A practical treatise on roads, streets, and pavements

Front matter

THE GIFT OF

6896-3

Cornell University Library

Prefatory Note

In the preparation of the following pages a few leading objects have been kept in view by the author.

First. To give, witliin the compass of one small volume, sudi descriptions of the various methods of locating country roads, and of constructing the road and street coverings in more or less common use at the. present day, as will render the essential details of those methods, as ■well as certain improvements thereon of which many of them are believed to be susceptible, familiar to any intelligent non-professional reader.

Second. To make such practical suggestions with respect to the selection and application of materials, more especially tliose, with the properties and uses of which builders are presumed to be the least acquainted, as seem needful in order to develop their greatest practical wortli, and realize their greatest endurance.

Third. To institute a just and discriminating comparison of the respective merits of the several street pavements now competing for popular I'ccognition and favor, under the varying conditions of traffic, climate, and locality, to which they iire commonly subjected.

Q. A. O.

Xew York, March 1, 1870.

Table Of Contents

CIIAPTEE I.

LOCATION AND GRADES OF COUNTKY EOADS.

TAGE

CHAPTER II. EAETHWOKK, DEAINAGB AND TRANSVERSE FORil OF COUNTRY ROADS

Excavations and embankments. — Computations of same. — The lead. — Increase in volume, or "growth" of excavated earth. — Moving earth. — Completed map and specifications. — Fixing the line on the ground. — Side slopes in cuttings. — Their treatment when infested with springs.— The drains necessary. — Other precautions to insure stability. — Cuttings through rock. — The formation of embankments. — Embankment slopes. — Methods of their protection. — Hill side roads. — Sustaining ■walls for same. — Roadg along rocky hill sidefi. — lloads over

COJfTENTS.

PAOE

marshy and swampy grounds. — Same over deep marshes. — Uoads over tidal marshes.— Protecting and draining same by dikes and sluice gates. — Application of this method to Jersey Flats. — Side-cuttings. — Spoil-banks.— Side drains. — Cross drains.- Cost of stone, brick and tile drains.— Surface drains. —Covered side drains, and silt basins.— Culverts of wood, concrete, etc. — Width of main, cross and branch roads; of the French roads ; of the Cumberland road.-rTransverse form of roads. — Catcli waters. — Tools and implements 35 to 75

CHAPTEE III.

BOAD COVEKIXGS.

The object of road coverings. — Best ma;,erial for same. — The basaltic, doleritic and other trap rock. — Other materials. — Earth roads. — Construction, maintenance, and repairs of same. — Corduroy Eoads. — JPlank Roads. — Advantages and defects of same. — Gravel roads. — Directions for their construction. — Screening and applying the gravel. — Road rollers. — Good gravel roads. — Inferior gravel roads. — Macadam roads. — Practice of the English and the French constructors. — Roads of the Central Park in New York city. — Preliminary tests of stone for road coverings. — The stone crusher. — Thickness of the road covering. — Macadam's practice. — Applying the broken stone. — The " wings " of roads. — Telford roads. — The Telford sub-pavement. — Same with gravel and broken stone on top. — Rubble stone sub-foundation, and Telford pavement. • — Same without the Telford pavement. — Concrete foundation with gravel and broken stone on top. — Foundation of rubble stone and concrete. — Shell roads. — Charcoal roads 76 to 108

CHAPTEE IV.

MAINTEJfANCE AND EEPAIIIS OF EOADS.

Schemes for raising and applying the funds not discussed. — Excellence of maintenance requisite from motives of economy alone. — Different conditions of the same road compared. — Relation of animal force to traflac on different roads. — Where traffic justifies the construction, it exacts the thorough maintenance of a road. — Broken stone roads are seldom well kept, up. — Method of maintenance by minute daily repairs, of roads

COXTEXTS. '

of moderate trallic. — Implements. — WliitwnrtU's machiiiB sweeper. — Street sweeper used in Xew York city. — A very soft sweeper necessary upon road coverings. — Directions for applying tlie new materials. — 'i'liick layers to be avoided. — Tlie process is properly one of constant patching. — Experience of the French Engineers. — Roads iu the Department of the Sarthe. — Lyons and Toulouse road. — Tours and Caen road. —Method of maintenance by periodical reconstruction. — Adapted to roads of large traffic. — Practical precautions necessary. — Kelaying and rolling. — Material to be sprinkled. — Determination of thickness and composition of road covering. — Relation between annual wear and average daily tonnage of roads in the Department of the Loire, and in the Arrondissement of St. Etienne. — Curves of daily tonnage and annual wear. — Ratio of wear to tonnage not constant. — Wear increases more rapidly than tonnage. — Necessity for using the best material increases with the tonnage. — Apportionment of materials. — Maintenance of gravel roads 109 to 136

CHAPTER V.

