New-York tribune., 1908-10-29
gIACKWELL'S ISLAND
BRIDGE OVERLOADED
FYPERTS SUST1IN THE
TRTBUNE'S CH4RGE.
Rem0ual of All EleUated Tracks
Suggested to Reduce O0erstrain
Report Made yesterday.

The Official report Of the engineering experts
apr,ointed five months age by the Board OF Esti-
mate TO investigate the safety of the Blackwelfs
Island. or Greensboro. Bridge over the East
River. between Manhattan and Queens, was
handed yesterday 10 Bridge Commissioner stew
enson. The appointment Of Messrs. Boiler x
Hodge 10 make the investigation was the result
o. the publication in The Tribune Of a series OF
articles TO the effect that there was grave ap-
Yrehension among bridge engineers that the
structure was being dangerously overloaded
The report indicates. it is understood that not
only will the traffic carrying capacity OF the
bridge have 70 be largely reduced Dslo" thaI
epecifed in the contract for erection but con-
si5ersh1a reduction will also have 10 be made in
The dead weight Of the structure This redrc-
zion in dead weight will be obtained, it is said.
Nv doing away with the use Of the upper deck.
or floor upon which ii was proposed in the con-
tract specifications 10 place four elevated rail-
way tracks. The reduction in live load. il is
asserted will be obtained by the elimination
Of elevated railway service from the bridge alto
eethe- or by the abandonment OF other traffic
services which would impose 2 live load equal to
that imposed by the use CT the four elevated
railway tracks planned for the upper floor Of
the bridge. Under the terms OF the contract
the bridge was TO have. upon the lower floor,
four trolley tracks. two roadways for wheeled
vehicles, and upon the upper floor four elevated
railway tracks and TWO passenger walks
To give the bridge the usual factor of safety
the four elevated railway tracks upon the upper
floor viii have 10 be done away with
Commissioner Stevenson said that he expected
The report Of Professor Burr. who has been act
Ing as expert for the bridge department, in a
tew days and that until he received it he could
not discuss the subject.
Henry ". Hodge. Of the firm OF Boiler &
Hodge was seen by Tribune reporter last
night and asked if the report Of his firm on the
Greensboro Bridge had been presented TO the
Commissioner Of Bridges.
yes replied Nr. Hodge the report is in the
hands Of the commissioner
Will You give an indication Of what the find
sngs are?" Mr.. Hodge was asked.
-,l0 viii give out no information whatever"
xe2l-ed Nj Hodge. You can get anything you
want 10 know on TIE subject from the Commits
siarer ot Bridges He has the report. and it is
his privilege 10 make lis findings public"
Although both Commissioner Stevenson and
Nr Hodge refused TO disclose the findings Of the
-e7o--. The Tribune has been Informed by en-
gireers who have been able TO keep track OF
bridge department affairs that the investiga-
lion into the safety Of the bridge has disclosed
serious defects and strains vastly greater than
1hcse allowed in the Specifications
The contract called for TIE erection OF super
structure capable Of carrying maximum live
load Of 10000 pounds q linear foot, with an
AVERAGE stress Of p. 900 pounds a square inch
upon the compression members, and strain NJ
q 60 pounds a square inch upon the tension
members Owing 10 the fact that the weight
Of the bridge itself was increased from S4OHl-
90 as estimated in the original speclrcatlors'
70 l03O0O000 pounds 10 increase the traffic
csrscitv The stresses were increased so that II
-he bridge was ever subjected 10 the maximum
1--we load Of 1900 pounds a linear foot called
for n the contract. with the usual allowances
t,- wind the stress upon the compression mem
he's would be 5000 pounds a square inch ana
TIE strain upon the tension members oo'V'O
pounds z square inch
The extent TO which these stresses are in ex-
cess n what is regarded as safe for such
s---,-rtre is best indicated by the fact that lhe
oartilever bridge at Quebec failed Win d s'ieSS
Of 1900 pounds a square inch upon Its compress
sim roer1rers and that the elastic limit ot the
structural steel Of which most of the tension
members Of the Greensboro Bridge are mace l5 l5
given by engineering authorities at Zo'VoO
I,ounds square inch.