managements, are frequently spoken of comprehensively as the railroad system of the country, as though they constituted a unity in fact, and might be regarded and dealt with as an entirety, by their patrons and by the public authorities, whenever the conveniences they are expected to supply, or the conduct of managers and agents, come in question. So far, however, is this from being the case, that it would be impossible to name any other industrial interest where the diversities are so obvious and the want of unity so conspicuous and so important. The diversities date from the very origin of the roads; they have not come into existence under the same laws nor subject to the same control. It was accepted as an undoubted truth in constitutional law from the first that the authority for the construction of railroads within a State must come from the State itself, which alone could empower the promoters to appropriate lands by adversary proceedings for the purpose. The grant of corporate power must also come from the State, or, at least, have State recognition and sanction; and where the proposed road was to cross a State boundary, the necessary corporate authority must be given by every State through or into which the road was to run. It was conceded that the delegated powers of the General Government did not comprehend the granting of charters for the construction of these roads within the States, and even in the Territories charters were granted by the local legislatures. The case of the transcontinental roads was clearly exceptional; they were to be constructed in large part over the public domain, and subsidies were to be granted by Congress for the purpose. They were also, in part at least, to be constructed for governmental reasons as national agencies; and invoking State authority for the purpose seemed to be as inconsistent as it would be inadequate. But, though these were exceptional cases, the magnitude and importance of the Pacific roads are so immense that the agency of the General Government in making provision for this method of transportation must always have prominence in railroad history and railroad statistics.
Not only have the roads been diverse in origin, but the corporations which have constructed them have differed very greatly in respect to their powers and rights, and also to the obligations imposed by law upon them. The early grants of power were charter-contracts, freely given, with very liberal provisions; the public being more anxious that they be accepted and acted upon than distrustful of their abuse afterward. Many of them were not subject to alteration or repeal, except with the consent of the corporators; and some of them contained provisions intended to exclude or limit competition, so that, within a limited territory, something in the nature of a monopoly in transportation would be created. The later grants give evidence of popular apprehension of corporate abuses; the legislature reserves a control over them, and the right to multiply railroads indefinitely is made as free as possible, under the supposition that in this multiplication is to be found the best protection against any one of them abusing its powers. In very many cases the motive to the building of a new road has been antagonism to one already in existence, and municipalities have voted subsidies to the one in the hope that, when constructed, it would draw business away from the other. The anomaly has thus been witnessed of distrust of corporate power being the motive for increasing it; and the multiplication of roads has gone on, without any general supervision or any previous determination by competent public authority that they were needed, until the increase has quite outrun in some sections any proper demand for their facilities.
Roads thus brought into existence, without system and under diverse managements, it was soon seen were capable of being so operated that the antagonism of managers, instead of finding expression in legitimate competition, would be given to the sort of strife that can only be properly characterized by calling it, as it commonly is called, a war. From such a war the public inevitably suffers. The best service upon the roads is only performed when they are operated as if they constituted in fact parts of one harmonious system; the rates being made by agreement, and traffic exchanged with as little disturbance as possible, and without abrupt break at the terminals. But when every management might act independently, it sometimes happened that a company made its method of doing business an impediment instead of a help to the business done over other roads, recognizing no public duty which should preclude its doing so, provided a gain to itself, however indirect or illegitimate, was probable. Many consolidations of roads have had for their motive the getting rid of this power to do mischief on the part of roads absorbed.
In nothing is the want of unity so distinctly and mischievously obvious as in the power of each corporation to make rates independently. It may not only make its own local rates at discretion, but it may join or refuse to join with others in making through rates; so that an inconsiderable and otherwise insignificant road may be capable of being so used as to throw rates for a large section of the country into confusion, and to render the making of profit by other roads impossible. It is frequently said in railroad circles that roads are sometimes constructed for no other reason than because, through this power of mischief, it will be possible to levy contributions upon others, or to compel others, in self-protection, to buy them up at extravagant prices. Cases are named in which this sort of scheming is supposed to have succeeded, and others in which it is now being tried.
Evils springing from the diversities mentioned have been cured, or greatly mitigated, by such devices as the formation of fast-freight lines to operate over many roads; by allowing express companies to come upon the roads with semi-independence in the transportation of articles, where, for special reasons, the public is content to pay an extra price for extra care or speed; and by arrangements with sleeping-car companies for special accommodations in luxurious cars to those desiring them. These collateral arrangements, however, have not been wholly beneficial; and had all the roads been constructed as parts of one system and under one management, some of them would neither have been necessary nor defensible. They exist now, however, with more or less reason for their existence; and they tend to increase the diversities in railroad work.
