Artistic bridge design: a systematic treatise on the design of modern bridges according to aesthetic principles

Front matter

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BRIDGE AT HELL GATE, NEW YORK. SPAN 1,000 FEET.

Preface

A lack of artistic treatment is the greatest fault of American bridges. These structures are worthy of greater thought and study because they are usually such conspicuous objects in the landscape. The lack of art is no doubt partly due to the dearth of literature on the subject and the difficulty in securing good illustrations, and it is hoped that this book will assist in producing better results.

The most important work in connection with any great building enterprise is the preparation of the design, for on this the success or failure of the project depends. If the design is faulty, the money, time and thought spent on its construction are largely wasted, and all the labor of engineers, contractors and artisans is lost. If the design is lacking in beauty, the structure may remain for centuries as a mockery to its originators,, unless fortunately it should collapse through structural weakness and give place to another one, more worthy.

The impression has long prevailed that bridge design consists in the development of formulae, the solution of problems in graphic statics and the computation of stresses in truss frames; whereas, this is not design at all, but merely a part of the process in producing a design. Almost no attention has been given by engineers in America to the artistic character of bridges, and but little to their proper proportions, or to the selection of economic types. For fifty years mathematicians wrestled with purely constructive problems, evolving formulae and establishing tlieir conclusions, and in this direction there is little left to be desired; but during this time little improvement was made in the visible appearance of their creations. It remains, therefore, for the engineers of the twentieth century to insist upon and to establish a higher standard of bridge y

PREFACE

design, based upon the combined standards of economic proportions and aesthetic appearance. Engineers are frequently deficient in artistic training and taste, and architects in constructive knowledge, and the need of improvement is generally admitted. The tendency in this direction is shown by the cooperation between engineers and architects on many of the largest structures, particularly the proposed bridges for New York and Washington.

Mr.'Gustav Lindenthal, who is an unquestioned authority on bridge building, says: "It cannot be denied that America is behind the standards of Europe in aesthetic construction. There, the more important bridges, particularly in cities, are invariably designed with a view to their architectural appearance. Details of construction are subordmated to it. The American practice is regulated more from the standpoint of utility, of quick fabrication and speedy erection, not always with the happiest results architecturally. Although the United States has the largest number of steel and iron bridges, it has also the distinction of having the ugliest. There are certain indications, however, of an improvement in taste and it is entirely within the possibilities of the near future that American engineers will be able in foreign competitions to furnish designs for bridges at once architecturally meritorious and economic of cost."

During the writer's twenty-five years experience he has made designs for several hundred bridges, many of which were built, and the suggestions in this book are the outcome of his effort and study to control dominant commercialism which has caused engineers to perpetrate so much vandalism. The book is the development of a series of articles on ornamental bridge construction, written by him and published in The American Architect in 1901, though more than fifty half-tones used in those articles have not been reproduced here. The number of illustrations might easily have been increased, only a few being included from the writer's collection of more than a thousand photographs. Certain principles of design have occasionally

PREFACE

been repeated in different chapters, where it appeared desirable for the sake of emphasis or clearness.

There is perhaps no one better able to write on the subject than Mr. Thomas Hastings, who has furnished the introductory chapter, for the work of his firm, Carrere & Hastings, on the great bridges of New York, is very well known. I have received valuable suggestions and illustrations also from Mr. Whitney Warren, architect of the proposed Hudson Memorial bridge, and from Mr. Paul Pelz, architect in chief of the Congressional Library, and designer of the proposed Potomac Memorial bridges at Washington.

In the preparation of this work, I have been assisted by my wife, Maude K. Tyrrell, who is a graduate of the Chicago Art Institute, with practical experience in architectural design.

Some illustrations of European bridges were supplied to mc complimentarily by the "Gutehoffnungshiitte" of Oberhausen, Germany, and a few others were secured from The Concrete-Steel Engineering Company of New York. Benefit has been derived from discussions and illustrations which have appeared in various periodicals and journals, including The Engineer and Engineering of London, Genie Civil, Annales des Ponts et Chaussees, Revue Industrielle, Nouvelles Annales de la Construction, Revista de Obras Publicas, Glaser's Annaien fiir Gewerbe und Bauwesen, Zeitschrift fiir Bauwesen, Zentralblatt der Bauverwaltung, Beton und Eisen, Stahl und Eisen, Zeitschrift des Vereines Deutscher Ingenieure, Zeitschrift der Oesterreichischen Ingenieur und Architeckten Verein, Allgemeine Bauzeitung, Deutsche Bauzeitung, Annales des travaux publics de Belgique, De Ingenieur, Tijdschrift van het. K. Inst, van Ing., Schweizerische Bauzeitung, Giornale del Genio Civile, Engineering News, Engineering Record, Metropolitan Magazine, Architectural Record, Scientific American, etc., as well as reports from many American and foreign technical and scientific societies.

