The San Francisco call. [volume] (San Francisco [Calif.]) 1895-1913, 1895-05-25
GOOD STREET PAvEMENTS,
Bernard BienenfeId Tells How
San Francisco May Be
Improved.
CONCRETE AND AsPHALTUM
Processes and Tests for Material to
Be Used on Highways In
This City.

Bernard Bienenfeld of this City has re.
Gently returned from tour of inspection
through Eastern cities, where he made it
his business to critically examine the
latest improvements in the construction of
street pavements. Mr.. Bienenfeld is well
qualified to perform this work, as he is a
graduate of the college of Civil Engineer
ing, University of California, and has for
several years been connected with the most
extensive street-paving interests of the
Pacific Coast, with special advantages fol-
observing local conditions and require
ments. He has devoted much thought to
the subject, and is acquainted with and in
correspondence with the principal paving
aut horities of the country. Speaking OF
this important subject, now so prominent
ly before the public mind, Mr.. Bienenfeld
said: "Y ears ago the larger cities of this
country and of the Old World had to meet
the same problem that now confronts San
Francisco. More rigorous climatic oondi-
lions, however, forced them to adopt
rational principles in pavement construc-
ton earlier than has been the case with US.
We may therefore learn much from a study
of their methods.
"As the result of an actual inspection of
this branch of the public service in New
York, Washington, Buffalo, Boston,
Chicago, st. Louis, Kansas City, Denver
and other progressive cities of the Union.
l shall endeavor to give such pertinent
conclusions as are warranted by the con-
dltions that exist in San Francisco.
There is nothing to prevent our adoption
OF sensible methods at once. An enfight-
ened public opinion fostered through an
enlightened. public press will certainly
prove sufficient to secure immediate re-
forms needed, now that attention has
been awakened. The construction of a
comprehensive system of underground con-
dults Tor water, gas and electric service is
no doubt desirable improvement-one
that should precede any general remodel
Ing OF our payements. And without ques-
ton the organization OF properly quail
ned Board of Public Works is consum-
nation devoutly to be hoped for. But if
we are to await the realization of these
hopes before putting down any pavement
we may long wait IN vain. AT the same
time we must not lose sight of the less
pressing, yet none the less necessary, gen.
eral reforms, chief among which is that of
the law.
cat the bottom of the whole trouble is
the law. The Supreme Court of this State
has practically held as illegal any bid for
public work wherein contractor proposes
to guarantee and maintain his work in re-
pair. The contractors only incentive for
doing honest work is thus withdrawn. 1t
becomes his highest motive to perform his
work as poorly and cheaply as possible, to
barely meet the exactions of Improper
spec1hcatlons. After having once received
his pay he has no further interest in the
durability of his pavement.
Nearly all of the large cities of this
country and OF Europe require from the
paving contractor an effective guarantee,
extending over period of from five to fif-
teen years. This guarantee is usually
coupled with nominal charge for main
tenance after the first five years. The re-
suit OF that system is that the contractor is
spurred on by every consideration of self
interest to do the very best work possible.
He realizes that only by so doing can he be
enabled TO maintain his work for the long
period of time fixed in his contract.
why the constituting of our law upon
this head should be so Numerically op-
posed to the dictates of public wisdom I
am unable to say. 1t is one of our most
crying evils, and until that matter and our
general street law are ompletely reformed
II will be idle to expect any generally good
street work. The drafting and enactment
OF new street law, after proper study by
qualified lawyers and engineers. is an
urgent necessity. The glaring defects of
the present cumbersome law should be cor
rected and simple method adopted for
securing honest work. The anti-guarantee
decision OF the Supreme Court must be
modified or reversed, and we must be
enabled to exact guarantees for main
tenance OF the pavements from those who
construct them. For the present, however,
no immediate reform of this law is pos
slble, although it is not too early to begin
preparing the matter for the next Legisla-
ture. The subject should be borne in mind
and acted on as soon as possible.
in regard to matters of actual pavement
1c 10 IL IL.
there is no mystery in the principles of
street-payement work. 1t is mere mat
ter OF commOn-Sense, and when stripped
of its technical verbiage readily appeals
to the Judgment of any Intelligent person.
L would here suggest that it is the duty of
every citizen, OF every property-owner and
taxpayer, of every horseman and every
wheelman, to familiarize himself with
these simple principles to the end that
each AID every person should be able to
discern whether or not any particular
piece of work is being properly DONE
Eternal vigilance is the price of good
streets, as 1t is of many other good things
FIRST comes the standardization, by
which is meant the natural ground or the
prepared bed upon which the pavement
structure proper is to be laid With us
this is usually sand. After being exca-
waited to the proper depth the sub-founda-
ton is wet and then thoroughly rolled and
c0mpacted. In the East 1t is usual to en-
ploy steam rollers weighing at least $50
pounds for each inch in width; but owing
to the extremely heavy traffic conducted
on San Francisco's streets double this
weight should be used here. Even then
the weight will hardly equal the pressure
that is sometimes brought on the finished
pavement surface by some of our loaded
trucks.
CATER the sub-foundation has been ex-
cavated and trimmed to proper contour
and thoroughly rolled, a foundation of
concrete is laid. As matter of fact, this
foundation is the pavement, the usual
bitumen or basalt- block covering being
merely the wearing surface. Too much
importance cannot be given to this con-
sideration.
'The concrete must be thick enough to
readily diffuse any extreme and unequal
load that may come on it at any one point,
to that extent acting both as girder and
arch. For light residence streets four
inches in thickness is sometimes allowed.
For most of our streets six inches will be
the minimum, and for our heaviest bust
ness streets no less than eight or nine
inches should be used. At the same time
we must be careful not to err on the side of
excessive strength; for by so doing we
may increase the cost so much as to pro-
hibit the work entirely in some instances