PART I

SPECIFICATIONS FOR STREET ROADWAY PAVEMENTS

INTRODUCTORY

In addition to their value as memoranda and aids in preparing

specifications for a particular project, carefully prepared general

specifications, embodying the latest approved practice, sometimes supply

the most useful and acceptable brief treatises upon any particular

branch of engineering work. It has been partly with this thought in mind

that the following set of specifications for standard street pavements

has been prepared and is now offered to city engineers and municipal

authorities.

To widen their range and increase their usefulness, copious foot notes

have been added, referring to alternative requirements and methods of

construction, and giving some of the reasons for the preference or

adoption of the construction called for in the specifications. It is

recognized that in a good many matters of detail embraced in these

specifications there is difference of opinion among able engineers, many

of whom are at least as competent as the writer to determine what is

best. They are not offered in a dogmatic spirit, or with the hope that

all the provisions found therein will be accepted. If they shall be of

some assistance in bringing about correct standards for such

specifications, their preparation will have been justified.

Theoretically, three general classes of engineering specifications may

be noted. In the first, the aim of the engineer is to specify the end or

result that it is desired to secure, leaving the contractor free to

originate and follow the methods by which these results are to be

attained. In the second the engineer aims to secure the desired end by

specifying in detail the materials and the methods which in his opinion

will accomplish the purpose, he himself assuming responsibility for the

results. Either of these two classes of specifications is permissible,

and the engineer may choose the one which in his opinion seems best

adapted to the character of the work to be done, and the conditions

under which it must be prosecuted.

In the third class of specifications, met with more frequently than they

should be, the engineer undertakes to prescribe not only the character

of the materials to be used and the methods to be pursued, but also the

results to be attained. The position thus assumed is illogical, and

often unreasonable, and may lead to complications between the engineer

and the contractor. If a contractor be required to turn out a product

which shall conform to certain standards, he may properly be given much,

if not full latitude, as to how the stipulated results shall be secured,

and may be held fully responsible for the outcome; if on the other hand

the engineer chooses to specify with more or less minuteness the

character of the materials to be used and the methods of construction to

be followed, and enforces compliance therewith, it seems fair and just

that he should assume responsibility for the results produced, and

therefore unfair to hold the contractor to responsibility for

consequences arising from the use of materials and methods which he was

allowed no choice or latitude in selecting.

In street paving work, of well-known and standard character, the second

class of specifications seems preferable for a number of reasons, the

leading one being that the time required to develop the good or bad

quality of the work must usually extend over a considerable number of

years, and the conditions to which the pavement may be subjected in the

meantime are likely to vary so widely that it may be very difficult, if

not impossible, to prescribe a satisfactory standard of service and

endurance. Disputes are therefore liable to arise between the

municipality and the contractor as to the latter’s liability, or

conditions may make it difficult or impossible to hold the contractor to

strict account for that liability.

It is believed that in the present state of the art it is entirely

practicable to so frame specifications for the materials to be used and

the methods to be followed in the construction of standard street

pavements, and to so enforce compliance therewith, that the engineer and

the municipality may safely assume responsibility for the quality of the

work produced. While it may be true that local conditions sometimes make

it very difficult to enforce compliance with specifications, the same

conditions are likely to make it at least equally difficult to secure

effective responsibility on the part of the contractor for any

long-period guarantee of the work done by him; and the contractor who

negligently or purposely violates the specifications during construction

is not likely to be more faithful or scrupulous in living up to any

guarantees he may make with regard to the future, even where the terms

and conditions of such guarantees may be clearly defined and

indisputable. The writer has discussed the subject of time guarantees as

applied to street pavements pretty fully in his book, “Municipal Public

Works,” and the above brief statement seems all that is necessary here.

In conformity with this view of the matter, the following specifications

aim to set out as definitely and clearly as practicable the requirements

for the construction of good pavements of the several standard kinds,

and it is assumed that the engineer will be able to, and will enforce

them.

It is, however, not infrequently the case that the engineer will be

called upon to prepare specifications for new, or patented, or

proprietary pavements advocated by their promoters, the value or

usefulness of which have not been sufficiently established by

experience, and for which the data for detailed, definite specifications

are not yet available.

In such cases the wisest course to follow is to confine the precise

specifications to the general or standard parts of the work, while

stipulating only the _results to be attained_ with regard to those

features of the work that are proprietary or questionable, thus placing

upon the promoter or his contractors full responsibility for such

results as are promised or guaranteed. This applies to new or

comparatively untried materials or processes, whether patented or not.

A proposed form of general specifications to cover such cases is offered

herein.

It is usually unwise to adopt or to incorporate in the municipal

specifications those prepared or offered by the promoter or patentee,

which are often brief, incomplete, and indefinite, and are sometimes

carefully, and even cunningly, drawn to evade final responsibility.

No attempt has been made to submit specifications for proprietary or

patented pavements, or those composed wholly or in part of materials

which are patented or protected by trade-marks. The owners or

contractors engaged in constructing these pavements, often, if not

usually, claim the right to dictate the material parts of the

specifications under which such work shall be done, and the municipal

engineer who is called upon to construct such pavements, must, in each

case, determine whether the specifications offered are adequate and

satisfactory, and the extent to which he feels justified in accepting

responsibility for the results. Naturally, the contractor or promoter,

even if competent to prepare specifications, cannot be expected to bind

himself within closer limits than he thinks necessary to secure the

work. In many such cases the form of general specifications for “untried

or experimental pavements” given herein might appropriately be used.

The engineer is, in common with all men, fallible, and he can hardly

hope, in the preparation of specifications, to make them perfect; to

cover every item and particular; or to escape some ambiguities of

expression, and some degree of indefiniteness. The writer can only claim

that he has aimed, in the light of a considerable experience, to set out

as fully and definitely as practicable the requirements for the proper

construction of high-class street pavements, and has endeavored to avoid

loose or obscure terms and expressions. The ideal specification is one

that furnishes a wholly sufficient guide to the accomplishment of the

desired purpose; that provides for every possible contingency which may

arise, and is couched in language which not only means exactly what it

was intended to mean, but is incapable of any other interpretation. It

is needless to say that no example of such a perfect specification can

be instanced as a model.

It has been the aim to make these specifications fair and just to the

contractor; that is, to require of him no impracticable or indefinite

service, or the assumption by him of risks other than those fairly

involved in the business conduct of the work.

If the plans and specifications for any work which a contractor bids

upon are so full, specific, and clear, that he may know exactly what he

will be expected to do, and if they do not require him to assume unusual

chances and risks, he may intelligently name prices which he believes

will compensate him for the service. Having done so, his proposal having

been accepted, and a contract entered into accordingly, the engineer and

the municipality have a right both in law and equity to demand that he

will do exactly and fully what he has contracted to do. No excuses on

his part can be valid and none should be accepted. He may in all

fairness and justness be required to “toe the mark” strictly. To the

neglect to recognize and enforce these principles is chargeable the

greater part of the poor and unsatisfactory work so common in street

pavement work in our cities. Unexpected contingencies may, of course,

arise where some changes and concessions may be proper and just, but

these should be, and usually are, very rare. On the other hand, sweeping

general clauses in contracts and specifications intended to catch the

contractor “goin’ or comin’,” unnecessarily stringent stipulations which

were never intended to be strictly enforced, but were put into the

specifications with the idea that they would help hold the contractor up

to a high standard, and “one-sided” contracts intended to give the

municipality an unfair advantage over the contractor, are as inadvisable

in policy as they are wrong in principle. Nothing should be put in a

specification that is not clearly essential to secure the results aimed

at, and, this having been done, every requirement should be enforced.

The existence in specifications of requirements that are not intended to

be enforced, gives the contractor a pretext for neglecting others that

may be important.

In these specifications will be found a number of details that are often

not regarded as important and which, when found in paving

specifications, the contractor is frequently allowed to ignore. In the

writer’s opinion, based upon his experience in street paving, every one

of these requirements is essential to the production of high-class work,

which, it is hardly necessary to argue, is, in the end, the most

economical work from the standpoint of the municipality.

