A treatise on roads and pavements

Book I ("^ COPYRIGHT DEPOSm ill

WORKS OF

PROF. IRA O. BAKER

PUBLISHED BY

JOHN WILEY & SONS, Inc.

A Treatise on Masonfy Construction.

Materials and Methods of Testing Strength, etc.; Combinations of Materials— Composition, etc.; Foundations— Bearing Power of Soils, etc.; Masonry Structure— Dams, Retaining Walls, Abutments, Piers, Culverts, Vousoir Arches, Elastic Arches. Tenth Edition, Re-written and Enlarged. 8vo, 745 pages, 244 figures, cloth, $5.00.

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A Treatise on Roads and Pavements.

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A TREATISE

ON

ROADS AND PAVEMENTS

BY

IRA OSBORN BAKER, C.E., D. Eng'g

Professor of Civil Engineering, TJnimrsity of Illinois; Author of Masonry Construction, Engineer's Surveying Instruments; Member of American Society of Civil Engineers, Western Society of Engineers, Society for Promotion of Engineering Education

THIRD EDITION

RE-WRITTEN AND ENLARGED

FIRST IMPRESSION

JOHN WILEY & SONS, Inc,

London; CHAPMAN & HALL, Limited

BY

IRA OSBORN BAKER

, PRE88 OP

BRAUNWORTH & CO.

BOOK MANUFACTURERS

BROOKLYN. N. Y.

Preface

FIRST EDITION

NsT The object of this book is to give a discussion from the point of

view of an engineer of the principles involved in the construction of country roads and of city pavements. The attempt has been made to show that the science of road making and maintenance is based upon well-established elementary principles, and that the art depends upon correct reasoning from the principles rather than in attempting to follow rules or methods of construction. In some cases practical experience has not yet determined the best method of procedure, and in these cases the conflicting views with the reasons for each are fully stated.

Considerable space has been given to the economics and location of country roads and to the construction and maintenance of earth roads, since such roads constitute more than ninety-five per cent of the mileage of the public highways and are greatly in need of careful consideration. It is frequently claimed by engineers that the pubhc would be benefited by placing the care of the roads in the hands of engineers; but there is no evidence that any considerable number of engineers comprehend either the principles of road making necessary for the improvement and maintenance of our country roads, or the economic limitations and political d fficulties of the problem. The first five chapters of this book are offered as a contribution to this phase of the good-road problem.

The remainder of the book, the portion that considers roads having permanently hard surfaces, which may not unfittingly be said to relate to urban and suburban roads, is based chiefly upon American experience, because the principles of road making worked out in this country are probably best suited to American conditions, and also because in most particulars American roads and pavements are superior to any other in the world. Some countries have more hard roads than this, because of a difference in conditions; but in no country does the quality of such roads average

IV PREFACE — FIRST EDITION better than in this. In some foreign cities the pavements seem to be better cared for than in this country, owing chiefly to different controlUng conditions; but the principles of construction employed here are equal to the best. Notwithstanding the general excellence of the best American practice in constructing hard roads and pavements, there is still room for improvement in adapting the particular form of construction to the local conditions and also in preserving the surface from ruthless destruction. These two phases of the subject have been emphasized in the proper places in this volume. Throughout the attempt has been to state fully and clearly the fundamental principles of the construction and maintenance of roads and pavements.

In the preparation of the book the endeavor has been to observe a logical order and a due proportion between the different parts; and great care has been taken in classifying and arranging the matter. It will be helpful to the reader to notice that the volume is divided successively into parts, chapters, articles, sections having smallcapital black-face side-heads, sections having lower-case black-face side-heads, sections having lower-case itahc side-heads, and sections having simply the serial number. In some cases the major subdivisions of the sections are indicated by small numerals. The constant aim has been to present the subject clearly and concisely.

Every precaution has been taken to present the work in a form for convenient practical use and ready reference. Numerous cross references are given by section number; and whenever a table or a figure is mentioned, the citation is accompanied by the number of the page on which it may be found. The table of contents shows the general scope of the book; the running title assists in finding the different parts; and a very full analytical index makes everything in the book easy of access.

The author will esteem it n favor if any errors that may be found are at once brought to his notice.