STIIEETS AND STREET PAVEMEXTS.

functions of a modern street. — Ancient sewers. — Modern sewers. — Necessity of subsoil drainage. — DifTerent methods of securing it. — The object and essential requisites of a good street pavement. — Pavement foundation of broken stone — Of sand. — Of cobble stones. — Cobble stone pavement. — Old road coverings as foundations. — Rnbhle stone pavement, as a foundation. — Concrete foundation. — Foundation of rubble stone and concrete. — Sidewalks and sidegutters. — Curb and gutter stones. — Pavement of stone blocks. — Best dimensions for the blocks. — Different methods of laying same. — Special methods on steep grades. The Guidet stone pavement. — The Russ and the Belgian pavements. — ^The Nieolson, Stowe and other wooden block pavements. — Treatment of wood to prevent decay. — Chicago wooden pavements, — Hydro-carbonized brick pavements. — Asphalt pavements. — Varieties of bitumen. — ■ Description of natural mineral tar, bituminous limestone and asphaltum. — The mineral tar, called also asphaltio cement, formed by uniting two or more bitumens. — Proper proportions of petrolene andasphaltine. — Bituminous limestone pavements. — Concrete the best foundation for same. — Old pavements for foundation under certain precautions. — Heating

8 CONTENTS.

tho asphalt or bituminons limestone.— Method of applying the same.— Importance of an even finish on surface. — Directions for making asphalt pavements, without the asphalt rock, comprising— (1) The preparation of asphaltic cement— (2) The powdered calcareous sand— (3) Mixing the cement and powder, and (4) applying the mixture by the first method. — Asphalt block pavements.— Merits and cost of asphalt pavements.— Asphalt pavements of New York city.— Comparative merits of wood, stone, and asphalt pavements as to — (1) durability- (2) iirst cost— (3) Cost of maintenance and repairs— (4) Facility of cleansing— (5) Convenience, apd (6) hygienic considerations. — General conclusions 137 to 307

CHAPTEE VI.

SIDEWALKS AND FOOTPATHS.

Concrete footpaths. — Foundation for same. — Precautions against upheaval by frost. — Proportions of ingredients. — Directions for laying. — Treatment of surface layer. — Squares or rectangles preferable to a single sheet. — The Schillinger pavement. — Deficient in compressive strength and power to resist frost. — Table of compressive strength of Portland cement and Rosendale cement Mixtures. — Beton Coignet. — Asphalt footpaths. — Their thickness. — May be made with the asphalt rock, or with bituminous mastic. — Directions for making bituminous mastic. — Extensively used on public works. — ^Method of application. — Sidewalks over street vaults. — Must be water tight. — The precautions necessary to secure that condition. — Brick footpaths. — Foundations for same. — Flagging stone footpaths. — Hudson river flagging. — Broken stone and gravel footpaths. — For parks and sidewalks of country and suburban roads. — Preimration of the bed for the material. — Tiles for sub-drainage. — Lower layer and surface layer. —Park walks.— Transverse form.— Sod-gutters and cobble stone gutters. — Drainage of an area covered by a system of walks.— Hand-made concrete.- Mill-made concrete— The cubical concrete mixer, and manner of using it 308 to 230

CHAPTER VII.

TRAMWAYS AND STREET RAILWAYS.