It may be argued that the adoption and enforcement of these

specifications would have the effect of raising prices. In many cases

this would doubtless prove true. Contractors are entitled to a fair and

reasonable compensation for their services. It is admitted that in some

cities the prevailing prices for some kinds of pavements are below the

actual cost of the work if it were done in a proper manner, conforming

strictly to the specifications. Illogical as it undoubtedly is, the low

price at which work is taken is sometimes considered a sufficient reason

for accepting work below standard. The consequence is that bidders not

only count upon concessions and lax enforcement of the specifications,

but bid lower and lower, expecting that further concessions will enable

them to get out with an undeserved profit. This is one of the most

serious evils in the paving business to-day, and the highest public

interests demand a thorough reform. Low first cost, desirable as it may

be, is the poorest economy if it be secured at the sacrifice of the

quality of the work. If one pavement costs twenty per cent. more than

another, but renders forty per cent. more service, it is obviously the

cheaper of the two.

Contractors are prone to contend that this or that provision in a

specification is unusual, unnecessary or unfair. In dealing with them

the engineer should bear in mind that no requirement of a specification

that is clearly and definitely stated, so that the bidder may understand

exactly what it means and what he will be expected to do, and may frame

his prices accordingly, can be unreasonable or unfair to the contractor.

Unusual or unnecessary requirements may result in unwarrantably

increasing the cost of the work, and this may raise a question between

the engineer and the municipality employing him, but it can furnish no

occasion for questions of fairness or unfairness between the contractor

and the engineer.

The relations that should exist between the contractee and the

contractor, and the attitude of the engineer toward the contractor have

been widely discussed and are quite well understood from both the

ethical and legal standpoint.

It is well to bear in mind that when a contract is duly entered into,

both the parties thereto are equal before the law. Neither can impose

upon the other terms or conditions that are not clearly included in or

to be fairly inferred from the contract itself. The assumption that

either party has superior or extra rights not expressed or to be fairly

inferred from the written agreement, or in accordance with the

established rulings of the courts, is wholly without warrant. The

smallest contractor is, in this respect, upon an equal footing with the

largest city government for which he may undertake to do contract work.

It is not infrequently the case that the city assumes a superior and

dictatorial attitude not in harmony with these principles, and it is too

common for the contractor to seek to evade or to escape from clear

contractural obligations. In neither case is the action warranted by

fairness, justice, or law.

It should be needless to say that the attitude of the engineer toward

the contractor should be one of unyielding and uncompromising

requirement that the contract and specifications shall be fully and

faithfully complied with, but at the same time one of absolute fairness

and even helpfulness to the contractor. The ideal relation, which should

be more commonly attainable than it appears to be, is that of helpful

cooperation to bring about the results the contract and specifications

were intended to secure.

In line with the principles here outlined some observations upon the

preparation of contracts and specifications are appropriate.

It is the general practice to include in and make a part of “The

Contract” (herein for convenience called The General Contract) all the

various documents that are supposed to relate directly to the

transaction as a whole. The separate parts of such a general contract

may vary in number or character, but the principal ones are the

following:

1. The advertisement for proposals.

2. Instructions to bidders.

3. The proposal submitted.

4. The contract proper.

5. The specifications.

Each of these should be drawn to cover fully and clearly its appropriate

purpose or function but _nothing more_. It is not unusual to find, even

in the instructions to bidders, stipulations that properly belong in the

contract or specifications, and it is quite common to find in the

contract proper a lot of matter that properly belongs in the

specifications only. In such cases there is liable to be more or less

confusion as to the actual meaning or requirements of the general

contract as a whole, which may lead to serious misunderstandings and

complications between the parties thereto. The several documents

composing the general contract are likely to be prepared by different

persons, looking at the transaction from different points of view, and

often not wholly familiar with the scope, intent and language of the

other documents. There is therefore a possibility, at least, of

indefinite, if not of conflicting expressions which are open to

different interpretations, particularly in the light of special or

unexpected conditions that may arise during the progress of the work or

the settlement therefor. It would tend to eliminate or avoid the

possibility of such complications if each of the several documents

confined itself strictly to its appropriate function in the general

contract.

Advertisements for proposals may be divided into two general classes.

The one is brief in form and substance, simply stating that proposals

for a certain named work will be received at a stated place and time,

and referring those interested to documents on file at a stated place

for all further information. This is the general form adopted by the

United States War Department for the many projects carried out by

contract under its direction. A sample advertisement taken from a

current technical journal is as follows;

TREASURY DEPARTMENT, OFFICE OF the Supervising Architect, Washington,

D. C., October 10, 1912. Sealed Proposals will be received at this

office until 3 o’clock p. m. on the 1st day of November, 1912, and

then opened, for an electric passenger elevator in the United States

post office, Bellingham, Wash., in accordance with the drawing and

specification, copies of which may be had at this office at the

discretion of the Supervising Architect. OSCAR WENDEROTH, Supervising

Architect.

The other general class of advertisement, very commonly used by

municipal corporations, is much longer and more elaborate, giving a

condensed statement of the character of the work to be done, the

conditions under which proposals are invited and will be received, and a

schedule of the quantities of work involved, together with other

particulars. A typical example of such an advertisement, taken from the

same periodical, is here given:

PUMPING MACHINERY—ROSELAND PUMPING STATION

DEPARTMENT OF PUBLIC WORKS

CHICAGO, ILL., October 2, 1912.

Sealed proposals will be received by the City of Chicago until 11 A.

M. Wednesday, October 30, 1912, at Room 406, City Hall, for furnishing

and erecting at Roseland Pumping Station one vertical triple expansion

crank and fly wheel pumping engine of a capacity of twenty-five

million (25,000,000) gallons per day against a normal head of one

hundred and forty feet (140′). This proposal also includes the

dismantling of a similar engine now at Lake View Pumping Station,

transporting and erecting it at Roseland Pumping Station, together

with the furnishing and erection of certain auxiliaries and

appurtenances, according to plans and specifications on file in the

office of the Department of Public Works of said city, Room 406, City

Hall.

Proposals must be made out upon blanks furnished at said office, and

be addressed to said Department, indorsed “Proposals for Pumping

Machinery, Roseland Pumping Station,” and be accompanied with Five

Thousand ($5,000) Dollars in money or a certified check for the same

amount on some responsible bank located and doing business in the City

of Chicago and made payable to the order of the Commissioner of Public

Works.

The Commissioner of Public Works reserves the right to reject any or

all bids. A deposit of One Hundred Dollars ($100) will be required to

insure safe return of the plans.

No proposal will be considered unless the party offering it shall

furnish evidence satisfactory to the Commissioner of Public Works of

his ability, and that he has the necessary facilities together with

sufficient pecuniary resources to fulfill the conditions of the

Contract and Specifications, provided such Contract should be awarded

to him.

Companies or firms bidding will give the individual names as well as

the name of the firm with their address.

L. E. McGANN,

_Commissioner of Public Works_.

Such advertisements as this may be required by statutes or ordinances,

and in that case are, of course, proper and necessary. Even where not so

required they may be considered advantageous, because they give

prospective bidders more complete information as to the character and

magnitude of the work, and may enable them to decide at once whether

they care to pursue the matter further. But on the whole, the shorter

form of advertisement, if permissible, seems preferable, because it

refers the enquirer directly to the original and official sources of

information, the forms to be used, the contract, specifications and

estimated quantities of work, exactly as they will and must be presented

to all bidders, and as they will appear in the subsequent stages of the

transaction, and leaves, therefore, no room for possible confusion of

statements between the advertisement and the other documents.

Furthermore, the cost of the shorter form of advertisement is much less,

and this is often a matter of some importance.

Instructions to bidders should be confined strictly to such information

and directions as the bidder may need to properly and intelligently make

up and submit his proposal in accordance with the requirements relating

thereto. This should include primarily, a reference to the contract and

specifications for all general and detailed information about the work

to be done, but should carefully avoid any statements or language that

might be construed to add to, take from, limit or modify the contract or

specifications. Perhaps the briefest and best statement of what this

document should or should not contain is that it should be so framed

that, except as a matter of record, its office and usefulness should

absolutely end with the award and signing of the contract.

No one who is not a lawyer can presume to say just what the contract

proper should contain or cover, particularly as this may vary with the

requirements of statutes and ordinances in force in a given city. It

would seem logical and proper, however, to separate the special

functions of contracts and specifications in such a way that each should

cover a distinct field of its own, and be free from encroachment upon

the proper domain of the other. With such a conception of the proper

domain of each, one might safely say that the contract should undertake

to set out only the legal and contractural relations of the parties

thereto, and should refer to the plans and specifications for all

detailed instructions as to the actual performance of the work and the

results to be secured.