August, 191 1.

Table Of Contents

Introduction by Thomas Hastings chapter page

I Importance of Bridges 9

Magnitude of Subject 11

Introduction

BY THOMAS HASTINGS

Among all the varied problems of construction which present themselves to human ingenuity, it may be said that the bridge most influences the landscape or transforms the general character of a city. From a rustic bridge which crosses the brook, lending interest to the woodland scenery, to the impressive construction which spans the mighty river without interrupting its circulation, whatever may be its purpose, there is nothing human which may add more to the beauty of a landscape or may so seriously detract from it.

Man more than any other animal has always been migratory, penetrating the most distant regions, and to this end he encircles the world with railroads, pierces the mountains with tunnels, or crosses the intervening valleys with bridges or roads, giving a human interest to nature which, in its primeval condition, it never had. There is no more lasting or permanent construction than that of the bridge, because it does not give way to the changing conditions of the country, or to the growth and development of the city, as does almost any other architectural structure. It is therefore evident that the most serious thought should be given to the character and design of such lasting monuments.

New York is destined to have more bridges of colossal size than perhaps any other great city of the world. The geographical conditions which are most natural, almost like those of Venice, isolate the city on an island, and this island is becoming more and more overcrowded. The large bodies of water in the immediate neighborhood of the metropolis impose varied conditions upon the bridge builder, which will for many generations to come bring about wonderful developments in this relation; and let us hope that these great bridges will make the city more beautiful. If only municipal authorities continue to take the intelligent interest which some administrations have manifested, this hope may be realized. It would be difficult to picture how beautiful the future city might become when in time these bridges make their impress upon the many miles of water front. We have indeed made too little of these natural conditions and have too seldom realized how much the large bodies of water — the Sound, the Ocean and the Rivers — mean to the inhabitants of the city, not only for purposes of navigation and pleasure, but also for comfort and beauty. These waters, whose tides twice a day bathe our shores, mean more to us than we can realize, and to appreciate this one need only to visit some western inland town to feel a real longing for a coast environment.

New York has grown too large for Manhattan Island, and it must reach out and over the waters as well as under them. Our highways must be extended, giving most interesting problems to the engineer and the architect for many generations to come. Let us hope that the authorities who are doing so much in this direction will some day force the railroads to have more respect for private property instead of destroying, as is so often done, the entire appearance of those portions of the towns they pass through, seeing only the commercial side or how m'uch money can be drained from an ever patient but constantly moving and growing population. It is pitiable indeed to note how often, especially in smaller cities, the railroads build walls through the heart or center of a town, and make them none too good for mere cellar construction with ugly guard rails of pipe, without the slightest consideration of the feelings of the property owners. When one considers the enormous cost of hundreds of miles of railroads from place to place, it is apparent how comparatively small w^ould be the increased expenditure if some thought were given to making such constructions in some way add to the character of any railroad town.

Since the recent manufacture of wrought iron and steel in

INTRODUCTION 3

large quantities these metals have in a great measure taken the place of the use of stone or wood in bridge construction; this has had a very great influence upon architectural development of bridges. The influence was most generally felt in the building of railroads in the first part of the nineteenth century. There is on record, however, a design made by Thomas Paine, the author, for an iron bridge in the year 1 786. It was a segmental arch and this design has formed the basis of many cast iron arched bridges since built. The model for this bridge was placed on exhibition in the house of Benjamin Franklin in Philadelphia, and was afterwards sent to Paris, where it was exhibited at the Academy of Sciences.

It was not until 1840 that any great iron bridges were built in this country, excepting suspension bridges, where iron links were used in the cables and suspenders, the floors being of wood. To realize the great influence railroads have had upon bridge building, we must consider the fact that prior to 1860 the bridges for the railroads were generally designed by the railroad engineers and executed in the shops of the railroad companies. This made an emergency demand, and naturally little thought was given to aesthetics or to the permanent character of such constructions. Later the railroads gave the building of these bridges to construction companies who furnished both designs and bids at the same time, and it is only in recent years that the engineers in this class of work have emerged from these construction companies to enter into the general practice of this profession. In designing bridges and writing specifications their designs were to become the property of the railroad companies, so that they might obtain competitive bids from different contractors.