The want of unity which has been pointed out tended to breed abuses specially injurious to the public, and governmental regulation was entered upon for their correction. Naturally the first attempts in this direction were made by separate States, each undertaking to regulate for itself the transportation within its own limits. Such regulation would have been perfectly logical, and perhaps effectual, had the roads within each State formed a system by themselves; but when State boundaries had very little importance, either to the roads themselves or to the traffic done over them, unless made important by restrictive and obstructive legislation, the regulation by any State must necessarily be fragmentary and imperfect, and diverse regulation in different States might be harmful rather than beneficial. It must be said for State regulation that it has in general been exercised in a prudent and conservative way, but it is liable to be influenced by a sensitive and excitable public opinion; and as nothing is more common than to find gross abuses in the matter of railroad transportation selfishly defended in localities, and even in considerable sections, which are supposed to receive benefits from them, it would not be strange if the like selfishness should sometimes succeed in influencing the exercise of power by one State in a manner that a neighboring State would regard as unfriendly and injurious.
The Federal Government recently undertook the work of regulation, and in doing so accepted the view upon which the States had acted, and so worded its statute that the transportation which does not cross State lines is supposed to be excluded. The United States thus undertakes to regulate interstate commerce by rail, and the States regulate, or may regulate, that which is not interstate. It was perhaps overlooked at first that, inasmuch as Government control may embrace the making of classifications, prescribing safety and other appliances, and naming rates, any considerable regulation of State traffic and interstate traffic separately must necessarily to some extent cause interference. The two classes of traffic flow on together over the same lines in the same vehicles under the management of the same agencies, with little or no distinction based on State lines; the rates and the management influenced by considerations which necessarily are of general force, so that separate regulation may without much extravagance be compared to an attempt in the case of one of our great rivers to regulate the flow of the waters in general, but without, in doing so, interfering with an independent regulation of such portion thereof as may have come from the springs and streams of some particular section. This is one of many reasons for looking upon all existing legislation as merely tentative.
No doubt the time will come when the railroads of the country will constitute, as they do not now, a system. There are those who think this may, sufficiently for practical purposes, be accomplished by the legalization of some scheme of pooling; but this is a crude device, against which there is an existing prejudice not easily to be removed. Others look for unity through gradual consolidations, the tendency to which is manifest, or through something in the nature of a trust, or by means of more comprehensive and stringent national control. Beyond all these is not infrequently suggested a Government ownership.
Of the theories that might be advanced in this direction, or the arguments in their support, nothing further will be said here; the immediate purpose being accomplished when it is shown how misleading may be the term system, when applied to the railroads of the country as an aggregate, as now owned, managed, and controlled.
Every man in the land is interested daily and constantly in railroads and the transportation of persons and property over them. The price of whatever he eats, or wears, or uses, the cost and comfort of travel, the speed and convenience with which he shall receive his mail and the current intelligence of the day, and even the intimacy and extent of his social relations, are all largely affected thereby. The business employs great numbers of persons, and the wages paid them affect largely the wages paid in other lines of occupation. The management of the business in some of its departments is attended by serious dangers, and thousands annually lose their lives in the service. Other thousands annually are either killed or injured in being transported; the aggregate being somewhat startling, though unquestionably this method of travel is safer than any other. The ingenuity which has been expended in devices to make the transportation rapid, cheap, and safe may well be characterized as marvellous, and some feats in railroad engineering are the wonder of the world. With all these facts and many others to create a public interest in the general subject, the editor of Scribner's Magazine, some little time ago, applied to writers of well-known ability and competency to prepare papers for publication therein upon the various topics of principal interest in the life and use of railroads, beginning with the construction, and embracing the salient facts of management and service. He was successful in securing a series of papers of high value, the appearance of which has been welcomed from month to month, beginning with June, 1888, with constant and increasing interest. These papers have a permanent value; and, in obedience to a demand for their separate publication in convenient form for frequent reference, the publishers now reproduce them with expansions and additions. A reference to the several titles will convince anyone at all familiar with the general subject that the particular topic is treated in every instance by an expert, entitled as such to speak with authority.
By THOMAS CURTIS CLARKE.