I. O. B.

Champaign, III., November 27, 1902.

PREFACE

THIRD EDITION

The numerous changes in methods of road and pavement construction have made necessary a radical revision of this volume. Five years ago, before many of the changes had become well estabhshed, a second edition was issued containing a supplementary chapter which briefly treated some of the new forms of construction. The present edition has been thoroughly revised and entirely re-written. Five chapters of minor importance have been dropped to make room for an equal number of new ones. The number of illustrations has been greatly increased. No pains have been spared to bring the book up to date and to fully present the best modern practice.

Attention has been given to materials and forms of construction that affect the quality and cost of the road and pavement, rather than to the machines employed and the methods of doing the work. In other words, the book is intended more for the one who designs and inspects the road or pavement than for the contractor who constructs it. In recent years there have been developed a number of machines for doing road work and for handling road-building and paving materials that have greatly reduced the cost of road and pavement construction; but to have included an adequate discussion of such appliances and of modern methods of operation and organization would have greatly increased the size of the book.

Photographs from which illustrations have been made were obtained from the following:

Austin Manufacturing Co., Chicago, 111.

Baker Manufacturing Co., Springfield, 111.

Barber Asphalt Paving Co., Philadelphia, Pa.

Barrett Manufacturing Co., New York City, N. Y.

Cressy Contracting Co., Boston, Mass.

Granite Paving Block Manufacturing Association of the U. S., Boston, Mass,

Illinois Paving Brick Publicity Bureau, Chicago, 111.

Illinois State Highway Department, Springfield, 111.

VI PREFACE THIRD EDITION

Metropolitan Paving Brick Co., Canton, Ohio.

National Paving Brick Manufacturers Association, Cleveland, O.

Portland Cement Association, Chicago, 111.

Standard Oil Co., New York City, N. Y.

U. S. Office of Public Roads and Rural Engineering, Washington, D. C.

Mr. Walter Buehler, Chicago, 111.

Mr. John S. Crandell, New York City, N. Y.

Mr. Harlan H. Edwards, Danville, 111.

Mr. Richard H. Gillespie, Chief Engineer of Streets, Bronx, New York City.

The following persons have generously given valuable suggestions on the subject stated.

Mr. Arthur N. Johnson, Chicago, Concrete Roads. Mr. Walter Buehler, Chicago, Wood-block Pavements. Mr. Philip P. Sharpies, New York City, Bituminous Materials. Mr. John W. Stipes, Champaign, 111., many matters. Mr. D. T. Pierce, Philadelphia, Sheet Asphalt Pavements. Mr. W. C. Perkins, Conneaut, Ohio, Brick Pavements.

Mr. George N. Norton, Buffalo, N. Y., Cost of Maintenance of Sheet- Asphalt Pavements.

Mr. Walter L. Weeden, Boston, Granite Block Pavements.

Valuable data were received from many, which are specifically acknowledged in the text.

To all of these the author gratefully acknowledges his obUgations.

Urbana, Illinois, January 8, 1918.

PART I. COUNTRY ROADS Page

Introduction 1

Chapter I. Road Economics And Road Administration

Art. 1. Road Economics. Advantages of Good Roads. Cost of Wagon Transportation. Financial Value of Road Improvements. Tractive Resistance. Power of Horse. Travel Census. Weight and Width of Vehicles 3

Art. 2. Road Administration. Administrative Unit. State Aid. National Aid. Classification of Roads. Road Taxes 31

CHAPTER 11. ROAD LOCATION

Elements Involved. Distance. Grade. Rise and Fall. Curves. Width. Cross Section. Placing the Line. Establishing Grade. Example of Re-location 41

Chapter III. Earth Roads

Art. 1. Construction. Width. Cross Section. Grades. Drainage. Excavation and Embankment. Improving Old Roads. Road Building Machinery. Cost of Earthwork. Bridges. Waterways. Culverts. Retaining Walls. Guard Rails. Guide Posts. Artistic Treatment 70

Art. 2. Maintenance. Destructive Agents. Care of Surface: Road Drags and Rules for Using; Scraping Grader and Rules for Using; VRoad- Leveler. Care of Side Ditches. Care of Roadside. Obstruction by Snow. Systems of Maintenance. Expenditures for Maintenance 115