It is unfortunate that many, though by no means all, of our highway bridges have been designed by engineers who have obtained their education through these channels, so it is not surprising that there has been a marked disregard for the architect and his work. Unquestionably until modern times, most engineers knew more about architecture than they do today.

as also did architects know more about engineering, but with this modern tendency of differentiation and with the multitude of complicated problems brought about by iron construction, there must be more collaboration between engineer and architect in order to produce better results from the practical, as well as from the artistic point of view. This would, indeed, be an advantage not only in that it would make the bridge more beautiful, but there would be an economy of time and money if the engmeer and architect would unite in the design. From the first they would work hand in hand to scheme the bridge, instead of the architects being called in at the last moment, as is so often done, merely to design lamp posts, balustrades and other minor details. Planning and designing together, the architect and engineer would produce most satisfactory results. In matters of construction, the architect mainly sees the qualitative side of things, while the engineer s&es the quantitative side. A thing builds well that looks well and that follows the laws of architectural proportion and is unquestionably more economical. Alas, a strange sense is that sense of beauty whose absence is as often wanting in human character as is the sense of humor, and the man is as unconscious of this shortcoming in the one case as in the other. He sometimes even seems to have a sort of disdain for any thought of the beautiful, and the deplorable mistakes he makes because of this fact are as incurable and as incorrigible as are hereditary maladies. He shows a total lack of respect for precedents, or the things which have been done in the past. He little realizes that in the history of civilization most things have been destroyed or taken down which were only practical. I really believe that in our conduct of life even a moral law would not be adhered to unless it were in some way and somehow beautifully expressed.

Leaving the architect out altogether in the scheming of a bridge is as though he were to be left out in the designing of tall buildings, because so-called skeleton construction has come into the building practice. Such tall buildings are bad enough

INTRODUCTION 5

as it is, but they would not be endurable if there were to be an exhibition in our public streets of their unclothed and unadorned skeletons.

There is great hope for the future development of bridges in that there seems to be a tendency among financiers more closely to consider the question of maintenance as related to original cost in large construction enterprises, and this will unquestionably induce them to build more largely of stone and brick than has been the case until this generation. In fact, it is already the policy of the Pennsylvania Railroad to build stone bridges wherever practicable. It means much for art. To everything there is a season, and a time for every purpose under the heavens. ^_-.

In the construction of stone bridges the Romans were the first great builders. Bridge building was, in fact, one of the most interesting problems they had to solve. In architecture and construction they were indeed a most original and artistic people; too little appreciated and studied by modern Anglo- Saxons. They were the forerunners of our present constructors. Until their time the Greeks had reached that measure of perfection now so much considered, and theirs was the culmination of the slow artistic development through the ages. The Romans, however, had presented to them untried problems to be solved which called for new methods of construction, and of these the bridge or aqueduct was one of the most interesting. They were practically the first people to use the principle of the arch and voussoir construction. The use of the arch principle, while sometimes attributed to the Chinese, was practically unknown to the ancients of the Western civilization until the Roman conquest. It has been contended that the idea of the arch principle was first evolved by the Etruscans. If this is true, it is indeed coming near to Rome.

Such wonderful bridges as the one built by Caesar Augus- f tus at Rimini or the Pont du Gard, the great aqueduct situated about twenty miles from Nimes, built across the river Gard, and attributed to Agrippa; the bridge of St. Augustus at Rome, started by Adrian, and many others too numerous to mention have scarcely ever been surpassed. There seems to have been a period between this time and the twelfth century when few bridges of importance were built, and it was between the years 1 1 78 and 1 1 88 that the famous bridge of St. Benezet, at Avignon, was built. Several other beautiful bridges soon followed, similar to it in construction. Then came the early Renaissance bridges, also too numerous to mention — the old Pont Neuf being, perhaps, the finest in Paris; the famous bridge attributed to Ammanati, the architect, in the sixteenth century, at Florence ; also the largest stone bridge ever built in the world, with a span of one hundred and eighty-three feet and a rise of sixty feet over the Allier at Vielle Brioude, France; or the bridge at Chester over the Dee, forty feet high with two hundred feet span.

Finally, we come to modern times full of interesting examples too innumerable to catalogue, excepting, perhaps, a few in our immediate neighborhood. The bridges around New York are more interesting from the engineering point of view than from the artistic. It would seem almost a sacrilege to criticise the old Brooklyn bridge, either from the architectural or the engineering standpoint. It is too much a part of us which we have learned to revere rather than to criticise ; nor will I criticise the new Williamsburg bridge. I refrain from criticism on general principles, because I believe criticising individual work often does more harm than good.

