Los Angeles daily herald., 1886-01-07
STREET TRAFFIC.
An Important Paper by Captain
y. v. Greene Read Before the
society of Civil Engineers.

y. v. Greene Read Before the
society of Civil Engineers.
At a meeting of the American Society
ef Civil Engineers, held last week at the
rooms Of the society, No l27 East Twen-
ty-third street, New York, Cap
tain +. V. Greene, of the United
States Engineers, read sn inter.
esting and important paper giving
the results OF exhaustive observations
upon the extent and character OF street
araffic 10 the United States as influenced
by the character Of the pavements, the
width Of the streets, etc. The paper
directed attention to the large sums in
vested In street pavements, amounting
to about $3.50, 900. 900 in the twenty
principal cities of this country, to the
desirability of keeping sytematic records
OF the traffic over the various pavements
and their wear under this trafiicj and to
certain observations upon traffic recent
ly made under the writer's direction.
After referring to the observations made
by Haywood and others in London, by
Deacon in Liverpool, and by the French
engineers In Paris, the writer described
In detail the manner in which his own
ODAeTNutlOuH were bhhcus III DiiciJ thSJ
were first recorded by one or more OBJ.
servers by the punch and trip.slip method
in use by car conductors. slips of differ
ent colors being used for vehicles OF diff
ferent tonnage. A summary OF each
hours observations was then transferred
TO daily report made on printed form.
These were sent to the writer. by whom
the computation Of total tonnage, ton
mage per vehicle and tonnage per foot OF
width we're made. The observations
were continuous from 7 A. NJ. to P. NJ.
on six consecutive days at each place.
The accidents to horses were also observ-
ed and recorded, ia three classes, viz:
Falls on knees, falls on launches and
complete falls. Record was also made
of the width and grade of street, state OF
the weather, temperature OF the air,
average speed OF the vehicles, and length
OF street on which accidents were OBJ
served and recorded. On the back OF
the printed form OF report full instruc-
tions were given for the observers, espe.
cially in regard to the weight of different
kinds of vehicles, and every precaution
was taken to have the observations made
on uniform system and to eliminate the
personal equation of the observer and
leave as little as possible to his jndg.
ment Each days report was subscribed
and sworn to by the observers before
notary public; these reports were sub
mitted to the members OF the society
present for their examination. The OBJ
servations were made on thirty-six var
ious streets in ten different cities, viz:
New York, Philadelphia. Chicago, Bos-
ton, st. Louis, New Orleans, Washing
ton. Buffalo, Louisville and Omaha.
The pavements on the streets observed
were of granite, asphalt and wood.
In compiling the results as to traffic
the standard for comparison was the
average daily tonnage per foot of width.
This was found to range from 273 tons
on Broadway in New York to seven tons
on Olive street. in st. Louis. The aver
age weight per vehicle varied from .O8
ton on Fifth avenue in New York to 2.0S
tons on a part of: Wabash avenue in
Chicago. Several remarkable instances
were given of the manner in which
smooth asphalt streets have drawn the
traffic away from stone pavements-the
most noticeable instance being in St.
Louis, where on Olive street, paved with
granite, the daily traffic per foot OF
width is only seven tons, while ON Locust
street it is 1903 tons. the two streets
being parallel, adjacent and similar in
every respect, and paved at the same
time. Comparison was also made with
the London observations, showing very
much larger traffic las high as 422 tons
on one street) in the latter city, and the
o.,,-a of tba J;ffaranoa uaa atated IN he
the absence OF street cars and the large
number of cabs and omnibusses thus
rendered necessary. Reference was also
made to the observations of Messrs.
Beacon and Stayton in England on the
comparative wear of different Glasses of
pavement nnder different amounts of
traffic as actually observed; and the de-
STABILITY of keeping such records by
municipal engineers in this country was
pointed out.
In regard to accidents the standard
or comparison was the distance travelled
before an accident occurred. This was
obtained by multiplying the distance
over which the observations were record
ed by the number of horses, and divid-
ing the product by the number of acci-
dents The general result was; On
asphalt. 5S3 miles; granite, Alb miles;
wood, 272 miles. There were only three
sets Of observations on wood, and
hence as to this class of pavement the
results are inconclusive. As to granite
and asphalt the large number OF OBJ
servations lover 800, 600 horses
and 1000 miles traveledl justified
the conclusion that fewer accidents occur
ON asphalt than on granite. This agreed
with the result of similar observations in
London, although in the latter city, from
local causes, the accidents on each class
of pavements were about three times as
numerous as in the cities observed in
America. In classifying the accidents it
was found that the falls on knees were
much more numerous on granite pave
ments than on asphalt, whereas the
falls on launches were more numer.
Gus on asphalt than on granite.
The cause of this was pointed
out, the granite blocks being too wide
(about five inches instead of three) to
afford proper footing for the horses;
and the falls on launches on asphalt be-
ing due to sudden pulling up and turn.
ing OF the horses, as noted in nearly
every case in the reports.
From Captain Greene's tables, which
are marvels of minuteness and care, it
is evident that the heaviest traffic both
in this country and in Europe, seeks the
asphalt pavement in preference to either
granite or wood; and although there are
as yet no trustworthy statistics regard.
ing first cost and maintenance, Captain
Greene favors asphalt as the universal
pavement.