Art. 3. Surface Oiling. Preventing Dust. Effect of Oiling on Maintenance. Preparing Surface. The Oil. Applying the Oil. Cost .... 133

Chapter IV. Sand And Sand-clay Roads

Art. 1. Sand Roads. Drainage. Grading. Shade. Hardening the Surface 139

Art. 2. Sand-clay Roads. The Design. Natural Mixture of Sand and Clay. Sand on Clay Subgrade. Clay on Sand Subgrade. Cost.

vii

Vlll CONTENTS

Chapter V. Gravel Roads Page

Art. 1. The Gravel. Requisites for Road Gravel. Distribution of Gravel. Characteristics of Different Gravels 150

Art. 2. Construction. Drainage. Width. Maximum Grade. Crown. Forms of Construction: Surface Construction; Trench Construction. Bottom Course. Screening the Gravel. Hauling the Gravel. Measuring the Gravel. Cost. Economic Value of Gravel Surface. Specifications. . . . 165

Art. 3. Maintenance. Destructive Agents. Method of Maintenance. Cost 178

Art. 4. Dust Palliatives. Dust Preventives: Fresh Water, Sea Water, Deliquescent Salts, Proprietary Compounds, Sprinkling with Oil. . . . 181

CHAPTER VI. WATER-BOUND MACADAM ROADS History 185

Art. 1. The Stone. Requisites for Road Stone. Methods of Testing Stone 186

Art. 2. Construction. Forms of Construction. Width. Crown. Thickness. Cross Section. Permissible Grades. Preparing Subgrade. Crushing the Stone. Spreading the Stone. Road Rollers. Rolling the Stone. Binding the Stone. Cost of Construction. Specifications 189

Art. 3. Maintenance. Leveling. Ruts. Patching. Rolling. Sprinkling. Cost 223

Chapter VII. Portland-cement Concrete Roads

Definitions. History 227

Art. 1. The Materials. Cement. Fine Aggregate. Coarse Aggregate. Theory of Proportions. Methods of Proportioning. Data for Estimates 227

Art. 2. The Construction. Drainage. Preparing the Subgrade. One- vs. Two-course Pavements. Cross Section. Maximum Grade. Width. Thickness. Crown. Side-forms. The Concrete: proportions, mixing, consistency, placing, striking, finishing, curing, protecting. Contraction Joints. Reinforcement. Shoulders. Curbs. Cost of Concrete Roads. Characteristics of Concrete Roads. Concrete Street Pavements. . 238

Art. 3. Maintenance. Character of Work Required. Cost of Maintenance 264

CHAPTER VIII. BITUMINOUS ROAD MATERIALS Definitions 267

Art. 1. Asphalt. Definitions. Characteristics of Asphalt. Sources of Asphalt. Specifications for Asphalt: for Bituminous Surfaces, Binder for Bituminous Macadam, Binder for Bituminous Coiicrete, Sheet Asphalt,

Filler for Block Asphalt. Cost 267

Art. 2. Petroleum. Classification. Methods of Refining. Shipping. Asphaltic Content of Road Oils. Specifications for Oil: for Park Drives, Earth Roads, Gravel Roads, Macadam Roads. Cost 283

CONTENTS IX

PAGE

Art. 3. Tar. Definitions. Characteristics of Tar. Specifications: for Bituminous Surface, Bituminous Macadam, Bituminous Concrete, Joint Filler for Block Pavements. Cost 289

CHAPTER IX. BITUMINOUS SURFACES FOR ROADS Kinds of Bituminous Surfaces 296

Art. 1. Protective Coating. Bituminous Material 297

Art. 2. Bituminous Carpets. Bituminous Material. Cleaning Road

Surface. Applying Bituminous Material. Value of Bituminous Carpets.