When we were asked to design in collaboration with the engineers, the new Manhattan bridge, before beginning studies we rode in an automobile over the Brooklyn bridge, returning by way of the Williamsburg bridge. We were much impressed with the added interest in the Brooklyn bridge, due to the fact that the towers of that old structure were of stone rather than of iron, giving more color and variety to the composition. We felt greatly the need of stone above the roadbed in the proposed Manhattan bridge, the third large one to be built across the East river; and with this in view we took advantage of the

INTRODUCTION 7

great masonry anchorage necessary to receive the four cables pulling each at about the rate of ten millions of pounds. We felt that the masonry should be indicated above the roadbed, and with this in view we designed a colonnade, forming a courtyard of stone as large as a city block and one hundred and twenty-five feet above the water, making a vivid contrast with the necessary forest of iron work.

A much mooted question in the newspapers and elsewhere was whether these bridges were all to be made through thoroughfares, and with this in view, we were asked to design a station at the entrance to the old Brooklyn bridge. An interesting condition confronted us, and one which the critics of this project do not seem to understand. We were asked to design this station in such a way that it should meet the conditions then existing, and at the same time to so build that it would be possible at a small expense to adapt it to new conditions in case of through traffic. In this case such a station would not be a terminal, but a stopping place on the way. It is unfortunate that this fact has been so little understood, as I believe it would silence much opposition. The problem as presented to us by the Bridge Department was in other ways most interesting. It was proposed to design a building in such a way that a vista through a great triumphal entrance arch, showing the old stone towers, might be obtained by people walking on Broadway or in the City Hall Park. Here is one of the greatest bridges in the world, and yet, with the present deplorable and unpractical entrance, one does not know when in this neighborhood that the bridge exists until one is actually launched half way out on its roadbed.

All tramways or trains on the level of the roadbed of the bridge would, according to the new plan, go under ground, and those that are elevated would remain elevated at the entrance, to the height of twenty-five feet, so as to make the desired vista possible. This at the same time would be a wonderful relief to the congestion at this point, because the entire ground floor would be free and open for circulation.

while the waiting rooms or stations would be above and below. This was one of the most interesting architectural problems we have ever had to study, and if carried out, it would offer for further study a most engaging architectural problem. The development of a great city is an evolution, and we need make no effort to find ways to beautify the city ; they exist everywhere if we will but recognize them when they are offered.

CHAPTER I Importance of Bridges

The condition and character of bridges, roads and other public utilities have been measures of civilization in all ages. The homeless savage in trackless wilds had little need for bridges, as his wants were few and achievements small. But as civilization dawned, human needs increased and the desire for greater comforts, better homes and surroundings created a need for transportation and communication. The bridge of fallen logs or swinging vines (Fig. 1 *) gave place to better and

Fig. 1

more commodious ones, over which loaded animals and carts could pass with safety. With the further advance of civilization and the extension of commerce, heavier and better bridges were required, until the coming of railroad transportation in the nineteenth century, when stronger ones were erected to carry trains of cars and locomotives. The earliest bridges, like houses and other structures, were for utility only, and little or no thought was given to their adornment. Primitive races were content with homes which merely sheltered them from the storm and with rude bridges which served only their barest needs (Fig. 2*), but succeeding generations produced buildings in which utility was combined with art. While houses have been adorned and made architecturally attractive, the beautify-

* From "History of Bridge Engineering," by H. G. Tyrrell.

ing of bridges has not advanced in proportion to other arts. Many cities which have splendid buildings, streets and parks, are disfigured with utilitarian bridges, wholly void of art and worthy of existence only in remote regions. The greatest lack of art in bridges is found in America and other new countries, where the need of rapid construction has prevented aesthetic treatment.

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Fig. 2

As the latter part of the nineteenth century was an era in which bridges of great proportions were erected, so the first part of the tv/entieth century will doubtless witness the beginning and development of bridge architecture in America. Progress in this direction is strikingly illustrated in the city of New York. Thirty years ago the Brooklyn bridge (Fig. 235) was erected as a great utilitarian structure with little or no thought for its adornment, but on some of the later bridge designs in that city, the carrying out of which has unfortunately been prevented by other interests, a great amount of art has been displayed.

Great bridges are a distinctive feature of modern cities and, according as they are attractive or not, they influence public estimation of the place in which they are located. The beautiful bridges of Paris, Berlin and Budapest are of enough interest in themselves to attract travelers to those cities, and the bridges over the Rhine are among the principal features of the region. Progress in America is well illustrated by comparing the old King's and Farmer's bridges at New York, of the seventeenth and eighteenth centuries, with the four great ones over the East river which are the most conspicuous objects in the landscape.