Comparative tractive force, on stone tramways, broken stone roads, and gravel roads.- Definition of tramway.— Adapted to

CONTEXTS. ;)

rAOl!

all kinds of vehicles. — In common use in southern Europe. — Description of tlie Italian Tramways. — Their cost of construction, durability, maintenance, and repairs. — Tramways not adapted to the crowded streets of a city. — Double track tramway, — Pavement between tlie trams. — Pavement of selected stone blocks a good substitute for a tramway. — Street railways. — liesistances to the movement of cars on good level rails. — Kule for calculating the same. — Street grades suitable for street railways. — Bleecker street and Fulton Ferry line, Kew York. — Drainage. — Construction. — Eails. — Stringers. — C'ross Ties. — Fastenings. — Pavement of horse track. — Of street on either side. — The substitution of stone and iron for timber. — Mechanical motive power for animals. — The effect of frequent startings upon the animals. — Mechanical car starters. — 'I'he Orozier car brake and starter. — The fireless locomotive. — Table of the cost of constructing, maintaining, and operating street railways in the State of New York, and in Massachusetts S.'JT to 35i

PEACTICAL TREATISE

CIIAPTEll I. ' LOCATION AND GRADES OP COUNTRY ROADS.

Considerations Governing Iiocation.

The considerations which should govern the Engineer in locating the line of an ordinary wagon road are (1) the present and prospective amount of traffic over the road ; (2) its general character, whether light or heavy ; (3) the convenience and necessities of the community tributary to the line ; and (4) tlie natural features of the country through which the road must pass. The labor of the" preliminary examination of the ground will be considerably lessened by keeping in view a few elementary jDrinciples, viz : (1) tliat the natural water courses are not only the lowest lines, but the lines of the greatest longitudinal slope in the valleys through which they flow ; (2) that the direction and position of the principal streams give also the direction and approximate position of the high ground or ridges which lie between them ; and (3) that the positions of the tributaries to the larger streams generally indicate the points of greatest depi'ossion in tlio summits of the ridges, and therefore the points at which lateral communication across the high gi-ound separating contiguous valleys could be most

readily made.

Reconnaissance .

"With the aid of an ordinary map of the country, if reasonably correct, it is entirely practicable to trace upon it ■with a suflacient degree of accuracy for the immediate object in view, not only the general directions of the ridges or highest ground, but also to locate approximately those routes most suitable for the purposes of a road across tlio hills, from one valley to another.

Being provided with the information usually supplied by maps or, in the absence of trustworthy maps, having secured that information by an instrumental examination, the topographical and other characteristic features of the ground should be carefully studied by travelling in both directions OYcr the several routes, upon any one of which the line may be located, carefully noting down for future comparison, the distinctive features of each.

Aneroid Barometer.

If the line passes over such hilly or undulating ground, that considerable differences of level are necessarily encountered in its location, A^aluable aid may be derived from a poctet Aneroid barometer. This instrument shown in section through the axis in Fig. 1, consists of a flat cylindrical box A, exhausted of air, the top of which is thin metal corrugated in concentric circles so as to render it quite elastic. As the atmospheric pressure inci-eases, the elastic top of the box is forced in or down, and as it decreases it is forced out or up. This movement of the top of the box due to changes

AXEIIOID liAIlOMKTEU.

n ill the atmospheric pressure, is conveyed by multiplying levers DE, EG, GH, and a small chain II to an index needle NN, moving over a circular scale MM, graduated to correspond with the standard mercurial barometer. The spiral spring S, by its tension raises the long arm of the lever DE, when the pressure on the top of the box is lessened, thus keeping the short arm of the lever constantly in contact with the fulcrum C. The Aneroid is used by the following rule : The sum of the readings at two stations, is to their difference, as 55,000 (or twice the height of the atmosphere in feet), is to the ele-

Fio. 1.

vation required. Thus, if the reading at the foot of a hill is 30.05, and at the top 39.44, we have the following 59.49 : 0.61:: 55,000ft. : 564ft.

By the intelligent use of this barometer, the scope of inquiry may frequently be much narrowed at the outset, and the labor and expense of the subsequent survey greatly abridged. Foj; instance, if the line of communication is to connect two valleys by crossing the high ground between them, it should be located, other things being equal, in the lowest depression of the summit. A reconnaissance with a barometer should indicate with an error not exceeding 10 to 15ft. the relative altituda of the several summit depressions,

U KOADS, STREETS, -VXD PWEMEN'TS.

iiud thercloro the best location of tlic route, so far as tlic question of grade iixes tlie location. The average of several observations with tlie barometer, is desirable.

Surveys, Map and Descriptive Memoir.