Maintenance. Cost 298

i

Chapter X. Bituminous Macadam And Bituminous Con- Crete Roads

Art. 1. Bituminous Macadam Roads. Foundation. Maximum Grade. Crown. Wearing Course. Bituminous Binder. Tar-sand Macadam. Characteristics of Bituminous Macadam. Costs. Maintenance 306

Art. 2. Bituminous Concrete Roads. The Aggregate. The Binder. Mixing. Laying. Seal Coat. Cost. Comparison of Bituminous Macadam and Bituminous Concrete 312

Chapter XV. Pavement Foundations Page

Art. 1. Preparation of Subgrade. Drainage. Rolling the Subgrade. Filling Trenches 392

Art. 2. The Foundation. Portland-Cement Concrete: Thickness, Proportions, Mixing and Placing, Finishing, Curing. Cost. Old Macadam. Bituminous Concrete Foundation 399

Art. 3. Foundations for Street-railway Tracks. Foundation. Ties. Rails. Paving 407

Chapter XVI. Asphalt Pavements

Art. 1. Sheet Asphalt Pavements. Classification. History. Foundation: portland-cement concrete, bituminous concrete, other forms. Binder Course: open, closed; cement; bitumen in binder; mixing; laying; thickness. Wearing Coat: sand; filler; cement; bitumen in wearing coat ; mixing; laying; rolling; thickness. Asphalt Adjacent to Tracks. Causes of Failure. Methods of Repairing. Cost of Construction. Cost of Maintenance. Maximum Grade. Crown. Merits and Defects. Specifications 411

Art. 2. Asphalt Concrete Pavements. Definitions: Bitulithic, Warrenite, Amiesite, Topeka mixture, stone-filled sheet-asphalt, asphalt-concrete pavement. Mixing and Laying. Cost. Merits and Defects. Specifications 461

Art. 3. Rock Asphalt Pavements. Construction 469

Art. 4. Asphalt Block Pavements. The Blocks. Cost. Merits and Defects 470

Chapter XVII. Brick Pavements

Art. 1. The Brick. The Clay. Manufacture of the Brick. Kinds of Brick. Size. Testing the Brick. Service Tests 474

Art. 2. Construction. Foundation. Bedding Course* sand cement-sand, mortar. Laying the Brick. Joint Filler: sand, hydraulic grout, bituminous cement, tar-sand. Expansion Joints. Comparisor of Types. Brick Adjacent to Track. Maximum Grade. Brick Streets. Brick Roads. Cost. Merits and Defects. Specifications 503

Art. 3. Maintenance. Repairs: soft brick, shrinkage of sand cushion, settlement of foundation, settlement of trench, defective grouting, bulges, re-laying pavement, cracks. Re-surfacing: asphalt top, tar top, turning the brick, monolithic brick top. Cost of maintenance 552

Chapter XVIII. Stone-block Pavements

Nomenclature : Roman roads, cobble-stone, Belgian-block, oblong-block, durax pavements 566

Art. 1. The Stone: granite, Medina sandstone, Potsdam sandstone, Sioux Falls quartzite. Kettle River sandstone, limestone 569

CONTENTS XI

PACE

Art. 2. Construction. Foundation. Bedding Course: sand, mortar. The Blocks: dressing, re-cutting, size, measuring. Setting. Ramming. Filling Joints. Expansion Joints. Paving Adjacent to Track. Maximum Grade. Merits and Defects. Durax Pavement. Cost : the blocks, granite-block, Medina-sandstone block, and durax pavements 572

Art. 3. Maintenance. Re-laying. Re-filHng Joints. Spalling Joints. Raising Low Blocks. Settlement of Foundation. Settlement of Trench. . . . 597

Chapter XIX. Wood-block Pavements

Kinds of Wood-block Pavements. History 601

Art. 1 . Materials and Treatment. The Timber. Causes of Decay. Preservative. Treatment 603

Art. 2. Construction. Bedding Course: sand, cement-sand, mortar, bituminous cement. Laying the Blocks. Joint Filler: sand, tar pitch. Open-joint Construction. Expansion Joints. Cost. Merits and Defects. Specifications 612

Art. 3. Maintenance. Removing Poor Blocks. Raising Low Spots. Re-laying over Trenches. Lowering Bulges. Bleeding. Cost of Maintenance 628