Roman Tramways of Stone—First Use of Iron Rails—The Modern Railway created by Stephenson's "Rocket" in 1830—Early American Locomotives—Key to the Evolution of the American Railway—Invention of the Swivelling Truck, Equalizing Beams, and the Switchback—Locating a Road—Work of the Surveying Party—Making the Road-bed—How Tunnels are Avoided—More than Three Thousand Bridges in the United States—Old Wooden Structures—The Howe Truss—The Use of Iron—Viaducts of Steel—The American System of Laying Bridge Foundations under Water—Origin of the Cantilever—Laying the Track—How it is Kept in Repair—Premiums for Section Bosses—Number of Railway Employees in the United States—Rapid Railway Construction—Radical Changes which the Railway will Effect.
Railways have been known since the days of the Romans. Their tracks were made of two lines of cut stones. Iron rails took their place about one hundred and fifty years ago, when the use of that metal became extended. These roads were called tram-roads, and were used to carry coal from the mines to the places of shipment. They were few in number and attracted little attention.
The modern railway was created by the Stephensons in 1830, when they built the locomotive "Rocket." The development of the railway since is due to the development of the locomotive. Civil engineering has done much, but mechanical engineering has done more.
The invention of the steam-engine by James Watt, in 1773, attracted the attention of advanced thinkers to a possible steam locomotive. Erasmus Darwin, in a poem published in 1781, made this remarkable prediction:
"Soon shall thy arm, unconquered steam! afar
Drag the slow barge, or drive the rapid car."
First Locomotive.
The first locomotive of which we have any certain record was invented, and put in operation on a model circular railway in London, in 1804, by Richard Trevithick, an erratic genius, who invented many things but perfected few. His locomotive could not make steam, and therefore could neither go fast nor draw a heavy load. This was the fault of all its successors, until the competitive trial of locomotives on the Liverpool and Manchester Railway, in 1829. The Stephensons, father and son, had invented the steam blast, which, by constantly blowing the fire, enabled the "Rocket," with its tubular boiler, to make steam enough to draw ten passenger cars, at the rate of thirty-five miles an hour.
Then was born the modern giant, and so recent is the date of his birth that one of the unsuccessful competitors at that memorable trial, Captain John Ericsson, was until the present year (1889) living and actively working in New York. Another engineer, Horatio Allen, who drove the first locomotive on the first trip ever made in the United States, in 1831, still lives, a hale and hearty old man, near New York.
The earlier locomotives of this country, modelled after the "Rocket," weighed five or six tons, and could draw, on a level, about 40 tons. After the American improvements, which we shall describe, were made, our engines weighed 25 tons, and could draw, on a level, some sixty loaded freight cars, weighing 1,200 tons. This was a wonderful advance, but now we have the "Consolidation" locomotive, weighing 50 tons, and able to draw, on a level, a little over 2,400 tons.
And this is not the end. Still heavier and more powerful engines are being designed and built, but the limit of the strength of the track, according to its present forms, has nearly been reached. It is very certain we have not reached the limit of the size and power of engines, or the strength of the track that can be devised.
After the success of the "Rocket," and of the Liverpool and Manchester Railway, the authority of George Stephenson and his son Robert became absolute and unquestioned upon all subjects of railway engineering. Their locomotives had very little side play to their wheels, and could not go around sharp curves. They accordingly preferred to make their lines as straight as possible, and were willing to spend vast sums to get easy grades. Their lines were taken as models and imitated by other engineers. All lines in England were made with easy grades and gentle curves. Monumental bridges, lofty stone viaducts, and deep cuts or tunnels at every hill marked this stage of railway construction in England, which was imitated on the European lines.
Locomotive of To-day.
As it was with the railway, so it was with the locomotive. The Stephenson type, once fixed, has remained unchanged (in Europe), except in detail, to the present day. European locomotives have increased in weight and power, and in perfection of material and workmanship, but the general features are those of the locomotives built by the great firm of George Stephenson & Son, before 1840.
When we come to the United States we find an entirely different state of things. The key to the evolution of the American railway is the contempt for authority displayed by our engineers, and the untrammelled way in which they invented and applied whatever they thought would answer the best purpose, regardless of precedent. When we began to build our railways, in 1831, we followed English patterns for a short time. Our engineers soon saw that unless vital changes were made our money would not hold out, and our railway system would be very short. Necessity truly became the mother of invention.
The first, and most far-reaching, invention was that of the swivelling truck, which, placed under the front end of an engine, enables it to run around curves of almost any radius. This enabled us to build much less expensive lines than those of England, for we could now curve around and avoid hills and other obstacles at will. The illustration opposite shows a railroad curving around a mountain and supported by a retaining wall, instead of piercing through the mountain with a tunnel, as would have been necessary but for the swivelling truck. The swivelling truck was first suggested by Horatio Allen, for the South Carolina Railway, in 1831; but the first practical use of it was made on the Mohawk and Hudson Railroad, in the same year. It is said to have been invented by John B. Jervis, Chief Engineer of that road.