In the preparation of specifications for any public work the main points

to be kept in mind are fulness, definiteness, and exact expression.

While brevity and conciseness are desirable qualities in any document,

they should not be secured at the expense of completeness and precision

of statement. Even the frequent repetition of words, phrases and

sentences throughout a document, where it is necessary to avoid the

possibility of misunderstanding or ambiguity, should be resorted to

freely. Exact description and definition are more important than

literary style, though they may often be successfully combined. Of

course, it is not possible or necessary to go into minute detail with

regard to every part of the work. Certain things may be safely assumed

to be required by established practice or trade usage. If, for instance,

it is specified that certain lumber shall be “dressed” this word has a

well-understood meaning in the trade and it is unnecessary to stipulate

how the dressing shall be done or its character or quality, though it

may be necessary to say whether it is to be dressed on one or more

sides.

The proper preparation of specifications for any work involves a clear,

distinct and complete conception, determination and design of what is to

be done; of the conditions that are likely to be met with in carrying it

out; and of alternate plans that these conditions may necessitate. This

may not always be possible, for the engineer is not omniscient. But

careful study and maturity of design will enable him to avoid the great

majority of such indefinite expressions as “or in such other manner as

the engineer may direct,” “in accordance with the instructions of the

engineer,” etc. A great many of the items to which such expressions are

intended to and do apply in practice, could be definitely settled before

the specifications are prepared and thus all uncertainty on the part of

both engineer and contractor be avoided. To illustrate: specifications

for block pavement commonly stipulate that the blocks shall be set in

rows running at right angles to the axis of the street, except at street

intersections, where the engineer may direct them to be laid at a

different angle. There is usually no good reason why the engineer should

not determine beforehand at which, if any, street intersections the

general rule should be changed and so state in the specifications. These

may be and usually are unimportant matters which may not much affect one

way or the other the cost to the contractor. But they often prove

otherwise, and the contractor is entitled to know when he submits his

proposal just what he will be required to do. Of course it may develop

during the progress of the work that changes from the original plan will

become necessary, but these should be provided for in some such definite

and previously stipulated manner as outlined in Sect. 3 of the following

specifications.

The practice of inserting, either in the specifications or the contract,

a clause making the engineer judge and arbiter in any differences that

may arise between the city and the contractor, and providing that his

decision in all such cases shall be final, is as unwise as it is often

illegal. Such clauses are based on the assumption that the engineer is a

competent as well as a disinterested party in the transaction, an

assumption that is usually wholly wrong, though to their honor it may be

said that the confidence thus reposed in engineers is seldom abused. But

the fact is that the engineer is never actually a disinterested party.

He is employed and paid by the city to look after its interests, and is

under no obligations to the contractor other than those named in the

contract and specifications and his sense of justice, propriety and

professional honor. He would be recreant to his duty if in all nicely

balanced matters of doubt he did not espouse the side of his employer.

Moreover, his personal interests are often involved. Having prepared the

plans, specifications and estimates for the work, he is naturally and

properly anxious that it shall be successful and that the cost shall not

exceed that estimated. Under all these conditions it is hardly possible

for any human being to be a wholly disinterested and unprejudiced judge.

No broad-minded and conscientious engineer desires to be placed in such

a difficult position, and it is as unfair as it is unwise and improper

to require him to assume it.

There are, however, a number of matters of fact in reference to which it

is proper and necessary to make the judgment and decision of the

engineer controlling and final, unless it may be shown that his decision

is clearly erroneous or affected by improper motives, or by fraud. Some

one must necessarily be made the immediate and final judge as to whether

the quality of materials and workmanship is in accordance with the

requirements of the plans and specifications, and as to the quantity of

work actually performed, and these duties and responsibilities are very

properly placed upon the engineer.

It not infrequently occurs that specifications are not drawn as clearly

as they should be in the matters of methods of measuring the work and of

applying contract unit prices, and indefiniteness and carelessness in

this regard are often a source of misunderstanding and dispute between

the engineer and the contractor. It is a good practice, followed by many

able engineers, after specifying how a certain part of the work shall be

done, to state how it shall be measured and paid for at the contract

unit prices.

In many respects it is desirable that all the work to be done under

contract should be quite fully itemized, and a unit price named for each

kind of work. It is the custom in many cities to name only certain

leading items of the work to be done under a paving contract, as for the

pavement complete, furnishing and setting new curbing, redressing and

resetting old curbing, and possibly a few other leading items, and to

require that all necessary incidental work shall be done by the

contractor without cost to the city; or, in other words, he must take

this possible extra work into consideration in naming his unit prices

for the leading items of the work. As the quantity of this incidental

work is often not stated, and the contractor has no means of

ascertaining it, he must guess, as intelligently as he may be able, how

much he should add to his unit prices to cover its cost. If he is a

prudent contractor he will be sure to add enough to prevent any possible

loss on this account. In most cases the quantities of this incidental

work can be determined and scheduled by the engineer with the more

important items, and the contractor may be required to name unit prices

for it. True, there are likely to develop during the progress of the

work some items that could not be foreseen or that were overlooked. In

some cities such contingencies are provided for by a clause in the

contract or specifications scheduling, by name, all the incidental minor

items of work that experience has shown are likely to be met with in

street paving contracts, and naming fair unit prices which the

contractor will be paid for each, should it occur. The contractor may

then feel assured that however much the quantity of such incidental work

may vary, he will receive compensation proportionate thereto, and he may

name his prices for the main items with more confidence. Under such

conditions it is reasonable to expect closer figures than he would be

willing to name if an unknown quantity of incidental work for which no

separate pay is provided had to be taken into consideration.

Sub-division of unit prices is also desirable in order that the engineer

may be able to analyze and record the elements that make up the

aggregate cost of the work. Thus, in the case of the construction of a

new sheet asphalt pavement it is common to ask for a single price for

the pavement complete, including a five year guarantee. Now the work

will consist of several distinct operations or kinds of work for each of

which a separate price might be named:

1. The grading of the street and preparation of the sub-grade. The

quantity of this work will vary on different streets and is best

reckoned by the cubic yard of material excavated.

2. A price, either per cubic yard or per square yard for the concrete

foundation.

3. A price per square yard for the asphalt pavement proper. This might,

if desired, be sub-divided into separate prices for the base-course and

the surface-course.

4. A price per square yard for guaranteeing the pavement for five years.

Such sub-division would, it is true, increase the work of final

computation but if of no other value, the detailed costs would be a

great aid to the engineer in estimating the reasonable cost of future

work where the relative quantity of these detailed parts varied.

SPECIFICATIONS

For Grading and Paving, or Repaving

with.. ........ ........ .............. .... Pavement

on a... ......... .......... ...... Foundation, the Roadway

of..... ........ ........... ............ . ............

Street, from...... .......... ............. .............

to. ....... ....... ........... ............ ........

together with work incidental thereto.

GENERAL DESCRIPTION OF WORK

The work embraced in and to be done under this contract consists of

grading the entire street from curb to curb between the limits named,

including the removal or readjustment of the pavement now on the

roadway, setting and resetting curbing, laying or relaying sidewalks

where required, furnishing all new material and performing all the labor

required for paving the roadway, together with all incidental work

necessary to complete the whole in a proper manner, in accordance with

the contract, the plans on file in the office of the City Engineer,

these Specifications and the instructions of the City Engineer, herein

referred to as the Engineer, or his authorized agents.

REFERENCES

The numbered divisions of these specifications are herein designated as

“sections,” each being referred to by the number standing at its

beginning. Where reference is herein made to any such section number it

shall be considered equivalent to a quotation of that section.

The plans and drawings relating to this work, on file in the office of

the City Engineer are designated as ...

=1. Authority.=—Wherever, in these specifications, the words, the City,

are used, they shall be understood to refer to the duly constituted

municipal government of the city of ... or its authorized agents, acting

within the authority specifically conferred upon them by the said

municipal government.[1]

Wherever, in these specifications, the words, the Engineer, shall be

used, they shall be understood to refer to the City Engineer of said

city, or his deputies or assistants, acting within the authority

conferred upon them by the City Engineer.

