REAL. ESTATE
AND
NEW YORK, MAYiie, 1914
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SUB-SURFACE STRUCTURES IN NEW YORK
Assessed Values For Franchise Purposes Aggregate About $500,000,000
—^About 3,800 Miles of Conduits and Mains in Manhattan Alone
.â– â– lit
By CHARLES N. GREEN*
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PART I.
FEW people, including engineers,
realize the importance of under¬
ground structures' in our everyday life,
and the need for making a more intelli¬
gent use of underground space. The
reason is that the increase in the num¬
ber and variety of public utilities has
been so great and so rapid that they are
now lying in confusion beneath the
street surface in the congested districts
of the larger cities.
As illustrating the importance of sub¬
surface structures, I might say that the
assessed value for franchise purposes of
the utilities occupying the streets of New
York City is about $500,000,000, and the
companies owning these structures are
capitalized at about twice this amount.
This, of course, includes neither the
water and $24,000,000 for sewer systems,
which are municipally owned and oper¬
ated, nor street paving, which is largely
affected by structures beneath it.
In Manhattan alone there are nearly
500 miles of street, with over 1,400 miles
of gas mains, over 900 miles of water
mains, and nearly 500 miles of sewers
of all kinds', and over 1,000 miles of
trench for high and low tension electric
service.
The laying and maintaining of street
structures constitute one of the serious
problems which confront the distribu¬
tion department of all companies and
bureaus that are compelled to use the
streets' for their distribution systems.
The importance of these structures is
only brought to our attention when
something goes wrong—either our wa¬
ter supply is temporarily cut off, our
sewers clogged, gas pipes are frozen,
or some accident has occurred and our
telephone, electric light or subway is'
temporarily out of commission.
The needs of primitive man were few,
very few, indeed, and until he began to
herd together in camps, little but his
personal needs occupied his attention.
When he began to build a permanent
home, and his own tribe, clan, family
or those with a common interest built
near him, it became necessary to have
adenuate water supply, and to dispose of
bodilv and camp or town wastes. In his
further development, the higher he rose
in civilization, the greater became his
necessities, both actual and those which
contributed to his convenience and lux¬
ury, and after the water and sewers
there followed artificial light, means of
transportation for the community, heat,
telegraph, telephone, refrigeration, pneu¬
matic tubular despatch, compressed air
or hydraulic pressure for ventilation or
power. It was a wise town which an¬
ticipated its future needs both in the
general plan of its streets and in their
width. The lack of such fnrcsiu'ht has
inspired the present day and generation
with the idea of city planning as a meas¬
ure tending to economy, convenience
and be.iuty.
Water was the first necessity, and we
find the Greeks and Romans building
•Lecture delivered at meeting of American
Society Enelnecrs, Architects and Constructors,
in United Engineering Building, May 12,
DO YOU appreciate the extent and
scope of the sub-surface improve¬
ments in New York City? The en¬
tire municipality is honeycombed
with pipes and wires, all having their
uses, and playing a vital part in daily
life. The Record and Guide pub¬
lishes today the first installment of
an article by Charles N. Green deal¬
ing 'with this subject and showing
the construction of these various im¬
provements and their groviring needs.
Millions of dollars have been invest¬
ed by private corporations as well
as the city in sub-surface work. One
of the difficulties encountered is that
not only must present-day require¬
ments be complied with but pro¬
visions must be made for years to
come, in order that the highways
will be undisturbed. The engineer¬
ing difficulties encountered are also
dealt 'with in Mr. Green's article.
extensive systems of water supply long
before the dawn of Christianity. Euro¬
pean and American cities have followed
in later times much the same plans used
by the Greeks and Romans. The supply
of water for New York City was first
from wells, but about the year 1800
pipes were laid by the Manhattan Water
Company to supply the city with water.
These pipes were logs of wood, bored
out and reinforced at each end with an
iron band driven into the end of the log.
First Water Supply.
In most cases' the municipality has
built, owned and operated its own water
and sewer systems, but there are many
places where both are still owned and
ooerated by private companies. The
reverse of this condition is true of
nearly all the other public utilities.
The first gas mains were laid about
1823. The gas and water pipes of this
early date had shallow hubs and were.
cast horizontally, â– differing from_ the
present day practice. Some of this old
pipe is still in service in the city. The
water pipes are still laid with poured
lead joints, which until recently was
also true of gas pipes. Gas pipes now
are more generally laid with lead wool,
which makes a joint that is less liable
to leak. Water pipes 20 inches' and larger
in diameter should be laid with air cocks
at high points', and a blow-off at low
points; gas mains should drain to drips
which are pumped out periodically.
The first sewers were built about 200
years apro, but nearly all of them have
'been built since 183S. They were built
in the center of the street, so that they
could be easily reached from either side,
unless the streets were so wide that the
laterals cost more than enough to bal¬
ance the cost of another sewer. In the
case of water and gas mains the cost
of house service is so much greater that
in most instances' mains have been laid
on both sides of the street.
Franchises were granted to so many
gas companies, each restricted to a small
area, and in most cases overlapping or
covering the same territory, that in
some streets there were, ten years ago,
five or six companies owning mains on
both sides of the same street. Today it
is not uncommon to find three com¬
panies in the same street, each with
mains large enough to supply the total
demand. Besides these service mains
there are in various streets large supply
or distribution mains and pumping
mains. These only feed the service
mains or run from the works to a
holder, or from holder to holder, and
serve to maintain the required pressure.
Advent of the Horse Car.
Horse cars were the first public con¬
veyances occupying a permanent posi¬
tion in the streets. Whether or not the
rails consisted of strap iron on wooden
stringers, I do not know, but such con¬
struction was used in some cities. Some¬
times the ends of the straps would be¬
come loose, curl up, and perhaps run up
through the bottom of the car, to the
p-reat inconvenience and danger to pas¬
sengers. The next development was, I
believe, the cable, with a great deal of
underground construction for sheave-
pits, etc. Then the overhead trolley
superseded many horse car lines, and
the underground trolley superseded the
cable. The underground trolley was, I
believe, first used in this country in
1895 and 1896. It had formerly been
used in Budapesth, but has been modi¬
fied to suit climatic conditions here. Its
underground construction is simpler
than the cable railway. In the construc¬
tion of the Broadway subway a wheel-pit
was encountered at Houston street which
extended from the cable buildin.g to the
east side of the easterly track, thus tak¬
ing up more than half the street. This
pit was about 20 feet below the street
surface to the floor, and was used as a
wheel-pit to turn the cables coming
from the basement of the cable build¬
ing which was used as a power house.
The latest development has been the
storage battery cars, but the street work
of the track does not differ materially
from that used for horse cars. There
are in the city many miles of track on
which cars are not operating for pas¬
sengers, but solely to hold down the
franchise. They occupy space which
could be used to far better advantage.
Steam Pipes Installed.
About 1880 the first steam pipes were
laid under the streets of New ^'ork.
These pipes are of wrou,ght iron and
vary from 4 to 20 or 24 inches in diam¬
eter. Originally they were laid in
wooden logs, and later in a brick con¬
duit with a wooden cover and the space
around the pipe filled with mineral wool.
In the modern form the pipe is covered
with air cell coverin.?. The conduit is
built of hollow tile and the space filled,
a.s' before, with mineral wool. Instead
of a plank top, half a sewer tile is used,
making an arched roof. On account of
the need of expansion joints, valves,
and to prevent radiation of heat
street surface, these
placed deep in