The next improvement was the invention of the equalizing beams or levers, by which the weight of the engine is always borne by three out of four or more driving-wheels. They act like a three-legged stool, which can always be set level on any irregular spot. The original imported English locomotives could not be kept on the rails of rough tracks. The same experience obtained in Canada when the Grand Trunk Railway was opened, in 1854–55. The locomotives of English pattern constantly ran off the track; those of American pattern hardly ever did so. Finally, all their locomotives were changed by having swivelling trucks put under their forward ends, and no more trouble occurred. The equalizing levers were patented in 1838, by Joseph Harrison, Jr., of Philadelphia.
Alpine Pass. Avoidance of a Tunnel.
These two improvements, which are absolutely essential to the success of railways in new countries, and have been adopted in Canada, Australia, Mexico, and South America,[1] to the exclusion of English patterns, are also of great value on the smoothest and best possible tracks. The flexibility of the American machine increases its adhesion and enables it to draw greater loads than its English rival. The same flexibility equalizes its pressure on the track, prevents shocks and blows, and enables it to keep out of the hospital and run more miles in a year than an English locomotive.[2]
A Sharp Curve—Manhattan Elevated Railway, 110th Street, New York.
Equally valuable improvements were made in cars, both for passengers and freight. Instead of the four-wheeled English car, which on a rough track dances along on three wheels, we owe to Ross Winans, of Baltimore, the application of a pair of four-wheeled swivelling trucks, one under each end of the car, thus enabling it to accommodate itself to the inequalities of a rough track and to follow its locomotive around the sharpest curves. There are, on our main lines, curves of less than 300 feet radius, while, on the Manhattan Elevated, the largest passenger traffic in the world is conducted around curves of less than 100 feet radius. There are few curves of less than 1,000 feet radius on European railways.
A Steep Grade on a Mountain Railroad.
The climbing capabilities of a locomotive upon smooth rails were not known until, in 1852, Mr. B. H. Latrobe, Chief Engineer of the Baltimore and Ohio Railroad, tried a temporary zigzag gradient of 10 per cent.—that is 10 feet rise in 100 feet length, or 528 feet per mile—over a hill about two miles long, through which the Kingwood Tunnel was being excavated. A locomotive weighing 28 tons on its drivers took one car weighing 15 tons over this line in safety. It was worked for passenger traffic for six months. This daring feat has never been equalled. Trains go over 4 per cent. gradients on the Colorado system, and there is one short line, used to bring ore to the Pueblo furnaces, which is worked by locomotives over a 7 per cent. grade. These are believed to be the steepest grades worked by ordinary locomotives on smooth rails.
Another American invention is the switchback. By this plan the length of line required to ease the gradient is obtained by running backward and forward in a zigzag course, instead of going straight up the mountain. As a full stop has to be made at the end of every piece of line, there is no danger of the train running away from its brakes. This device was first used among the hills of Pennsylvania over forty years ago, to lower coal cars down into the Nesquehoning Valley. It was afterwards used on the Callao, Lima, and Oroya Railroad in Peru, by American engineers, with extraordinary daring and skill. It was employed to carry the temporary tracks of the Cascade Division of the Northern Pacific Railroad over the "Stampede" Pass, with grades of 297 feet per mile, while a tunnel 9,850 feet long was being driven through the mountains.
A Switchback.
With the improvement of brakes and more reliable means of stopping trains upon steep grades, came a farther development of the above device, which was first applied on the Denver and Rio Grande Railroad in Colorado, and has since been applied on a grand scale on the Saint Gothard road, the Black Forest railways of Germany, and the Semmering line in the Tyrol. This device is to connect the two lines of the zigzag by a curve at the point where they come together, so that the train, instead of going alternately backward and forward, now runs continuously on. It becomes possible for the line to return above itself in spiral form, sometimes crossing over the lower level by a tunnel, and sometimes by a bridge. A notable instance of this kind of location is seen on the Tehachapi Pass of the Southern Pacific, where the line ascends 2,674 feet in 25 miles, with eleven tunnels, and a spiral 3,800 feet long.
Plan of Big Loop.