But no agent of the city shall have power to revoke, alter, enlarge or

relax the stipulations or requirements of these specifications, except

in so far as such authority may be specifically conferred in or by the

specifications themselves, without the formal authorization so to do,

conferred by the contract of which these specifications are a part, or

by ordinance, resolution or other usual official action of the city.[2]

=2. Interpretation.=—In case of any actual or alleged disagreement or

discrepancy between the contract, these specifications, and the plans

for the work on file in the office of the Engineer, the language and

provisions of the contract shall take precedence and prevail; and the

Engineer shall determine in each case whether the specifications or the

plans shall be followed.

=3.= The Engineer shall have the right to make such changes in the plans

and specifications of the work as he may deem necessary or desirable or

to provide for unexpected conditions or contingencies that may develop

at any time after the signing of the contract, or during the progress,

or before the final acceptance of the work; provided that all such

changes do not involve an aggregate increase or decrease in the cost of

the work, as shown by his estimates, of more than ten (10) per cent. The

contractor shall accept such changes when made, as a part of the

original contract and specifications, subject to all the provisions and

conditions thereof. But before any such changes shall become valid and

before the contractor shall begin the particular work involved in such

changes, the increased or decreased cost of the work by reason of such

changes, above or below what it would have been under the original plans

and specifications, shall be agreed upon in writing between the engineer

and the contractor. And when the whole work, including such changes,

shall have been completed and accepted by the engineer, the sum or sums

so agreed upon shall be added to or deducted from the sum that would

have been due the contractor if no such changes had been made.

=4. Quality of Material and Work.=—The judgment and decision of the

Engineer as to whether the materials supplied and the work done under

this contract comply with the requirements of these specifications,

shall be conclusive and final. No material shall be used in the work

until it has been examined and approved by the Engineer, or his

authorized agents. All rejected material must be promptly removed from

the work and replaced with that which is acceptable to the Engineer, and

all improper or defective work must be corrected, and, if necessary,

removed and reconstructed so as to comply with these specifications and

the instructions of the Engineer.

In all matters of detail not specifically covered by the specifications

the work shall be well and skillfully done in accordance with the best

trade or art customs and standards for work of like character and

purpose.

=5. Inspection.=—The Engineer may provide for the inspection, by

assistants and inspectors under his direction, of all materials used and

all work done under this contract. Such inspection may extend to all or

any part of the work, and to the preparation or manufacture of materials

to be used, whether within the limits of the work on the street, or at

any other place. The Engineer and his inspectors shall have free access

to all parts of the work, including mines, quarries, manufactories, or

other places where any part of the materials to be used is procured,

manufactured or prepared. The Contractor shall furnish the Engineer all

information relating to the work and the material therefor which the

Engineer may deem necessary or pertinent, and with such samples of

materials as may be required. The Contractor shall, at his expense,

supply inspectors with such labor and assistance as may be necessary in

the handling of materials for proper inspection. Inspectors shall have

authority to reject defective material and to suspend any work that is

being improperly done, subject to the final decision of the Engineer.

Inspectors shall have no authority to permit deviations from, or to

relax any of the provisions of these specifications without the written

permission or instruction of the Engineer; nor to delay the Contractor

by failure to inspect materials and work with reasonable promptness.

The payment of any compensation, whatever may be its character or form,

or the giving of any gratuity, or the granting of any valuable favor, by

the Contractor to any inspector, directly or indirectly, is strictly

prohibited, and any such act on the part of the Contractor will

constitute a violation of these specifications.[3]

=6. Injuries to Persons and Property.=—The Contractor shall be held

alone responsible for all injuries to persons, and for all damages to

the property of the city or others, caused by or resulting from the

negligence of himself, his employees or agents, during the progress of,

or connected with the prosecution of the work, whether within the limits

of the work, or elsewhere. He must restore all injured property,

including sidewalks, curbing, sodding, pipes, conduits, sewers and other

public or private property to a condition as good as it was when he

entered upon the work.

=7. Sanitary Conveniences; Nuisances.=—The Contractor shall provide all

necessary privy accommodations for the use of his employees on the

street, and shall maintain the same in a clean and sanitary condition.

He shall not create nor permit any nuisance to the public or to

residents in the vicinity of the work.

=8. Public Convenience.=—No material, or other obstruction shall be

placed within five feet of fire hydrants, which must be at all times

readily accessible to the Fire Department.

During the progress of the work the convenience of the public and of the

residents along the street must be provided for as far as practicable.

Convenient access to driveways, houses and buildings along the street

must be maintained wherever possible. Temporary approaches to and

crossings of intersecting streets and sidewalks must be provided and

kept in good condition, wherever practicable.

=9. Barriers, Lights, Watchmen.=—The Contractor shall provide and

maintain such fences, barriers, “street closed” signs, red lights, and

watchmen as may be necessary to prevent avoidable accidents to residents

and to the public.

=10. Disorderly Employees.=—Disorderly, intemperate, or incompetent

persons must not be employed, retained, or allowed upon the work.

Foremen or workmen who neglect or refuse to comply with the instructions

of the Engineer, shall, at his request, be promptly discharged, and

shall not thereafter be re-employed without his consent.

=11. Order and Progress of Doing Work.=—The work under this contract

shall be prosecuted at as many different points, at such times, and in

such sections along the line of the work, and with such forces as the

Engineer may from time to time deem necessary, and direct, to secure its

completion within the contract time. Not more than one thousand (1,000)

linear feet of the street shall be torn up, obstructed or closed to

travel at any one time without the written permission of the Engineer.

Completed portions of the pavement shall be opened to travel as directed

by the Engineer, but such opening shall not be construed as an

acceptance by the City of the work done. Where thus opened to public

travel by the direction of the Engineer, the Contractor will not be held

responsible for injuries to the work caused by such travel or public

use, pending the final completion and acceptance of the whole work.

=12. Grade and Contour of Pavement.=—Roadway pavements shall be laid to

such grades, crown and contour of surface as the plans may show or the

Engineer may direct, and the surface of the completed pavement shall

conform accurately to such grades, crown and contour. The designed

surface of the completed pavement shall be considered as the datum or

plane of reference in fixing the location or level of the sub-grade, of

the pavement foundation, and of structures connected therewith. It will

be hereafter referred to in these specifications as “The pavement

datum.”

=13. City Monuments or Stakes.=—The Contractor must carefully protect

from disturbance or injury all city monuments, stakes and benchmarks,

and shall not excavate nearer than five feet to any of them without the

permission of the Engineer; or until they have been removed, witnessed,

or otherwise disposed of by the Engineer.

=14. Old Material.=—All material or structures removed from the street

and not required for the new construction, but which the city may desire

to reserve, shall be delivered and neatly piled up in a corporation yard

or elsewhere, by the Contractor, as the Engineer may direct. Such

reserved material shall be considered in the custody of the Contractor

until delivered at the place designated, and he will be held responsible

for its care and protection, and must make good any losses occasioned by

damage, theft, or misappropriation while it is on the street or en route

to the place of storage. If the Contractor shall be required to haul

such reserved material more than one-half mile, he shall be paid a

reasonable price, to be agreed upon in advance, for the haul exceeding

that distance.

Material taken from the work which is to be used in the new construction

shall be compactly piled where it will least obstruct the sidewalks or

adjoining sections of the street, and properly protected by the

Contractor until it is required for use.

All old material removed from the work, including the material excavated

in preparing the sub-grade, not reserved by the City nor to be used

again in the work, shall belong to the Contractor and must be removed by

him from the street as promptly as possible. It must not be placed on

the sidewalks or adjacent streets, nor on any other street or property

belonging to the City, nor on the property of private owners, without

the written consent of the Engineer, or the owner of the property.

=15. Storage of New Material.=—The material for construction when

brought upon the street shall be neatly piled so as to cause as little

obstruction to travel as possible, and so that it may be conveniently

inspected.

=16. Rebuilding and Adjusting Street Structures.=—Catch basins, manhole,

sewer and water frames and covers, sewer inlets, water pipes and other

conduits, belonging to the City and within the limits of the work,

shall, if necessary, be reset to the new lines and grades of the street

and for this purpose good brick masonry of the original thickness, laid

in Portland cement mortar shall be used. Great care must be taken to set

all such structures as project through the pavement exactly to the grade

and contour of the new street surface, and any defects in the conformity

of such structures to the pavement datum, discovered at the time, or

during the progress of the work, or during the guaranty period,

stipulated in Sec. 25 shall be promptly remedied by the Contractor.

