Owing to the diversity of opinion existing among railroad men as to the proper scope of a book on railroad economics, a word of introduction is necessary. Railroad economics, in its broadest sense, covers the entire subject of railroad engineering, from the most simple feature of railroad surveying to the weightiest questions of railroad practice or legislation which could be brought before the Interstate Commerce Commission, Congress, or the United States Supreme Court. While it is of course desirable that an engineer should have as broad a knowledge as possible of every phase of railroad management and legislation, it should not be forgotten that his primary work is that of construction, maintenance, and operation. If the railroad engineer should develop into the railroad president, the larger questions must be answered, but even in such a case an encyclopedia of railroad science would not cover the ground with which he should be familiar.

It is assumed that those who read or study this book are already familiar with the mechanical processes used in railroad surveying and construction; that they know how to survey a line (when the economic questions of its location have been decided), and how to build a line as thus laid out. Of course many of the simpler economic principles will have been included in any good course in surveying and construction. But such courses do not usually include an exhaustive exposition of the reasons why certain grades should be adopted, or why a certain large expenditure for a tunnel, bridge, or other special construction may (or may not) be justifiable. The justification of improvements by changes in alinement also comes within the scope of the engineer. The constructing engineer should also know enough of the work of opera-tion to understand the effect on operation of constructive details. This requires a knowledge of operating expenses, locomotive and car construction, train-resistance, and the operation of heavy trains on grades. Even then the constructive engineer is not equipped for his work until he has dipped into law and finance - until he understands the legal method of organization and the methods of the world of railroad finance.

Rising still higher, the railroad man is sometimes confronted with an apparent conflict between a policy which would best serve the public, and a policy which would afford greater immediate profit to the stockholders. Probably such conflicts are more apparent than real. History has invariably shown that the prosperity of a railroad is closely bound up with that of the community which it serves, and that in the long run the interests of the stockholders are best promoted by policies which give the best possible service to the public.

This book is therefore written from the standpoint of the constructing or operating engineer. The railroad lawyer or legislator would find little or nothing in it which he can use, and much in which he is not interested. Even the professor of social economics will find that it is written from the technical standpoint rather than from the social viewpoint, and yet (as before mentioned) it will be emphasized that the best social standpoint will also prove to be the best technical standpoint.

The practicable size of this book has also been considered. An adequate discussion of railroad legislation alone would more than fill a book of this size. Therefore legislation and kindred subjects are only considered very briefly, and almost exclusively as they affect questions which must be answered by a railroad engineer.

The author wishes to acknowledge his indebtedness to many engineers throughout the country who have furnished him with some very valuable technical information. The sources of such information have each been indicated during its discussion.

Those familiar with recent railroad literature, especially the books dealing with railroad legislation, the regulation of rates, etc., will appreciate the author's indebtedness to some of them. The chapters of this book dealing with kindred subjects attempt to give an abridged outline of some of the most salient features of these valuable additions to railroad science. For more complete discussions the student should read the following: "Railway Legislation in the United States," by Dr. B. H. Meyer; "Restrictive Railway Legislation," by H. S. Haines; "American Railway Transportation," by E. R. Johnson; "The Elements of Railway Economics," by W. M. Acworth; "Railroad Transportation," by A. T. Hadley; and "American Railroad Rates," by W.C. Noyes.

The preparation of the second edition has required a very extensive revision and even the rewriting of several sections and the compilation of revised tables in order to make the computations correspond with the classification of operating expenses now used by the Interstate Commerce Commission. But the general principles used are the same as those laid down in the first edition.