New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1898-12-04
THE CHIEF ENGINEER REPORTS TO
COMMISSIONER SHEA.
SAYS THE STRUCTURE WILL HOLD MORE THAN
FIVE TIMES THE PRESENT LOAD WITH
OUT STREAMING THE CABLES TO
THEIR ELASTIC LIMIT.

capabe of sustaining more weight thai IL nv"
carries without fear of Overstraining IT, ne
saws that the Increase In the weight must hece'-
sarily come from the moving load ana tha' Tue
moving load mast be increased ten ana one"
times before the limit Of the strength OF '"e
cables is reached. But the elastic limit OF 'ne
..bles T. two-thirds of the breaking strain. and
the moving load must he Increased nve ana SIX
tcnths times in order to strain the cables even
to their elastic limit
Mr. Martins critics say that there are many
people who will share Mr.. Roebings views III
spite of the mathematical computations by
which Mr. Martin makes the Bridge capaple Oh
carrying five and slx-tenths times as much
weight as 1t now sustains.
MR.. MARTINS REPORT.
Mr. Martins report is follows
Department of Bridges. Borough Of Brooklyn is.s
Hon John l.. shea. Commissioner OF Brdges'
Dear Sir In response to your request oTS
connected with the Bridge e...
First-As to its strength and SAFETY; -, -,
The loads on the Bridge at present are maoe Wy
as follows Bridge cars ne trans are iade vegbs
four cars motor car whi c6af t fny loaded
weighing "a tons each. 81 tons. Total weight OF
r 5 i2 a9 9s' run Th a ffgs m peq hour and
they run on Is seconds Roadway they VIII De- ~
load s viii VII be ' diSri59ied over IS feet giving load
per lincal foot. for both tracks, OF 6sO POUNDS, ~
% m ,o gy a car arc spaced 2 feet apart hence
this load per linea foot is. for both road"ays' ''
The load on the carriageways is taken to be Two
continuous lines Of trucks zone Oh elC , ,oyS
each truck occupying - feet ana ".gniis 90 bere
- both roadways or liC" Pounndff oo 4e $40
the load from this source IS per h"ea' 'oo'' '''
rhc load on the promenade Is taken al 80 pounds
in his original report Of $50. that 80 pounds per
square foot IS mahimnm load oil ~ ~ Too vide
the load this source IS per neaI fooi 80
TOTAL moving load. per lnta fo1 -''tv ~ IN tho
,li ne fnF iwe OF i@vn IS .5 feet hence total
,no,.ine load I. 2 oi ooo mounds or 1852 tons.
In ~ the actual weight Of the Bridge super;
Of Expcrts, which was appointed to advise upon
the Introduction of the trolley cars upon the
Bridge. and it was found to or doit,oraI dead load
that has been added from time 10 time Is az lol-
lows: Additional new track for Bridge rsn N'iay
additional hauling cables and supporting snea ,i
electric fed and cables trolley ro aLW' tricks leiS
graph and telephone VI es ana caoes troiSy bt ND
and mail tubes $50 tons. Total dead weight anu
To OBTAIN the strain in the cable produced ~ ms ms
strain is thus found to 1894 tons The ultimate
s,renghh OF %, tb four Gables is q 200 tons Divide
his arrount hv the strain in the cable, y 2l2slf
is 70 saw the whole strain which is now -
So he increased by 3 22S tons 20 b
Inc SshIes Now sincs the weight OF the structure
cannot DO ma erialy increased. the whole increase
l, 0 ince mat is 1852 tons il follows that the
moving oa pr be g. s S 1sG mSGh OF is os
before tho limit of the strength OF the cables Is
The Ella site limit OF the cables is % Of the break,
Ing strain zoo. multiplied ny 2-3 when Is S-'So
The total moving load IS 1852 tons and this
would require to be increased 80 tines IN Grdtr 10 10
which point the metal Of the cables may be strained
Win rcgard 70 the safety Of the anchoraees it is
orlv necessary to say that during the first few
yoars Of the use Of the Bridge pom ahrh3hrasess
moved forward AT the top ABOUT nIe-sisnln ms ~
an inch buf there no movement at the bottom
rrnseion or settling together Of the tinbers under
The zoe o. the masonry OF the anchorages During
ore-"ichfh of an inch al each anchorage. SO that
any strains that have been brought upon them up
I'M. and II is not proposed to materially in
crease the loads on the Fridge
CONDITION OF THE SADDLES.
With regard to the eight saddles. careful meas
urcrlents have been made from time 10 time and
the results show that within year from the time.
tho Bridge was opened 10 public use they had all
moved toward the river about four inches In the
fourteen wears from 1851 10 1905 they had moved
from one inch to and onc-quarter inches addi-
tional. There IS nothing In this movement but
what IS normal and proper.
In July last when the ouragcously unbalanced
loading occurred the saddles moved toward the
| river from half an inch on some to two and one
half inches others. Those which moved for
with regard to the movement Of, elevated rail-
original schedule upon which they were run was
anprovsd by this dcnarment and no chang has nd
every direction from this Office has been cheerfuIy
Win regard 10 the ,roley-cars after they
entered upon the Bridge tendency was developed
run nan ,ne bad been fixed As the distance apar
they should run. Without delay the attention OF
the executive head Of the associated trolley com
| panics was called the matter and he at once
fncrea sod the number Of inspectors to five on each
roadway. and that number was on duty when the
allow the cars TO run close together as TO form
obstruction occurred near the Brooklyn tower over
the entire structure TO the Manhattan station ]
cannot tell, unless thetr Instructions Were that
thcy should not closer 70 each other than lO2
feet. and that they assumed that they might stand
III and The Gon9seGgcnt bncns Of ths l9wer
lid not I'm the slightest degree affect the strength
or safety Of the Bridge
ell condition of loading on the Bridge, In
srructions at once given 10 he inspectors
each Other nearer than 1o2 feet. In addition upon
your REQUEST. the policemen were instructed by the
for the trolley-clrs and also to prevent punching
Of teams on he Bridge IN f% %s OF oocko@es
balancing of the loads on the Bridge will here.
In conclusion. I beg to say that. in
Judgment. the Bridge ls as safe to-day as
saving tina; IT is absolutely safe that no one
need entertain for a moment any fears OF Its
vision hv this department OF everything pertaining
to the Bridge has never been relaxed, and will not
of both the elevated and trolley companies have
S more han w r6 10 tbs dc our and any the Po
ed 70 every request for assistance ResPs9s,fuIly
Chief Engineer and Superintendent.
HOSPITALS THIRTIETH ANNIVERSARY.