=17. Clean Sidewalks.=—During the progress of the work, the sidewalks

and portions of the street adjoining the work, or in its vicinity, must

not be obstructed or littered more than may be absolutely necessary, and

the adjacent sidewalks must be kept clean.

=18. Connection With Existing Pavements or Streets.=—Wherever a new

pavement joins or abuts against an existing pavement of a different

kind, or an unpaved street, either at the end of the new pavement or at

cross or intersecting streets, a line of stone headers shall be provided

and set. The stone shall be of sound, hard limestone, sandstone, granite

or bluestone, free from injurious imperfections. The separate stones

shall be not less than three (3) feet long, at least eighteen (18)

inches deep, not less than four and one-half (4½) inches wide at the

top, nor less than three (3) inches wide at the bottom. The top shall be

of uniform width for each line of headers, and shall be dressed square

and even. The ends shall be dressed to secure a joint not wider than

one-half (½) inch for a depth of six inches from the top, and the sides

dressed so as to secure good contact and close jointing with the

pavement. The stones shall be set accurately with their tops at the

pavement datum, on a bed of concrete nine (9) inches wide and six (6)

inches deep, and after being set the trench shall be filled and rammed

full of gravel or crushed stone.

All existing pavements adjoining or abutting against the new pavement,

with their crosswalks, curbs, and gutters, shall be adjusted, or taken

up and relaid, to conform to and connect with the pavement datum, to

such an extent as the Engineer may direct.

Where the new and adjoining pavement are of the same kind, and headers

are not used, the new and the old pavement must be properly joined and

connected, as the Engineer may direct.

Stone headers will be paid for by the linear foot at the contract price

for that item, and the other work embraced in this section will be paid

for at the contract prices for the several items, where such contract

prices are provided; otherwise the work shall be considered as

incidental work and shall be done at the expense of the Contractor.

=19. Curbing to be Completed in Advance.=—The setting of all new curbing

and guttering and the redressing, resetting or readjustment of all old

curbing must be completed at least 100 feet in advance of the

construction of the street foundation.

=20. Final Cleaning Up.=—Immediately after the completion of the work or

any consecutive portion of it, the Contractor shall remove from it all

unused material, refuse and dirt placed by him on, or in the vicinity of

the work, or resulting from its prosecution, and restore the street to a

condition as clean as before the work was begun; and the new pavement

shall be properly cleaned.

=21. Measurements and Computations.=—Unless otherwise distinctly

provided in the contract and specifications, measurements, computations

and payments will be based upon the actual quantities of completed work,

customary or conventional methods of measurement and computation to the

contrary notwithstanding.

The area of street pavement shall be reckoned in square yards of

completed pavement surface, deducting manholes, inlets and other

openings in the surface of the pavement having an area of over three (3)

square feet. Unless separately paid for under the contract, stone

headers and crosswalks will be measured as a part of the pavement

surface.

=22.= The price for the pavement per square yard shall, unless otherwise

stated herein, include the preparation of the sub-foundation, the

construction of the foundation, the cushion course, and the pavement

complete, including all the materials and labor required therefor.

=23. Incidental Work at Contractor’s Expense.=—All the work to be done

by the Contractor for which specific unit prices are not named in the

contract, specified and enumerated in Sections 4, 5, 6, 7, 8, 9, 12, 13,

14, 15, 16, 17, 18, 19, and 20, as well as any minor details of work not

specifically mentioned in the specifications, but obviously necessary

for the proper completion of the work, shall be considered as

incidental, and as being a part of and included with the work for which

prices are named in the contract. The Contractor will not be entitled to

any extra or additional compensation therefor.

=24. Extra Work.=—The City may require the Contractor to furnish such

additional materials and to do such additional work, not provided for in

the contract and these specifications, but which may be found necessary

or pertinent to the proper prosecution and completion of the work

embraced in the contract, at prices to be agreed upon in writing, in

advance. But no work other than that included in the contract and these

specifications and which is covered by and to be paid for at the prices

named in the contract, shall be done by the Contractor except upon a

written order from the Engineer, which order shall describe the work to

be done and name the compensation agreed upon therefor. In the absence

of such written order from the Engineer the Contractor will not be

entitled to payment for any such additional or extra work.

In the same manner the city may omit or dispense with items or parts of

the work, by previous agreement with the contractor, and a like written

order by the engineer. But such additions, omissions or alterations

shall not together increase or decrease the aggregate cost of the whole

work more than fifteen per cent. (15%). Any changes in the plans,

specifications, character of material used or method of doing the work

that may increase or decrease the aggregate cost of the work more than

fifteen per cent. (15%) may be authorized and validated only by a

formal, supplemental contract, regularly executed by all the parties to

the original contract.[4]

=25. Guaranty.=[5]—The Contractor shall guarantee that all the materials

used and all the work done under this contract shall fully comply with

the requirements of these specifications, the plans herein before

referred to and the instructions of the Engineer. Any defects in the

completed work, or any part of it, or any failure of the work to fully

perform or endure the service for which it was intended, which, in the

opinion of the Engineer, are attributable to the use of materials,

skill, or workmanship not in compliance with the said specifications,

plans and instructions, within a period of ... years after the date of

the certificate of completion and acceptance, shall be regarded as prima

facie and conclusive evidence that the Contractor has failed to comply

with the said specifications, plans and instructions. And the Contractor

shall, at his own expense, at such time and in such manner as the

Engineer may direct, repair or take up and reconstruct any such

defective work, in full compliance with the original specifications,

plans and instructions. And as surety for the performance of this

guaranty the Contractor’s bond, required by the contract, shall remain

in full force until the expiration of the period of ... years above

stipulated in this section.

PREPARING THE SUB-GRADE

=26. Grading.=—The whole area to be occupied by the pavement and its

foundation shall be excavated or filled up to a sub-grade at such an

elevation that after being compacted by the roller, the surface will

be ... inches below the pavement datum, and truly parallel thereto. In

excavating, the earth must not be disturbed below the sub-grade. Plowing

will not be permitted where the depth of earth to be removed is less

than five (5) inches, and in no case must the plow be allowed to

penetrate to within less than one inch of the sub-grade. Places that are

found to be loose, or soft, or composed of unsuitable material, below

sub-grade, must be dug out and refilled with sand, or other material as

good as the average of that found on the street.

Where the natural surface of the ground shall be below the sub-grade, or

shall become so by the removal of old pavement or other structures, it

must be filled to the sub-grade in layers not exceeding five inches in

depth, and each layer shall be thoroughly rolled or rammed before the

next layer is placed upon it, and when the filling is completed the

filled area must be properly trimmed and compacted by rolling or ramming

to the true sub-grade, as in excavation. The material excavated from the

street may be used for such filling, provided it be of suitable quality.

Where it cannot be thus procured from the street it must be obtained by

the Contractor elsewhere, in which case the actual quantity so obtained,

measured after it is compacted in the street, will be paid for at the

contract price for “earth filling.” The price bid for “earth excavation”

will be paid for all material excavated above the sub-grade, measured in

place on the street, which price includes the cost of disposing of the

excavated material, whether as waste or filling, and of trimming and

rolling or ramming the sub-grade, and of making it ready for the

pavement foundation.

After the excavation is completed and the surface neatly trimmed, the

whole area shall be well compacted by rolling with a roller weighing not

less than five tons. Areas inaccessible to the roller shall be rammed

until they are as well compacted as the rolled surface. When the rolling

is completed the surface must be nowhere more than three-fourths inch

below, nor more than three-eighths inch above the true sub-grade. If,

after the rolling is completed and before the pavement foundation is

laid, the surface shall become disturbed in any way, it must be replaced

and properly compacted.

Where the soil composing the sub-foundation is found to be wet or

“springy,” a system of soft tile drains, discharging into the street

drainage system, shall be constructed by the Contractor, as directed by

the Engineer. The tile shall be laid in trenches about one foot wide and

from one to two feet deep. After the tile is in place the trenches shall

be filled with crushed stone or gravel, well compacted by tamping. The

tile will be paid for per linear foot at the contract price for the

same, which price shall include the cost of excavating and refilling the

trenches with crushed stone.