The reconnaissance having been completed, and the inquiry narrowed down by the exclusion of the least practicable routes, preliminary surveys should then be made of the several trial-lines, with a view to determine tiieir length, direction, and position, together tvitlx a longitudinal -section and numerous cross-sections of each line. All this should be done with sufficient accuracy and minuteness of detail to form the basis of comparative estimates of their practicability and cost. Money liberally spent in surveys entrusted to skillful persons, is wisely spent, and offers the surest guarantee against subsequent mistakes and errors of judgment. Its amount, at the outside, cannot exceed a very small percentage of the cost of constructing the road, while the results, judiciously employed, are sure to furnish innumerable suggestions for lessening the cost without impairing the excellence of the communication.

Map.

The data obtained from the surveys should be carefully embodied in a map, showing with considerable detail, the topography of the country embraced by the several trial-lines, the exact position of these lines, and all the longitudinal and cross-sections. The horizontal scale of the sections should be the same as that of the map, while the vertical scale should be considerably larger, in order to show clearl" all the inequalities of the ground. AVith a horizontal scale

LOCATION OF lASE. 13

of oOOft. to the iiicb, the vertical scale may be only 20ft. to the inch.

Descriptive Meznoir.

The descriptive memoir should give with minuteness all information, such as the nature of the soil, the character of the several cuttings, whether earth or rock, the kind of rock, etc., etc., that cannot be set forth on the map. The importance of carefully noting in tlie memoir, and as far as practicable upon the map also, all variations of the character of the cuttings through rock, and esjiecially of maintaining a strict distinction between cuttings in rock and cuttings in earth, will be admitted, when it is remembered that excavations in earth can be made at less than one-fourth the cost of excavations in rock.

liocation of the Line.

" In selecting among the different lines of the survey the one most suitable for a common road, the engineer is less restricted, from the nature of the conveyance used, than in any other kind of communication. The main points to which he should confine his attention are, (1) to connect the points of arrival and departure by the shortest or most direct line ; (2) to avoid all- unnecessary ascents and descents, or in other words to keep the ascents and descents within the smallest practicable limits ; (3) to adopt such slopes or gradients for the centre line of the road as the kind of conveyance used may require ; (4) to give the centre line such a position with reference to the natural surface of the ground, and the various obstacles to be overcome, that the cost of labor for excavations and embankments required by the gradients adopted, and also the cost of bridges and other accessories, shall be reduced to the smallest amount." (Prof. Mahan.)

14 ROADS, STREETS, AXD PATEIIESTS.

Except in a flat and level country, it will seldom bo practicable to adopt, for the axis of the road, the shortest line between the points of arrival and departure. Departures fj'om a straight line are determined by a variety of considerations. In crossing a dividing ridge between two valleys, we seek a depression in the summit, in order to avoid expensive cutting, or the alternative of steep or impracticable gradients ; in descending a valley longitudinally, we keep well up on the side of the hill, if necessary, to avoid bridging the ravines and secondary water-courses ; if we encounter a swamp or shallow pond, we can frequently, by turning to the right or left, entirely omit the construction of an expensive causeway or other road bed, or substitute for it a short bridge over a narrow water-course, with easy approaches on either side ; a stream may cross and then re-cross the direct line, forming an elbow which may sometimes be turned Avithout greatly augmenting the length of the road, thus avoiding the construction and maintenance of two bridges ; we may turn aside and even bridge a stream in order to get upon that slope of a valley which will give the best exposure of the road surface to sun and wind ; or we may lengthen the road for the purpose of jjrocuring better material for its construction.

Questions of Expediency to be Considered.

Not infrequently other questions not strictly within the province of the engineer claim attention to such degree that although a straight line between the two termini of the road may be the best, considerations of expediency will very properly prevent its adoption. Intermediate communities and towns contigiTOus to the line may require accommodation,

QUESTIOXS OF EXPEDIENCY. 15

jind whether such accommodation shall be afforded by hiteral branch roads, leaying the main line essentially straight, or by running the latter through the several centres of business, -will have to be determined upon principles more or less independent of the bare problem of construction and maintenance. For example take the simplest case of three towns A, B, C, Fig. 2, situated upon a uniformly level plain, where the cost of constructing and maintaining a line of communication will be di- Fig. 2.