CHAPTER XX. SELECTING THE BEST PAVEMENT Kinds of Pavements 633

Art. 1. The Data for the Problem. Durability. Requirements of the Ideal Pavement: cost of construction, cost of maintenance, tractive resistance, slipperiness, ease of cleaning, noiselessness, healthfulness, freedom

from dust and mud, temperature 635

Art. 2. The Solution of the Problem. Economic Solution. Non-economic Solution , 651

ROADS AND PAVEMENTS

Introduction

The problems involved in the construction and maintenance of rural highways differ materially from those which are encountered in the improvement and care of city streets, and therefore this discussion of the subject of Roads and Pavements will be divided into Part I, Country Roads, and Part II, City Pavements. In each division of the subject certain general principles will first be considered, and the further discussion will be divided according to the several materials in use for road surfaces. It will not always be possible to keep the several portions entirely distinct, but a knowledge of the intention in this respect will make it easier to understand the method of presentation or to turn readily to the discussion of any particular phase of the subject.

The classification of road surfaces into country Roads and City Pavements is partly according to the most general use of each, and partly according to the elaborateness of the construction. According to the somewhat loose classification here adopted road surfaces for country roads consist of two parts, subgrade and wearing coat; while city pavements consist of four parts, subgrade, foundation, a binder or cushion course, and a wearing coat.

PART I COUNTRY ROADS

Part I will include matters relating to earth, sand and sand-clay, gravel, water-bound macadam, bituminous macadam, and concrete roads in rural districts, although some of the discussion is also applicable to these road surfaces when employed in city streets.

Chapter I Road Economics And Road Administration

1. Advantages of Good Roads. Good roads are so important to the financial, social and educational well-being of a rural community that no enumeration of their advantages is likely to include all the benefits; but a brief consideration of some of the chief advantages of good roads will be of value in determining the amount of money that may justifiably be expended to secure road improvement and in deciding who should in equity bear this expense. The principal advantages of good roads, i. e., of permanently hard ones, are as follows :

1. Good roads decrease the cost of transportation, — at some seasons of the year considerably, but at others very little. This item will be considered more fully later (see § 4-9).

2. Good roads make the marketing of crops easier. This advantage results in extending the area devoted to the cultivation of fruits and vegetables, and is most effective in the vicinity of a large city.

3. Good roads give a wider choice of time for the marketing of crops. In some instances good roads permit the marketing of crops when the labor of production is not pressing; but this advantage accrues only to the producers of imperishable crops, and is not of great importance since the labor required to market the product is small in comparison with that of production.

4. Good roads permit the marketing to be done when prices are most favorable. This advantage is more important with perishable than with imperishable products. As far as perishable products are concerned, this advantage is virtually included in paragraph 2 above. As far as imperishable products are concerned, this advantage is important only near a large city, i. e., where the producer hauls to the market. Prices of staple farm products (not garden products) are not much affected by roads, since the condition of the roads is local while prices are governed by world-wide conditions. Writers on good-road economics usually greatly overestimate this advantage as far as the ordinary producer of imperishable products is concerned. If this advantage were anything like as great as is frequently claimed, producers would store such products at the local shipping point, or in the great city, or at the port of export, awaiting a favorable price. Such storage would also permit the delivery at a time when other work was least pressing. The expense of storage at the local shipping point is a small per cent of the value of the product. It is frequently, but erroneously, claimed that hard roads would save the Illinois farmer 3 to 5 cents per bushel — an amount 10 to 15 times the cost of storage. Since producers do not so store their products, it is safe to assume that this advantage of good roads as a rule, is not very great. The present method of doing business makes this advantage comparatively unimportant.

5. Good roads give a wider choice of the market place. This advantage affects perishable products chiefly, and for geographical reasons is, as a rule, not very great.

6. Good roads tend to equahze the produce market between different weather conditions. In the absence of railroad transportation and cold storage, this advantage might be of considerable local importance; but under ordinary conditions it is comparatively unimportant.

7. Good roads tend to equahze railroad traffic between the different seasons of the year. Impassable wagon roads over any considerable area materially decrease the amount of agricultural products to be transported by railroads, and a return of good roads will for a time congest the railroad transportation facilities. The effect of good roads in equahzing railroad transportation is partially neutralized by the fact that agricultural products are only one of many classes of commodities transported by the railroads; and also by the fact that most railroads transport agricultural products originating over a considerable area, and bad wagon roads are not likely to occur over all the contributory area at the same time; and further by the fact that the storage capacity of warehouses helps to equalize the traffic.