PAVEMENT FOUNDATION

=27.= Pavement foundation shall consist of hydraulic concrete, or of old

pavement stone relaid, or of broken stone or gravel, as may be herein

specified, constructed upon the sub-grade.[6]

HYDRAULIC CONCRETE FOUNDATION

=28. Concrete.=—Concrete shall be composed of Portland cement, sand,

broken stone and water.

=29. Portland Cement.=[7]—Portland cement shall be defined as the

pulverized product resulting from the calcination to incipient fusion of

an intimate mixture of properly proportioned argillaceous and calcareous

materials, and to which no addition greater than three per cent. has

been made subsequent to calcination.

=Specific Gravity.=—The specific gravity of the dry cement at a

temperature of two hundred and twelve (212) degrees F. shall not be less

than 3.10.

=Fineness.=—It shall be pulverized to such fineness that not more than

eight (8) per cent. shall fail to pass a number one hundred (100) sieve

and not more than twenty-five (25) per cent. shall fail to pass a number

two hundred (200) sieve.

=Time of Setting.=—At the temperature of sixty (60) degrees F. mortar

made of neat cement shall not begin to set in less than thirty (30)

minutes, nor set hard in less than one hour, but must set hard within

ten (10) hours.

=Strength.=—When thoroughly mixed dry with clean, sharp, moderately

coarse sand, in the ratio by weight of one part cement to three parts of

sand, and then made into stiff mortar, briquets made from this mortar

and exposed for one day to moist air and immersed in water for the

balance of the periods named below, shall develop a tensile strength per

square inch not less than the following:

In seven days 175 pounds.

In twenty-eight days 250 pounds.

=Constancy of Volume.=—When subjected to standard tests for constancy of

volume, the cement shall show no tendency to swell or crack.

=Composition.=—The cement shall not contain more than one and

three-fourths (1.75) per cent. of anhydrous sulphuric acid, nor more

than four (4) per cent. of magnesia.

=Tests.=—Cement tests shall be conducted in accordance with the methods

recommended by the “Committee on Uniform Tests of Cement” of the

American Society of Civil Engineers.

=Conditions.=—All cement shall be supplied in original packages with the

brand of the manufacturer marked on each package. It shall be protected

during transportation from rain and moisture. It shall be delivered upon

the work at least ten (10) days (exclusive of Sundays and holidays)

before it is to be used, in order to allow of proper inspection, and the

contractor shall furnish all necessary facilities for such inspection.

Brands of cement without established good reputation, or not heretofore

used in the City of ... may be rejected; or they will be accepted only

after they satisfactorily pass the 28–day test. Rejected cement must be

at once removed from the street.

=30. Sand.=—Sand for concrete shall be composed of grains not softer

than hard limestone. It shall be moderately coarse and preferably made

up of grains of varying size producing a mass with low percentage of

voids. It shall not contain, in all, more than seven (7) per cent. by

volume of clay, loam, mica scales, silt, or other objectionable

inorganic matter, nor more than one (1) per cent. of organic matter.

=31. Broken Stone.=—Broken stone for concrete shall be of hard and sound

limestone or other stone equally hard and durable, broken to a roughly

cubical form. It shall be screened through efficient revolving screens,

and only such fragments as have passed through circular screen openings

two and one-half (2½) inches in diameter, shall be used. If the crushed

dust and fine fragments be not screened out, the stone must be so

handled that the fine material will be evenly distributed through the

mass when it reaches the concrete platform or mixer.[8]

=32. Water.=—Water used for concrete shall be fresh, and reasonably

clean.

=33. Care and Handling of Concrete Material.=—Cement must not be allowed

to become wet or damp. It shall be stored until used, whether in

storehouses or on the street, so that no part of the packages shall be

nearer than four (4) inches to the ground or pavement, and shall be

effectually covered so that rain cannot reach it. Sand and stone, if

stored on the street, shall be on lumber floors.[9] The stone shall be

thoroughly wetted a sufficient time before being placed in the concrete

to allow any surplus water to drain away, but shall remain moist where

it reaches the concrete platform or mixer.

=34. Ratio of Concrete Materials.=—Concrete will be composed of one part

Portland cement, ... parts of sand and ... parts of broken stone, and

the proper quantity of water, all measured by volume.[10] The unit of

measurement shall be the barrel of cement which shall be considered as

containing four (4) cubic feet. The materials shall each be measured in

such manner and with such accuracy that the quantities used will not

vary more than seven (7) per cent. from the quantities required in the

ratio named above for each batch of concrete.

=35. Mixing Concrete.=—If mixed by hand, concrete shall be mixed on

platforms of iron or wood of sufficient size to admit of proper

manipulation of the concrete. The sand shall be first spread evenly over

the platform and the cement evenly distributed over the sand. These two

materials shall then be mixed dry until a uniform and homogeneous

mixture is secured. Sufficient water shall then be added and the mixing

resumed and continued until a mortar of uniform consistency and texture

is produced and distributed in an even layer over the platform. The

stone shall then be distributed over the mortar and mixed therewith

until the mortar is evenly distributed through the mass and every

fragment of stone is well coated with mortar, sufficient additional

water being added as the mixing progresses to produce a rather wet, but

not sloppy, concrete.[11] Machine mixing of concrete will be preferred,

provided the machine used secures equal accuracy in the ratios of

materials and equally as good mixing as prescribed above for

hand-mixing. Machine-mixed concrete must be delivered from the machine

upon a wood or metal platform, or directly into barrows.

=36. Placing the Concrete.=—Concrete shall be placed on the sub-grade in

such a manner as to prevent as far as possible the separation of the

mortar from the stone. It shall be evenly distributed in a single

horizontal layer of such depth that, after ramming, it will be not less

than ... inches thick. Immediately after being so placed it shall be

well rammed until a compact mass is produced with its upper surface

parallel to and ... inches below the pavement datum. Depressions that

may appear during the ramming may be filled with concrete of the same

composition as used for the foundation, except that smaller-sized stone

shall be used; mortar alone must not be used for this purpose, nor shall

the upper surface of the concrete be plastered with mortar. The surface

of the concrete shall not be broomed or troweled.[12]

=37. Setting of Concrete.=—After the concrete is completed it shall

remain undisturbed until it be firmly set. The time allowed for setting

shall not be less than five days, and as much longer as, in the judgment

of the Engineer, may be necessary, depending upon the temperature of the

weather and the setting qualities of the cement. During this period no

hauling or traveling over the concrete must be permitted unless its

surface be first protected by a covering of plank. The Contractor shall,

if necessary, keep the concrete moist by wetting it, with hose, or

otherwise, until twenty-four (24) hours before it is to be covered with

the pavement surface.

=38. Measurement of Concrete.=—Concrete will be measured and computed in

cubic yards as found completed on the street, the thickness being taken

as ... inches. The contract price for concrete foundation covers the

cost of providing all the materials required, making, placing and

ramming the concrete, and keeping it moist for the necessary period.

FOUNDATION OF OLD PAVING STONE

=39.= Foundations made of old stone paving blocks shall be constructed

as follows:

Upon the sub-grade prepared as specified in Section 26, shall be spread

a layer of good sand to an even depth of one and one-half (1½) inches.

The paving blocks, whether taken up from the street to be paved, or

brought from other streets or storage yards, shall be cleaned of all

adhering earth, dirt and street refuse. The blocks shall then be set on

the bed of sand, on edge, perpendicular to the grade, with their long

dimension at right angles to the line of the street, in courses composed

of stones of the same width, extending entirely across and at right

angles to the axis of the street. Stones in adjoining courses shall

break joint at least two inches. Joints between courses or stones, or

along the curbstones, shall not exceed one inch in width. The stone

shall be fitted closely around manholes or other structures in the

street. The stones shall be so set in the bed of sand that after being

rammed as hereafter specified, their tops shall be at the proper grade.