The "Big Loop," as it is called, on the Georgetown branch of the Union Pacific, in Colorado, between Georgetown and a mining camp called Silver Plume, has been chosen to illustrate this point. The direct distance up the valley is 1¼ miles and the elevation 600 feet, requiring a gradient of 480 feet per mile. But by curving the line around in a spiral, the length of the line is increased to 4 miles and the gradient reduced to 150 feet per mile. Zigzags were used first for foot-paths, then for common roads, lastly for railways. Their natural sequence, spirals, was a railway device entirely, and confirms the saying of one of our engineers: "Where a mule can go, I can make a locomotive go." This may be called the poetry of engineering, as it requires both imagination to conceive and skill to execute.
Profile of the Same.
There is one thing more which distinguishes the American railway from its English parent, and that is the almost uniform practice of getting the road open for traffic in the cheapest manner and in the least possible time, and then completing it and enlarging its capacity out of its surplus earnings, and from the credit which these earnings give it.
Big Loop, Georgetown Branch of the Union Pacific, Colorado.
The Pennsylvania Railroad between Philadelphia and Harrisburg is a notable example of this. Within the past few years it has been rebuilt on a grand scale, and in many places relocated, and miles of sharp curves and heavy gradients, originally put in to save expense, have been taken out. This system has been followed everywhere, except on a few branch lines, and upon one monumental example of failure—the West Shore Railroad, of New York. The projectors of that line attempted in three years to build a double-track railroad up to the standard of the Pennsylvania road, which had been forty years in reaching its present excellence. Their money gave out, and they came to grief.
We have thus briefly reviewed the development of our railways to show what they are, and how they came to be what they are, before describing the processes of building, in order that the reasons may be clearly understood why we do certain things, and why we fail to do other things which we ought to do.
In the building of a railway the first thing is to make the surveys and locate the position of the intended road upon the ground, and to make maps and sections of it, so that the land may be bought and the estimates of cost be ascertained. The engineer's first duty is to make a survey by eye without the aid of instruments. This is called the "reconnoissance." By this he lays down the general position of the line, and where he wants it to go if possible. Great skill, the result of long experience, or equally great ignorance may be shown here. After the general position of the line, or some part of it, has been laid down upon the pocket map, the engineer sends his party into the field to make the preliminary survey with instruments.
In an old-settled country the party may live in farm-houses and taverns, and be carried to their daily work by teams. But a surveying party will make better progress, be healthier and happier, if they live in their own home, even if that home be a travelling camp of a few tents. With a competent commissary the camp can be well supplied with provisions, and be pitched near enough to the probable end of the day's work to save the tired men a long walk. When they get to camp and, after a wash in the nearest creek, find a smoking-hot supper ready—even though it consist of fried pork and potatoes, corn-bread and black coffee—their troubles are all forgotten, and they feel a true satisfaction which the flesh-pots of Delmonico's cannot give. One greater pleasure remains—to fill the old pipe, and recline by the camp-fire for a jolly smoke.
Engineers in Camp.
A full surveying party consists of the front flag-man, with his corps of axe-men to cut away trees and bushes; the transit-man, who records the distances and angles of the line, assisted by his chain-men and flag-men; and lastly the leveller, who takes and records the levels, with his rod-men and axe-men. The chief of the party exercises a general supervision over all, and is sometimes assisted by a topographer, who sketches in his book the contours of the hills and direction and size of the watercourses.
One tent contains the cook, the commissary, and the provisions; another tent or two the working party, and another the superior engineers, with their drawing instruments and boards. In a properly regulated party the map and profile of the day's work should be plotted before going to bed, so as to see if all is right. If it turns out that the line can be improved and easier grades got, or other changes made, now is the time to do it.
After the preliminary lines have been run, the engineer-in-chief takes up the different maps and lays down a new line, sometimes coinciding with that surveyed, and sometimes quite different. The parties then go back into the field and stake out this new line, called the "approximate location," upon which the curves are all run in. In difficult country the line may be run over even a third or fourth time; or in an easy country, the "preliminary" surveys may be all that is wanted.
The life of an engineer, while making surveys, is not an easy one. His duties require the physical strength of a drayman and the mental accuracy of a professor, both exerted at the same time, and during heat and cold, rain and shine.
An engineer, once on a time, standing behind his instrument, was surrounded by a crowd of natives, anxious to know all about it. He explained his processes, using many learned words, and flattered himself that he had made a deep impression upon his hearers. At last, one old woman spoke up, with an expression of great contempt on her face, "Wall! If I knowed as much as you do, I'd quit ingineerin' and keep a grocery!"
A large part of the financial difficulties of our railways results from not taking time enough to properly locate the line. It must be remembered that a cheaply constructed line can be rebuilt, but with a badly located line nothing can be done except to abandon it entirely.
Royal Gorge Hanging Bridge, Denver and Rio Grande, Colorado.