8. Good roads tend to equalize mercantile business between different seasons of the year. Merchants having a considerable rural custom could do business more economically if the trade were . distributed uniformly throughout the yeal*. However, the succession of good and bad wagon roads is only one cause of the unequal distribution of rural patronage.

9. Good roads permit more easy intercourse between the members of rural communities, and also between rural and urban populations. This is an important benefit, particularly under a democratic form of government.

10. Good roads facilitate the consolidation of rural schools, and thereby increase their economy and efficiency. This is an important matter to coming generations.

11. Good roads facilitate rural mail delivery, and thereby tend to improve the social and intellectual condition of the rural population.

12. Good roads sometimes change rural into suburban property.

13. Good roads are a material factor in stimulating tourist travel and making rural communities attractive to vacation residents.

2. It is customary to include the increase in the price of farming land as one of the benefits of good roads; but the increase in price of land is simply the measure of the value of all the above advantages, and hence should not be included.

3. Notice that the first eight advantages mentioned above relate to the financial benefits of good roads, and the last four to the social benefits. In the past writers upon good-road economics have given much attention to the supposed financial benefit of hard roads and little or none to the social advantage. Any considerable expenditure for the improvement of rural highways can not be justified on financial grounds alone (§ 12). Good roads are desirable for the same reason that a man buys an automobile or builds a fine house, i. e., because they are a comfort and a pleasure. Good roads should be urged principally for the same reason that good schools are maintained, namely, because they increase the intelligence and value of the citizen to society.

4. COST OF Wagon transportation. The chief financial advantage of hard roads is the decreased cost of transportation. It is proposed to inquire briefly concerning the cost of wagon transportation with a view of determining the proportion of this cost that may be saved by road improvement.

In this connection, a distinction must be made between the cost to those whose chief business is to sell transportation, and the cost to those to whom transportation is a mere incident of a business organized for some other purpose. The first class is represented by a freighter, and the second by a farmer. The former maintains his teams and wagons only to transport freight, while the latter ordinarily keeps his teams and wagons primarily for general farm work of which transportation on the roads is only a small part. In some cases the traffic to be considered is principally that by freighters, but usually the chief traffic over country roads is that connected with agricultural operations.

Again, consideration should be given only to haufing in which the load is equal to the full capacity of the team for the particular condition of the roads. A farmer may employ a two-horse team to take a bushel of potatoes to town, or a grocery wagon may make a trip to deliver a pound of cheese; but the partial load is entirely independent of the condition of the roads.

Further, it is necessary to notice that only the rate for full loads should be considered. If a number of packages are carried in the same load for different parties, part of the charge is to cover the cost of collection, distribution, possible partial loads, etc.; and therefore only part of the charge is for transportation proper.

5. Cost to Freighters. The cost will vary greatly with the conditions of the service, i. e., with the character of the road surface, the average grade of the road, the maximum grade, return load, etc.

Except in rare cases, the cost per ton-mile for loads one way upon earth roads will not be more than 25 cents, and ordinarily it will not be more than 15 to 20 cents;* while with easy grades and favorable road surface it may be as low as 10 to 15 cents, and with long hauls, return loads, and favorable road surface, it may be 8 to 10 cents. When the last price is obtained there is little need or opportunity for road improvement.

6. Cost to Farmers. In this division of the subject, a distinction should be made between producers of perishable products and

* See "Cost of Wagon Transportation," by the author, in Proceedings of Illinois Society of Engineers, Vol. 16 (1901), p. 36-44; full abstract of the same in Engineering News, Vol. 45 (1901), p. 86.

producers of non-perishable products. The first class is represented by gardeners, dairymen, fruit-growers, etc.; and the second, by producers of hay, grain, cotton, etc.

