New-York tribune., 1908-07-30
WANT FACTS ON BRIDGE
OPINIONS NOT ENOUGH.
Engineering Ne1cs" Calls for Tests
of BLQckreWS Structure.

Commenting editorially upon suggestion OF
Gustave Lindenthal. former Bridge Commissioner
that test should be made Of ful-sized main com
preston members of the Blackwells island bridge
in the investigation which is taking place
into the safety of the new structure over the
East River Engineering News in its issue OF
this morning says:
opened foT pubic use Until the strength Of
great compression members has been proved ny
actual test We can and shall say the ne same same
thing in stronger terms if need be; but we trust
it will not be necessary
Engineering News" also says:
We want first know more regarding that
structure than any one now knows before We Slati
nd G m e u tRe 1sb as right In can What is wanted
in IN connection wi5h the 9 TacT We said empha
icaly in commenting on the Quebec bridge dis
must be made before the engineering profession
could have full confidence in the stability and
safety of its greatest structures. We hold the
same position to-day
The suggestion which called forth this strong
preston of opinion is contained in letter written
by former Bridge Commissioner Lindenthal, who
prepared the original plans for the Backwells
Island bridge. addressed the editor of En-
gineering News The letter points out the ad-
visibility of making tests Of fu-sized members OF
the bridge ascertain their exact carrying capac-
ity rather than making tests Of models. as was
done in the of the Quebec bridge. after the
disaster had taken place. The method proposed is
not one, but was used when the construc-
tion of steel bridges was in its infancy.
II first proposed. according to Mr.. Linden
thai by Colonel Henry F1ad in 1872. during the
construction of the Eads bridge at St. Louis the
steel structure to be erected upon the CONT
nent. No testing machine is required. A stone
quarry is ell that is necessary. slot is hewn in
solid rock large enough admit the full sized
bridge member, and the test is MADE by means of
kydrostatic pressure upon punger. the rock
walls Of the slot taking the resistance. BY this
very simple and inexpensive method, Mr.. Linden
thai says pressure could be secured sufficient to
Of the Blackwell's Island bridge a cost of
few thousand dollars. The suggestion made by
Mr.. Lindenthal is strongly indorsed by En-
gineering News and the plan is pronounced en-
tirely feasible, requiring nothing than the
exercise of sound engineering and common sense
More than two months ago The Tribune brought
to the attention of the public facts which went to
show that the Blackwelrs Island bridge being
dangerously overloaded. The city bridge depart
ment at first scohed the idea, but finally con-
sented investigation being made. after Con
troler Metz had taken the initiative by declaring
that he would pass no further payments until it
was definitely ascertaned whether the structure
safe. and had appointed Messrs. Boiler and
Hodge, consulting engineers. of No. ! Nassau
street, make investigation
Since their appointment, on May 29 Messrs. Boil
Ter and Hodge have had a special staff of com
puters at work figuring the actual dead load the
bridge is carrying from the weight of material put
into it. This work il is expected will be COM
pleted about the end of next month, after which
if there is still any doubt about the meaning of
the result tests made of the carrying
strength of the main compression members to es-
tablish definitely whether they capable
of sustaining the load imposed upon them
Henry W. Hodge who has charge of the work
of making the investigation, speaking to Tribune
reporter, said that the matter of making tests Of
the large members of the bridge could not be de-
cided upon until it was ascertained what dead load
the bridge was carrying at present, and what
load ii would have to carry when completed. II
the figures showed stresses beyond the limit of
safety he would recommend that tests be made.
The suggestion made by Mr.. Lindenthal that full
size members should be tested, instead Of models,
was a good one and when the time came he would
certainly give the suggestion careful consideration