It is well therefore to consider carefully what is the true problem of location. It is so to place and build a line of railway that it shall get the greatest amount of business out of the country through which it passes, and at the same time be able to do that business at the least cost, including both expenses of operating and the fixed charges on the capital invested. The mere statement of this problem shows that it is not an easy one. Its solution is different in a new and unsettled country from that in an old-settled region. In the new country, the shortest, cheapest, and straightest line possible, consistent with the easiest gradients that the topography of the land will allow, is the best. The towns will spring up after the road is built, and will be built on its line, and generally at the places where stations have been fixed.
Veta Pass, Colorado.
In a mountainous country, like Colorado, the problem is how to reach the important mining camps, regardless of the crookedness and increased length given to the line. The Denver and Rio Grande has been compared to an octopus. This is really a compliment to its engineers. It sucks nutriment from every place where nutriment is to be found. To do this it has been forced to climb mountains, where it was thought locomotives could never climb. In one place, called the Royal Gorge, the difficulties of blasting a road-bed into the side of the mountain were so great that it was thought expedient to carry the track upon a bridge, and this bridge was hung from two rafters, braced against the sides of the gorge. In surveying some parts of the lines the engineers were suspended by ropes from the top of the mountains and made their measurements swinging in mid-air.
Sections of Snow-sheds.
The problem of location is different in an old-settled country, where the position of the towns as trade-centres has been fixed by natural laws that cannot be overruled. In this case the best thing the engineer can do is to get the easiest gradient possible consistent with the topography of the country, and let the curves take care of themselves; always to strike the important towns, even if the line is made more crooked and longer thereby; to so place the line in these towns as to accommodate the public, and still be able to buy plenty of land; also to locate for under or over, rather than grade crossings.
In all countries, old and new, mountainous and level, the rule should be to keep the level of track well above the surface of the ground, in order to insure good drainage and freedom from snow-drifts.
The question of avoidance of obstruction by snow is a very serious one upon the Rocky Mountain lines, and they could not be worked without the device of snow-sheds—another purely American invention. There are said to be six miles of stanchly built snow-sheds on the Canadian Pacific and sixty miles on the Central Pacific Railway. The quantity of snow falling is enormous, sometimes amounting to 250,000 cubic yards, weighing over 100,000 tons, in one slide. It is stated by the engineers of the Canadian Pacific, that the force of the air set in motion by these avalanches has mown down large trees, not struck by the snow itself. Their trunks, from one to two feet in diameter, remain, split as if struck by lightning.
Snow-sheds, Selkirk Mountains, Canadian Pacific. The winter track under cover; the outer track for summer use.
After the railway line has been finally located, the next duty of the engineers is to prepare the work for letting. Land-plans are made, from which the right of way is secured. From the sections, the quantities are taken out. Plans of bridges and culverts are made; and a careful specification of all the works on the line is drawn up.
Making an Embankment.
The works are then let, either to one large contractor or to several smaller ones, and the labor of construction begins. The duties of the engineers are to stake out the work for the contractors, make monthly returns of its progress, and see that it is well done and according to the specifications and contract. The line is divided into sections, and an engineer, with his assistants, is placed in charge of each. Where the works are heavy, the contractors build shanties for their men and teams near the heavy cuttings or embankments. It is the custom to take out heavy cuttings by means of the machine called a steam shovel, which will dig as many yards in a day as 500 men.
Steam Excavator.
On the prairies of the West the road-bed is thrown up from ditches on each side, either by men with wheelbarrows and carts, or by means of a ditching-machine, which can move 3,000 yards of earth daily. In this case the track follows immediately after the embankment, and the men live in cars fitted up as boarding-shanties, and moved forward as fast as required. If the country contains suitable stone, the culverts and bridge abutments are built by gangs of masons and stone-cutters, who move from point to point. But the general practice is to put in temporary trestle-work of timber resting upon piles, which trestle-work is renewed in the shape of stone culverts covered by embankments, or iron bridges resting on stone abutments and built after the road is running.
Building a Culvert.
The pile-driver plays a very important part therefore in the construction of our railroads, and has been brought to great perfection. It is worked by a small boiler and engine, and gives its blows with great rapidity. It drags the piles up to leaders and lifts them into place by steam-power, so that it is worked by a small gang of men. Finally, it is as portable as a pedler's cart, and as soon as it has finished one job it is taken to pieces, packed upon wagons, and moved on to the next job.