After being thus set in place the stone shall be rammed with paving

rammers having wooden faces and weighing not less than thirty (30)

pounds, so as to force each stone to a good bearing in the sand below,

and to bring its top to a uniform grade, parallel to and ... inches

below the pavement datum. No stone shall project more than one-fourth

(¼) inch above the proper grade, and stones whose tops, after ramming,

are more than one-half (½) inch below such grade, shall be raised,

additional sand placed under them, and reset and re-rammed to the proper

grade and bearing. After the ramming shall have been completed, the

joints between the stones shall be filled with mortar. The mortar shall

be composed of Portland cement and sand, complying with the

specifications for these materials in Sections 29 and 30. One part of

cement and three parts of sand, by volume, shall be thoroughly mixed

dry, and then made into mortar with sufficient quantity of water to

produce a mortar of such consistency that it will just flow freely into

the joints between the stones. All the joints between the stones must be

completely filled with this mortar before it has begun to set. The

mortar filling shall be brought even with, but not above, the tops of

the stones. After the filling is thus completed, the foundation must

stand undisturbed until the mortar shall have set firmly, in no case

less than five days. The mortar must be kept moist during the period

allowed for setting.[13]

Old stone foundation will be measured in square yards, in place after

completion. The contract price includes the cost of handling and

cleaning the stone, supplying and placing the bed of sand, setting and

ramming the stone, supplying the materials for, making and placing the

mortar in the joints and watering the street while the mortar is

setting. Where stone is procured from other streets, or from storage

yards, the Contractor will be required to load, haul and unload them,

and will be allowed for this service a price of ... cents per cubic yard

for loading and unloading, plus ... cents per cubic yard for each

one-half mile, or fraction thereof, over which they are hauled by the

nearest practicable route, the measurement to be made after the stone is

set in the street, without deduction for joints.

=40. Broken Stone Foundation.=—The sub-grade for broken stone foundation

shall be prepared as specified in Section 26, except that the rolling

may be omitted at the option of the Contractor. The broken or crushed

stone shall be of hard, durable stone. The foundation shall have an

aggregate thickness of ... inches and shall be constructed in two

courses, as follows:

The broken stone used in the first course shall be of such size that it

will all pass through a screen having openings three (3) inches in

diameter, and will all be retained on a screen having openings one (1)

inch in diameter. This stone shall be evenly spread over the sub-grade

to such a thickness that after being thoroughly consolidated by rolling,

its upper surface shall be three-fourths inch below, and parallel to the

surface of the foundation when completed. It shall then be rolled with a

road-roller weighing not less than ten (10) tons until the stone is

thoroughly compacted.

The second course, composed of screenings, all of which shall have

passed through a screen with openings one inch in diameter, shall then

be spread over the first course and well raked into the voids of the

first course. It shall then be thoroughly wetted, and shall be rolled

with the ten-ton roller until the fine stone is driven into the

interstices of the first course and the whole thoroughly consolidated,

the wetting being repeated while the rolling continues. Additional

screenings shall be added and rolled in where necessary to bring the

surface to the proper elevation. When completed, the top surface of the

foundation shall be ... inches below, and parallel to the pavement

datum. No part of the upper surface of the completed foundation shall

project more than one-fourth (¼) inch above, nor shall it be more than

one-half (½) inch below the grade and contour above specified.

Gravel of a quality satisfactory to the Engineer may with his written

consent be substituted for broken stone. If of assorted sizes, such as

will compress into a mass having not more than thirty (30) per cent. of

voids, the foundation may be constructed in a single layer, graded,

watered and rolled, as prescribed above for broken stone.[14]

=41. Measurement.=—Broken stone and gravel foundation will be measured

and computed by the cubic yard in the street as completed, without any

allowance for consolidation by the roller or for settlement into the

sub-grade, the thickness being taken as ... inches. The contract price

for it shall cover the cost of supplying the material, placing it on the

street, and grading, watering and rolling it.

SHEET ASPHALT PAVEMENT

_Note._—A number of distinct varieties of asphalt are now used for

asphalt pavements, either alone or mixed. These different varieties

differ from each other quite widely in their physical and chemical

properties. Thus, in the form called “refined asphalt” some of their

properties are shown by the following table, the data for which is taken

from the second edition of Richardson’s “The Modern Asphalt Pavement.”

COMPARATIVE PROPERTIES OF DIFFERENT REFINED ASPHALTS

───────────────────────────────────────────────────────────────────────

Trinidad, Bermudez, Maracaibo, Calif. Gilsonite,

average average average of “D” average of

of two six grade, two

samples samples average samples

of two

samples

───────────────────────────────────────────────────────────────────────

Softens, degrees F. 180 165 225 132 280

Flows, degrees F. 190 175 236 151 300

Penetration at 78° F. 7 24 21 48 0

Loss, heated to 325° 1.1 3.7 3.2 1.7 1.6

for 7 hours, %.

Loss, heated to 400° 4.0 8.8 5.5 7.1 2.6

for 7 hours, %.

Bitumen soluble in 56.5 95.5 93.9 99.3 99.4

CS_{2}.

Inorganic, other than 36.5 2.2 2.9 0.3 0.5

bitumen.

Bitumen soluble in 35.6 65.6 51.1 69.6 47.2

naphtha.

Bitumen sol. in 98.7 99.0 93.2 95.7 99.8

carbon

tetra-chloride.

Fixed carbon. 10.8 13.7 17.2 17.6 13.2

───────────────────────────────────────────────────────────────────────

The practice has been heretofore, and is at the present time, to attempt

to make specifications for asphalt pavements broad enough to include all

the various varieties of asphalts, under general requirements which

shall admit these, and any new varieties that may appear on the market

suitable for the purpose, the object being to permit a wide range of

competition. This makes it exceedingly difficult if not impossible to

frame specifications that shall be sufficiently explicit and at the same

time sufficiently broad to admit these several differing materials. This

practice has been adhered to in these specifications, though in this

respect they are far from satisfactory to the author. So long as it

continues to be the policy of cities to admit these various varieties of

bitumen under the same general requirements for crude and refined

material, such objectionable specifications cannot be avoided. Even with

the great latitude now provided they exclude some materials with which

good pavements have been made.

Two remedies for this unsatisfactory condition seem practicable.

1. A city might purchase a sufficient supply of refined asphalt for its

use after asking for proposals under suitable specifications with

alternative requirements for the different varieties on the market, and

after bids are received and the samples accompanying them have been

properly examined in the laboratory, award contracts for a supply of one

or more kinds, as might seem best for the interests of the city. Stocks

of these would be delivered, tested and stored accordingly, in good time

for the season’s work. Specifications for construction with special

reference to the kind of asphalt it is proposed to use could then be

prepared, the contractors to be supplied with asphalt at the city

storage yard at a stipulated price per ton. This plan would possess a

number of advantages. A similar plan is quite commonly in use with

reference to hydraulic cement.

2. Specifications might be framed with special reference to the

properties and qualities to be possessed by the _asphaltic cement_,

permitting a liberal range as to the crude and refined bitumens to be

used in manufacturing this cement. This would be considered, at the

present time, a radical departure from well established custom, but the

author sees no reason why it should not be satisfactorily employed.

A sheet asphalt pavement is composed of two essential elements; a

mineral aggregate made up of sand of assorted sizes and mineral “dust”

and a bituminous cement. When properly compounded, manipulated and

compressed these elements make up a bituminous concrete suitable for use

as a wearing surface for streets and roads.

The character of the sand is important and we have now sufficient

knowledge from experience to specify a sand that will give,

approximately, the best results.

The bituminous cement is, however, the element of most importance, and

upon its suitability for the purpose depends very largely the utility

and durability of the pavements made with it.

It is important that this asphaltic cement shall possess certain

properties and qualities, most of which we are now able to define

satisfactorily, but others require further practical and experimental

study, and some tests not now in use would doubtless be desirable.

It is not a matter of importance what particular crude or refined

materials enter into the composition of this cement if the resulting

product is satisfactory in use. The prime requisite is a paving cement

that shall possess in a high degree the chemical and physical qualities

required for making an asphalt pavement of the best quality. If we can

devise standards and tests that will enable us to secure such a cement

we need not be concerned about its antecedents.

It would be well worth while for paving engineers and those who have

laboratory facilities to give attention to this matter. If it shall be

found practicable to define satisfactorily the qualities the cement

should possess without reference to the materials from which it is

compounded, a great advance will have been made, and our asphalt paving

specifications could not only be greatly simplified, but much greater

precision and definiteness secured.