rectly proportional to its length. Suppose tlie points of arrival and departure, A and 0, to be 130 miles apart, and that B is equi-distant from A and 0, but located 20 miles off the direct line AC. If each town sends out 20 tons of freight per day to be distributed equally (10 tons to each) between the other two towns, a simple calculation will show that with a straight road AO, between the extreme points and a perpendicular branch road B'B to the intermediate town, the daily transportation of this 30 tons of freight, will be equivalent to transporting 1 ton 5600 miles, while if one straight road be built from A to B, and another from B to C, the total carriage will be equivalent to conveying 1 ton only 5060 miles. The difference, (equal to 540 tons carried 1 mile) in favor of the lines AB, BC, over the lines AC and B'B is borne unequally by the three towns in proportion of 335 tons to B, and 102^ each to A and C. In the case stated, it is for the mutual advantage of all the three communities to locate the line from A to B and from B to 0. But the conditions would be different if the great bulk of the traffic is between the towns of A and 0. For example, if those t-owns exchange 20 tons per day with each

10 nOADS, STEEETS, AND PAVEIIEXTS.

other, aud only 2 to 3 tons ])cv day with tlie town B, then the total mileage of transportation necessary in making the interchange, setting other considerations aside, would favor the construction of a straight line AC, between the terminal towns, and a perpendicular branch line B'B to the intermediate town. But as this would require a greater length of road by 13^ miles (140 — 136^) than a continuous line ABC passing through the intermediate town, the expediency of building and maintaining upwards of 10 percent more road than is absolutely necessary to connect the three towns, presents itself as a question of some commercial importance, and before adopting the longer system, it should be made quite clear that the yearly saving in cost of transl^ortation will be more than suflScient to pay the interest on the first cost of constructing 13^ miles of road, as well as the annual expense of its maintenance. Except in extreme cases where the two towns at the ends of the line are large in comparison with the intermediate towns, it will usually be found to be most conducive to the convenience of the general public to run the line through all the principal communities, in preference to the plan of communicating with the intermediate places by branch roads, which might necessitate branch lines of wagons and coaches, connecting with those of the main line, attended by all the usual inconvenience and expense of transferring passengers and goods at the points of junction.

In the general case, however, the road will not traverse a level plain hut will cross hills, ravines, rivers, and other accidents of the ground, so that the proper solution of the problem will involve a variety of considerations, among which the engineer's ideal of a straight and level line, the

CONTOUR LIXKS. 17

wants of the communities to be accommodated, and economy in cost of construction will generally be more or less at variance.

As it should be the first business of the engineer to make himself thoroughly familiar with the character of the country adjacent to the line, for some distance on either side, all the preliminary field work should be directed to that end.

Contour Iiiaes.

In laying out important roads, and especially in locating streets in towns or thickly settled districts, where the ques- ,tions of gradient, drainage, sewerage, and water supply assume special importance, it Avould be well to place tlie contour lines, or curves of uniform level, upon the map. These curves represent the intersections of the surfivce of the ground with a series of horizontal planes at equal distances apart, of say 3ft. 5ft. 10ft. or more — and indicate at once to the practiced ej'e the topography of the countij which they embrace. We give. Fig. 3, the contour lines of a small tract of country, showing a variety of natural features, such as undulating slopes, steep hill sides, ravines, water, and marsh. Every curve represents a level line traced upon the ground, the vertical distance, or difEerence of level, between the curves being 3 feet.

Parallel Cross Sections.

A sui-vey so complete as would be required for mapping the contour lines in the manner shown in Fig. 3, is seldom, if ever, resorted to, and is indeed unnecessary for the proper location of a country road. It will suffice to take a series of cross sections parallel to each other, and extending a snfiicient distance laterally to embrace tlic width of the country

Fig. 3.

SECTION A-B.