IMPORTANCE OF BRIDGES 11

MAGNITUDE OF SUBJECT

v^Since the middle of the nineteenth century bridge building has developed into one of the greatest of modern enterprises.^ In the United States alone there are about 80,000 metal bridges with an aggregate length of 1 ,400 miles, or one bridge for every three miles of railroad. In addition to this there are about 200,000 wooden trestles with an aggregate length of about 3,000 miles. The largest ones are those over the great continental rivers of Europe, Asia and America, the most important being in America. Metal bridges in America alone are valued at $800,000,000, and the building of them has given employment directly or indirectly to many thousands of men. Mines are equipped and operated to produce the ore and coal, rolling mills to make the finished shapes and plates, and bridge and structural works to fabricate the parts. Other industries are employed in making machinery, tools and supplies for the mines, rolling mills and shops, and still others are engaged in supplying the wants and equipment of those who manufacture the tools. A large amount of capital is, therefore, invested not only in the bridges themselves but also in the mines, mills and shops for producing them. Shipping them gives business to railroad and steamship lines, and the work of erection gives employment to many workmen. The making of travelers, falsework and other appliances is frequently as difficult as the manufacture of the bridges themselves and their erection is often carried on in countries remote from sources of supply. Schools and colleges are equipped and conducted for training engineers, chemists and other technical men, and publishers and printers are employed in supplying technical literature. The effect, therefore, of bridge building, like other great enterprises, is felt throughout the whole world and nearly all people are in one way or another benefited. An industry involving so great capital investment and the labor of so many persons is therefore deserving of the most careful study. If the design is faulty, the money invested and the labor spent, both directly or indirectly, in allied industries, is wasted. This is well illustrated ii?

the ill-fated Quebec bridge, which fell before completion, and also in many others which are failures in other ways. Ugly bridges in beautiful surroundings are artistically unsatisfactory, and those which must too often be renewed are failures financially because of the selection of a wrong material for the duties imposed upon them. The need for greater attention to design is therefore evident, as upon it the whole success or failure of the structure depends.

No project is now too great for investigation. Designs have been made for a bridge twenty-one miles long, to cross the English Channel (Fig. 3), and though financially impractical, one

Fig. 3 of America's leading engineers has declared that one on floating piers could be built across the Atlantic, giving railroad communication between the two continents. As far as engineering is concerned, almost any project is possible if enough money is available.

Practical span limits in steel have now been reached, but the investigations of metallurgists and chemists may lead to the production of new building material by the use of which greater lengths will be possible. Long spans are in many cases an evident advantage. The busy water courses of large cities like London and Paris are most useful when unobstructed with piers»

IMPORTANCE OF BRIDGES and since larger spans have become possible, many old bridges with shorter ones have been replaced by others with longer openings. The present London bridge with four river piers replaced one (Fig. 4) which had nineteen piers, obstructing two-thirds of the river channel, and the Seine at Paris and Tiber at Rome are now crossed with single spans. The bridges of New York

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Fia and some other cities are far more conspicuous, especially from the river, than all their great buildings, which have cost untold millions.

RELATION OF BRIDGES TO HUMAN PROGRESS

Rivers have often been a dividing line between races and nations. Before the days of bridges, each tribe was content with the products of its own territory, but as a desire grew to enjoy the good things of adjoining countries, the rivers and territorial boundaries were crossed, and adjoining tribes exchanged their commodities with each other. Such intercommunication, from which the benefit was great and evident, naturally developed and increased. The founding and building of empires has always been dependent on roads and bridges. The Romans saw that the requisites for a great nation were a fertile soil, natural resources and abundant means of transportation, and the excellence of the Roman roads has scarcely been surpassed. Their roads and bridges (Fig. 5*) have endured for

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Fis more than twenty centuries, and are used by the present generations. Without roads, the settlement of a country is impossible. In the opening up and development of the United States, Canada, Africa and Australia, an extensive policy of road construction has been carried out, often at the expense of the national government, for when roads are built, the settlement of the country and the growth of towns and cities is assured.

The building of roads and bridges has therefore been the greatest factor in the development of nations and empires, and the condition of these utilities has always been a measure of their civilization and greatness. In the middle of the eighteenth century, France realized its need, and created a Department of Bridges and Highways in the national government, and fifty years later England constructed more than a thousand

es of highway under the able direction of Thomas Telford.

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* From Concrete Kridges and Culverts. By H. G. Tyrrell.

IMPORTANCE OF BRIDGES 15

Few works are of greater service to mankind. Commerce is created and the products of civilization can be distributed for the benefit of all. Workers in crowded metropoHtan quarters are permitted to live in rural or suburban districts amid more healthful surroundings; sickness is avoided and the lives of workmen and their families are lengthened and made more secure. The building of highways and railroads opens up new tracts and increases land values enough many times to repay their cost.