While great advances have been made in the art of building sheet asphalt

pavements and in the framing of specifications for its construction, too

many of the specifications still in use are antiquated, indefinite and

unsatisfactory. Some of these contain requirements that, if literally

enforced, would prevent the attainment of the best results. They are

largely survivals of the time when little was known either practically

or technically of the science and art of constructing the pavements,

outside of the promoters and contractors in the business, who

consequently dictated, in a large measure, the specifications used. City

engineers were compelled to rely largely on the presumption that the

guarantee clauses of the contracts would insure good results, and

allowed the contractor wide latitude in the conduct of the work.

While there is undoubtedly much yet to learn, even by the experts, in

the matter of the materials to be used, a quite satisfactory working

basis has been arrived at, particularly as to the practical side of the

work, and a large mass of data accumulated by study and experience is

available to the municipal engineer, and the services of independent

experts is readily obtainable. There is no longer any good reason,

therefore, why the character of the materials to be used, the methods

followed, and the quality of the work secured should not be quite

definitely and fully specified in the same manner and to the same extent

as in the case of other kinds of pavement and with equally satisfactory

results.

SPECIFICATIONS

=42. General.=—Asphalt pavement surface shall be laid upon a foundation

of hydraulic cement concrete, or of stone blocks relaid, over a

sub-grade, to be constructed in accordance with Articles 26, 28, 29, 30,

31, 32, 33, 34, 35, 36 and 37.

Asphalt pavement surface shall be constructed in two courses, called the

base-course and the surface-course. The base-course may be from one (1)

inch to one and one-half (1½) inches thick, and the surface-course may

be from one (1) inch to two (2) inches thick, as shall be hereafter

specified.

=43. Crude Asphalt.=—The cementing element in asphalt pavements shall be

prepared from crude native, solid asphalts or from the proper

distillation of crude asphaltic oils.

Crude asphalts as obtained from the mines or natural deposits shall be

properly refined to drive off water and to separate foreign substances,

by melting at a temperature not exceeding four hundred and fifty degrees

F. (450° F.). Crude asphalts of the quality commonly called “glance

pitch” or “iron pitch” which do not distinctly soften at a temperature

of two hundred degrees F. (200° F.), and detached or deteriorated

material from deposits otherwise acceptable will be rejected.

=44. Refined Asphalt.=—Refined asphalt produced from native crude

asphalt shall be free from water and shall not contain an injurious

quantity of light oils or foreign matter. It shall not contain more than

four per cent. (4%) of organic matter nor more than thirty-six per cent.

(36%) of inorganic matter other than bitumen, and not more than eighteen

per cent. (18%) of fixed carbon, and not less than fifty-five per cent.

(55%) of bitumen soluble in cold carbon di-sulphide. Of the bitumen

soluble in carbon di-sulphide not less than sixty-three per cent. (63%)

shall be soluble in Pennsylvania petroleum naphtha of specific gravity

eighty-eight (88) degrees Baume at a temperature of sixty-five degrees

Fahrenheit (65° F.) and not less than ninety-eight per cent. (98%) shall

be soluble in chemically pure carbon tetra-chloride. When exposed for

seven hours to a temperature of three hundred and twenty-five degrees F.

(325° F.) in a shallow dish the bottom of which is covered with bitumen

to a depth of three-fourths (¾) inch, the refined asphalt shall not lose

more than five per cent. (5%) by evaporation.

Asphalts that are injuriously affected, in the pavement, by water (to be

determined by the test immediately hereinafter described), shall not be

used except under the conditions specified in Section 45. Cylinders made

from the surface mixture it is proposed to use, one (1) inch in diameter

and two (2) inches long, compressed to a density of two and one-tenth

(2.1), when immersed forty-five (45) days in ten (10) times their volume

of rain-water, shall retain a sound surface, unchanged and uncorroded by

the action of the water.

Refined asphalts resulting from the distillation of crude asphaltic oils

will not be accepted unless the distillation shall have been effected by

the use of suitable apparatus, at a temperature not exceeding seven

hundred (700) degrees F. The bitumen must not be over-distilled and “cut

back” by adding oil. The product, to be acceptable, shall possess the

following qualities: It shall melt and flow at a temperature not below

one hundred and forty (140) degrees F., but below a temperature of one

hundred and eighty (180) degrees F., and when tested in the standard New

York State closed oil-testing apparatus shall not flash at a temperature

below four hundred and fifty (450) degrees F. When exposed in a shallow

dish, the bottom of which is covered to a depth of three-fourths (¾)

inch with the bitumen, to a temperature of four hundred (400) degrees

F., for seven (7) hours, it shall not lose by evaporation more than

seven (7) per cent. by weight. Not less than ninety-eight (98) per cent.

shall be soluble in cold carbon di-sulphide, and not less than

sixty-five (65) per cent., nor more than seventy-five (75) per cent. of

the bitumen shall be soluble in cold Pennsylvania naphtha of gravity

eighty-eight (88) degrees Baume. Not less than ninety-nine (99) per

cent. of the bitumen shall be soluble in carbon tetra-chloride, and it

shall not contain more than sixteen (16) per cent. of fixed carbon.[15]

Bitumens resulting from destructive distillation or from artificial

oxidation, and bituminous compounds prepared from oil or oil residuums

heated with sulphur or other substances, or coal or gas tars, will not

be accepted, nor shall they be mixed with the asphalt used.[16]

=45.= Asphalts that are injuriously affected by water, and those whose

practical value for making pavements has not been established, in the

judgment of the City, by sufficient experience, will not be accepted

except under such special bond and guaranty provisions as the City may

prescribe.[17]

=46.= Full information as to the source and character of the crude

asphalt and the method of refining it shall be furnished to the Engineer

and verified by such evidence as he may require.

=47. Softening or Tempering Agent.=—For softening and tempering refined

asphalt, petroleum residuum oil or liquid asphalt shall be used. It

shall be free from water, coke, and other impurities. Its specific

gravity shall not be below 0.92, nor above 1.04. Its flash test

(determined in the standard New York State closed oil-testing apparatus)

shall not be under three hundred and fifty (350) degrees F., and when

exposed for seven (7) hours to a temperature of three hundred and

twenty-five (325) degrees F., in a shallow open dish, the bottom of

which is covered by the oil to a depth of three-fourths (¾) inch, it

shall not lose more than five (5) per cent. by evaporation. It shall not

contain more than ten (10) per cent. of paraffine scale.

=48. Sand.=—A superior quality of sand will be required and this must be

secured, if necessary, by the admixture of two or more sands. The sand

shall be silicious and so free from organic matter, mica, soft grains,

and other impurities, that these shall not aggregate more than two (2)

per cent. of the mass. The grains shall, preferably, be moderately

“sharp” or angular, and must be of assorted sizes so that the voids in

the compacted mass of dry sand shall not exceed thirty three (33) per

cent. A typical sand, to be approximated as closely as practicable, will

give the following sieve tests, the sieves being used in the order

named:

3 per cent. of the whole will pass No. 200 sieve.

15 per cent. of the whole will pass No. 100 sieve.

18 per cent. of the whole will pass No. 80 sieve.

30 per cent. of the whole will pass No. 50 sieve.

24 per cent. of the whole will pass No. 30 sieve.

10 per cent. of the whole will pass No. 10 sieve.

and none will fail to pass the No. 10 sieve.[18]

=49. Pulverized Stone.=—This may consist of limestone or other sound

stone or sand, pulverized to such fineness that the whole will pass the

No. 50 sieve, not more than ten (10) per cent. will be retained on the

No. 100 sieve, and at least seventy (70) per cent. of it will pass the

No. 200 sieve. Portland cement may be partly substituted for pulverized

stone, where the Engineer shall so direct.[19] Portland cement thus used

will be paid for at the price bid per barrel for the same, in addition

to the price paid per square yard for the pavement surface. The

pulverized material must be thoroughly dry when used.

=50. Asphaltic Paving Cement.=—Asphalt Paving Cement shall be prepared

from the refined asphalt described in Sect. 44 and the tempering agent

described in Sect. 47. The refined asphalt, together with the asphalt in

the tempering agent, shall constitute not less than sixty per cent.

(60%) of the asphaltic cement.

The refined asphalt and the tempering agent shall be mixed and melted

together at a temperature not below two hundred and seventy-five degrees

F. (275° F.), and not above three hundred and twenty-five degrees

Fahrenheit (325° F.), and thoroughly incorporated by agitation until a

homogeneous cement is produced. The agitation shall be continued until

the cement is used.