PARALLEL CKOSS SECTIONS.

under examination. By plotting those sections to a scale, in their true relative positions, all referred to the same leyel or datum line, it will be easy to locate the axis of the road properly thereon, and to estimate the quantities of excavation and embankment, provided the sections are taken sufficiently near together. Their distances apart should of course be less in proportion to the ruggedness and unevenness of the country. Suppose, for example, that C, D, M, N, Fig. 4, represents a portion of the strip of country under examina ■

Fig. 4.

tion and A, B, the general direction of the road, which must be located somewhere between the lines C, M, and D, N. Having run the several lines of levels 0, D, E, P, etc., transversely, and at least one line A, B, longitudinally so as to establish a common datum line for all, the sections are drawn as shown in the figure. As a' part of the map or plan the right lines 0, D, E, P, etc., show the positions of the cross sections, while they are also the datum lines, all on the same level, of their respective sections. Those portions of each section to the left of the datum line represent ground above that line and those portions to the right, below it, and

20 KOADS, STEEETS, AKD rAYEJlENTS.

a line like 0, P, drawn through points in the several sections that are at the same distance from and on the same side of the datum lines, will show the exact location of a level line traced on the surface of the ground. Hence the axis of the road if located on the line 0, P, will be level, while upon the line Q, S, it would have an ascending grade of -^ from Q, to E, and a descending grade of -gV from R to S.

Having completed the surveys, and prepared the map and memoir with as much detail as possible, the engineer will then be able to study with intelligence the relative advantages of the trial lines, and to establish definitely their location, direction and gradients, in order that the volumes of excavations and embankments shall balance each other as nearly as possible, except when other methods, hereafter referred to would lessen the expense, while the cost of constructing tlie necessai-y bridges, culverts, etc., shall be care fully kept at the minimum.

Grades.

Upon common roads the gi'ades, or the angles which the axis of the road should make with a horizontal line, depend so much upon the kind of vehicle employed for traffic, tlie character of road-covering adopted for the surface, and the condition in wliieh that surface is maintained, that no empyrical rule can be laid down. The grade should not be so great as to require the application of brakes to the wheels in descending, or to prevent ordinaiy vehicles carrying passengers ascending at a trot. In general the gradient should be somewhat less than the anale of repose, or that angle upon which the vehicle in a state of rest would not be set in motion by its own weight, but would descend with

slow uniform velocity if very slight motion be imparted to it. Tlie grades therefore^ suitable for any road, will depend upon the condition, with.respect to smoothness and hardr ness, iu which the surface is to be maintaindd, and hence upon the kind of road-covering used ; and as the force of gravity is the same whether the road be rough and soft, or smooth and hard, steep grades are more objectionable upon good roads than upon bad.

Tractive Force.

Many ingenious experiments have been made at various times to ascertain, in functions of the quality and condition of the road surfaces, the measure of the tractive force, or the force required to overcome the resistances which oppose themselves to the movement of a vehicle along horizontal roads of different degi-ees of smoothness and hardness, and covered with different materials. From some of the experiments of M. Morin, conducted for the French government, the following general results were deduced :

1. The force of traction varies directly with the load and inversely with the diameter of the wheels.

2. The resistance is practically independent of the width of tire on paved or hard Macadamized roads, where that width exceeds 3 or 4 inches.

3. At ordinary walking speed the traction is the same for carriages with springs, as for those without them, the other conditions being the same.

4. The force of traction increases with the speed upon paved, or hai'd Macadamized roads. When the speed exceeds 3^ miles per hour the increase in the resistance varies directly with the increase in velocity.

22 EOADS, STKEETS, AKD rAVEMEXTS.

Some of M. Morin's results are tabukted below.

KiSD OP B.OJkD.

Relation op Force of DnACGHT to Weight of Vehicle and Load.

Carts.

Trncka of two tone.

CarriagcB

with seats

hnng on

spring^. ;

Now road, with gravel covering, 5 inches tliick

Solid earth causeway, with gravel covering 1^ inch thick

Earth causeway in very good condition

-A i i

Broken stone road, very

dry and smooth. .

Do. moist and dusty. . .

Do. with ruts and mud,

Do. with deep ruts and

thick mud

Ory

Pavement. J.

Muddy

Walk.

Trot.

Walk.

Trot.

■h

The smoother the road and the less rigid the Tehicle, the less will be each eqnal increase of resistance due to each equal increase of speed.

5. The traction is practically independent of the velocity upon soft dirt and sand roads, or roads freshly and thicl;ly covered with gravel.

GRADES AND TRACTIVE FOKCE. 23

6. Upon a smooth-cnt, eyonly-laicl stone pavement, the resistance at a •walking speed Ao(SS not exceed three-fourths that upon the best Macadamized road at the same speed, but at trotting speed it is equal to it.

7. The wear and tear of the road is greater as the diameters of the wheels are less, and is less from vehicles .with springs than from those without them.