The cost of transportation is much greater for perishable than for non-perishable products. In the first place, the marketing of perishable products is an important factor in comparison with the cost of production, and frequently necessitates an independent transportation department; while the labor of marketing non-perishable products is comparatively small — particularly as in most localities where there is much of this class of produce, the distance from the farm to the railroad station is short. Further, perishable products must go to market whatever the condition of the roads, while non-perishable ones can wait for comparatively favorable conditions; and finally, the former frequently go to market in partial loads, and the second usually in full loads. Except in comparatively limited districts, non-perishable products make up the bulk of the traffic on the country roads. According to the U. S. Census of 1890, the gardeners, fruit-growers, dairymen, vine-growers, florists, and nurserymen constitute only 1.8 per cent of the so-called farming class.

7. The cost of transporting perishable products is probably greater than that for any other class of traffic over the country roads; but as it is next to impossible to secure any reliable data no attempt will be made to present any general conclusions. For several reasons, this traffic will usually justify larger expense for road improvement than any other.

The cost of transportation to farmers proper, i. e., producers of non-perishable products, depends chiefly upon the condition of the road surface and upon the demands of general farm work. Loam or clay roads are reasonably good when dry, and are therefore at least passable most of the year; while sand roads are at their worst when dry, and are therefore in their worst condition during the greater part of the year. Fortunately sand roads are less common, the country over, than clay or loam roads. In the crop season, with a little choice as to the time of doing the work the cost on fairly level loam or clay roads is probably not more than 10 to 12 cents per ton-mile; and when farm work is not pressing, the cost is not more than 8 to 10 cents per ton-mile.*

* See " Cost of Wagon Transportation," by the author, in Proceedings of Illinois Society of Engineers, Vol. 16 (1901), p. 36-44; full abstiact of the same in Engineeiing News, Vol. 45 (1901), p. 86.

ROAD ECONOMICS AND ROAD ADMINISTRATION

Chap. I

8. A Conflicting View. In current literature on road economics, the claim is frequently made that the cost of wagon transportation to the farmer is considerably more than stated in § 7. Apparently most of these claims are ba*sed, either directly or indirectly, upon data published in Circular 19 of the Road Inquiry Office of the United States Department of Agriculture under date of April 4, 1896. Table 1 is a brief summary from that circular^

The conclusions of this circular halve been so widely quoted and so generally accepted as to justify a brief consideration. In former editions of this book, these conclusions were somewhat carefully considered, and the following is a brief summary of that investigation.

TABLE 1 Alleqed Cost op Wagon Transportation

Ref.

No.

Locality.

Average

Distance

Hauled,

Miles.

Average Load

Hauled, Tons.

Average

Coi?t per

Ton-mile,

Cents.

Total Cost

from Farm

to Market,

per Ton.

Eastern States.

5.9

6.9 8.8

12.6 8.8

23.3

1.108

27 31 25

22 22

$1 89

Northern States

1 86

Middle-Southern States

Cotton States

2.72 3.05

Prairie States.

1 94

Pacific Coast and Mountain. . . .

Whole United States

5.12

12.1

1.001

3.02

Circular 19 concludes that 313,349,227 tons were hauled over the highways of the United States in 1895 at a cost of $3.02 per ton-mile, or a total cost of $946,314,665.54; and that the annual cost of transporting the crops of the United States to market was 26.6 per cent of the price of the crops at the market. These conclusions are greatly in error chiefly for the following reasons:

1. The investigation was not very elaborate, since replies were received from only one county in thirty.

2. The average distance hauled seems to be about twice too great.

3. The value for the average load hauled is approximately twice too great. The mean between the maximum and the minimum load may be one ton; but the great bulk of teaming is done when the roads are at least in fair condition, when the load is considerably more than one ton. The author has examined the records of several grain buyers in central Ilhnois, where at times the roads are as bad as anywhere, and finds that the average load is nearly a ton and a half. Statistics for marketing over 300,000 bushels of corn in Illinois gives the average load as almost exactly 2 tons.

4. The cost per ton-mile indicates that this value was obtained by assuming that the wages of wagon, team, and driver are 35 cents per hour; that the team travels 3 miles per hour; and that the team hauls a load only one way. The price per hour for a team is too great, since the cost per day as reported by 316 farmers in 76 counties in Illinois varied during crop time from $1.40 to $2.74, the average being only $2.13, or say 21 cents per hour.

5. No account was taken of the relative amounts of traffic in the several states.