Tunnels are neither so long nor so frequent upon American railways as upon those of Europe. The longest are from two to two and a half miles long, except one, the Hoosac, about four miles. Sometimes they are unavoidable. The ridge called Bergen Hill, west of Hoboken, N. J., is a case in point. This is pierced by the tunnels of the West Shore, of the Delaware, Lackawanna, and Western, and of the Erie, the last two of which, as shown on page 25, are placed at different levels to enable one road to pass over the other.
Rock Drill.
It is by our system of using sharp curves that we avoid tunnels. It may be said, in general terms, that American engineers have shown more skill in avoiding the necessity of tunnels than could possibly be shown in constructing them. When we are obliged to use tunnels, or to make deep cuttings in rocks, our labors are greatly assisted by the use of power-drills worked by compressed air and by the use of high explosives, such as dynamite, giant powder, rend-rock, etc. Rocks can now be removed in less than half the time formerly required, when ordinary blasting-powder was used in hand-drilled holes.[3]
A Construction and Boarding Train.
From data furnished by Mr. D. J. Whittemore, chief engineer of the Chicago, Milwaukee, and St. Paul system (which had a total length of 5,688 miles on January 1, 1888), the length of open bridges on these lines was 11591/100 miles, and of culverts covered over with embankment, 392/10 miles. "Everything," says Mr. Whittemore, "not covered with earth, except cattle guards, be the span 10 or 400 feet, is called a bridge. Everything covered with earth is called a culvert. Wherever we are far removed from suitable quarries, we build a wooden culvert in preference to a pile bridge, if we can get six inches of filling over it. These culverts are built of roughly squared logs, and are large enough to draw an iron pipe through them of sufficient diameter to take care of the water. We do this because we believe that we lessen the liability to accident, and that the culvert can be maintained after decay has begun, much longer than a piled bridge with stringers to carry the track. Had we good quarries along our line, stone would be cheaper. Many thousands of dollars have been spent by this company in building masonry that after twenty to twenty-five years shows such signs of disintegration that we confine masonry work now only to stone that we can procure from certain quarries known to be good."
Bergen Tunnels, Hoboken, N. J.
Mr. Whittemore is an engineer of great experience, skill, and judgment, and there is food for much reflection in these words of his: First—that it is better to use temporary wooden structures, to be afterward renewed in good stone, rather than to build of the stone of the locality, unless first-class. Second—that a structure covered with earth is much safer than an open bridge; which, if short and apparently insignificant, may be, through neglect, a most serious point of danger, as was shown in the dreadful accident of 1887 on the Toledo, Peoria, and Western road in Illinois, where one hundred and fifty persons were killed and wounded, and by the equally avoidable accident on the Florida and Savannah line, in March, 1888. Had these little trestles been changed to culverts covered with earth, many valuable lives would not have been lost.
Beginning a Tunnel.
It was safely estimated that there were, in 1888, 208,749 bridges of all kinds, amounting in length to 3,213 miles, in the United States.[4]
The wooden bridge and the wooden trestle are purely American products, although they were invented by Leonardo da Vinci in the sixteenth century. From the above statistics it will be seen how much our American railways owe to them, for without them over 150,000 miles could never have been built.
The art of building wooden truss-bridges was developed by Burr & Wernwag, two Pennsylvania carpenters, some of whose works are still in use after eighty years of faithful duty (p. 28). A bridge built by Wernwag across the Delaware in 1803 was used as a highway bridge for forty-five years, was then strengthened and used as a railway bridge for twenty-seven years more, and was finally superseded by the present iron bridge in 1875.
These old bridge-builders were very particular about the quality of their timber, and never put any into a bridge less than two years old. But when we began to build railways, everything was done in a hurry, and nobody could wait for seasoned timber. This led to the invention of the Howe truss, by the engineer of that name, which had the advantage of being adjustable with screws and nuts, so that the shrinkage could be taken up, and which had its parts connected in such a way that they were able to bear the heavy concentrated weight of locomotives without crushing. This bridge was used on all railways, new and old, from 1840 to about 1870. Had it been free from liability to decay and burn up, we should probably not be building iron and steel bridges now, except for long spans of over 200 feet; and as the table opposite shows, the largest number of our spans are less than 100 feet long.
The Howe truss forms an excellent bridge, and is still used in the West on new roads, with the intention of substituting iron trusses after the roads are opened.
After 1870, the weights both of locomotives and other rolling stock began to be increased very rapidly. This, together with the development of the manufacture of iron, and especially the invention of rolled beams and of eye-bars, gave a great impetus to the construction of iron bridges. At first cast-iron was used for the compression members, but the development of the rolling-mill soon enabled us to make all parts of rolled iron sections at no greater cost, and rolled iron, being a less uncertain material, has replaced cast-iron entirely. Iron bridges came in direct competition with the less costly Howe truss, and during the first decade of their construction every attempt was made to build them with as few pounds of iron as would meet the strains.
Old Burr Wooden Bridge.
S. Whipple, C.E., published a book in 1847 which was the first attempt ever made to solve the mathematical questions upon which the due proportioning of iron truss-bridges depends. This work bore fruit, and a race of bridge designers sprang up. The first iron bridges were modelled after their wooden predecessors, with high trusses and short panels. Riveted connections were avoided, and every part was so designed that it might be quickly and easily erected upon staging or false works, placed in the river. This was very necessary, for our rivers are subject to sudden freshets, and if we had adopted the English system of riveting together all the connections, the long time required before the bridge became self-sustaining would have been a serious element of danger.
Following the practice of wooden bridge building, iron bridges were contracted for by the foot, and not by the pound as is now the custom. To this accidental circumstance is greatly due the development of the American iron bridge. The engineer representing the railway company fixed the lengths of spans, and other general dimensions, and also the loads to be carried and the maximum strains to be allowed. The contracting engineer was left perfectly free to design his bridge, and he strained every nerve to find the form of truss and the arrangement of its parts that should give the required strength with the least number of pounds weight per foot, so that he could beat his competitors. When the different plans were handed in, an expert examined them and rejected those whose parts were too small to meet the strains. Of those found to be correctly proportioned, the lowest bid took the work.
By the rule of the survival of the fittest all badly designed forms of trusses disappeared and only two remained: one the original truss designed by Mr. Whipple, and the other, the well-known triangular, or "Warren" girder, so called after its English inventor.
It speaks well for the skill and honesty of American bridge engineers that many of their old bridges are still in use, designed for loads of 2,500 pounds per lineal foot, and now daily carrying loads of 4,000 pounds and over per foot. Sometimes the floor has been replaced by a stronger one, but the trusses still remain and do good service. The writer may be permitted to point to the bridge over the Mississippi River at Quincy, Ill., built in 1869, as an example. Most bridge-accidents can be traced to derailed trains striking the trusses and knocking them down. Engineers (both those specially connected with bridge works, and those in charge of railways) know much better now what is wanted, and the managers of railways are willing to pay for the best article. The introduction of mild steel is a great step in advance. This material has an ultimate strength, in the finished piece, of 63,000 to 65,000 pounds per square inch, or forty per cent. more than iron, and it is tough enough to be tied in a knot, or punched into the shape of a bowl, while cold. With this material it is as easy to construct spans of 500 feet as it was spans of 250 feet in iron.
Bridges are now designed to carry much heavier loads than formerly. The best practice adopts riveted connections except at the junction of the chord-bars and the main diagonals, where pins and eyes are still very properly used. Plate girders below the track are preferred up to 60 or 70 feet long, then riveted lattice up to 125 feet. The wind strains also are now provided for with a considerable excess of material, amounting in very long spans to nearly as much as the strains due to gravity. Observing the rule that no bridge can be stronger than its weakest part, a vast deal of care and skill has been applied in perfecting the connections of the parts of a truss, and many valuable experiments have been made which have greatly enlarged our knowledge of this difficult subject. The introduction of riveting by the power of steam or compressed air is another very great improvement.[5]
Kinzua Viaduct; Erie Railway.
Valleys and ravines are now crossed by viaducts of iron and steel, of which the Kinzua viaduct, illustrated here, is an example. A branch line from the Erie, connecting that system with valuable coal-fields, strikes the valley of the Kinzua, a small creek, about 15 miles southwest of Bradford, Pa. At the point suitable for crossing, this ravine is about half a mile wide and over 300 feet deep. At first it was proposed to run down and cross the creek at a low level by some of the devices heretofore illustrated in this article. But finally the engineering firm of Clarke, Reeves & Co. agreed to build the viaduct, shown above, for a much less sum than any other method of crossing would have cost. This viaduct was built in four months. It is 305 feet high and about 2,400 feet long. The skeleton piers were first erected by means of their own posts, and afterward the girders were placed by means of a travelling scaffold on the top, projecting over about 80 feet. No staging of any kind was used, nor even ladders, as the men climbed up the diagonal rods of the piers, as a cat will run up a tree.
The Manhattan Elevated Railway, about 34 miles long, is nothing but a long viaduct, and is as strong and durable as iron viaducts on railways usually are, while from the slower speed of its trains it is much safer.
Kinzua Viaduct.