The sun. [volume] (New York [N.Y.]) 1833-1916, 1915-07-25
SAFE BRIDGE
Resisting Powers Of Creosoted Wood
Blocks.

hesIstIWH IONeVS W sIVVSV'Vv
Blocks.
To THE fpIroR OF THE SuS-Sir; The
letter signed by Walter Il. kruessl call
ing the attention OF Commissioner
krackc to the III effects which might
arise should the brooklyn Bridge ne
| paved with Crcosoted wood blocks gives
an erroneous impression relative to the
~innamunabiliiy of such material.
In the attempt to draw all analogy
between the burning of the Belle Isle
hridg. in Detroit aud the possible de-
struction of the brooklyn Bridge from
the same cause should 1t he i'oorod
with cieosoted wood blocks the author
should have taken into consideration
| the fact that the Belle Isle bridge was
originally d signed for All untreated
plank door. aud when finally repaved
with crepso;ed wood blocks 1t was un-
able To withstand the additional dead
weight Of a concrete sub base, conse
uucnily II was necessary to use Greco
soted string. RS and sub~-planking.
Had the Belle Isle bridge been paved
with Creosotcd blocks over a concrete
sub-basc 1T could not have been de-
stroy.d by fire or had II had a Greco
soted sidewalk instead OF an uncreo-
soted sidewalk the probabilities are
that the flames would not have gained
much Roadway.
Contrary to the usual construction OF
"A mOderu crtOsoted wood block bridge
floor. the joists extended lengthwise OF
the bridge. and were not OF steel but OF
Creosoted 4 by ii inch southern yellow
pine timbcrs placed edgcwise and spaced
10 inches centre to centre.
Above these crcosoted joists a sub
flooring of cTeusoted 4 Inch planks was
placed. and directly upon this SUB
floor tn, creosoted wood blocks were
laid, and every third row of blocks was
,L.,.Ft.I h, thn Eph-tlln mixing and All
in,erstices between the blocks were mied
with dry sand swept in.
The only steel stringers supporting the
4 by "a inch Creusoted wood joists were
placed transversely across the bridge
about every thirty feet ~onsequenuy
after the fire secured a good start the
bridge was entirely destroyed, inasmuch
as when the creUsoted wood Joists were
burned sufficiently there were no lonsi-
tudinal steel joists to help support the
dead load of the floor, and the burning
joists and planks supporting the wood
blocks were projected into the river.
and the creosoted joists and sub-plank-
ing We're so weakened by the flames
that they gave way long before the fire
could reach the creosoted wood block
wearing surface.
thoroughly interviewed many OF the
bridge tenders and investigated the con-
ditioa OF the few spans remaining in
/ Aa'A lNAlAli'ta'ANiE 'AN'A 80 80 $500
found that It had been no uncommon
occurrence for fires to originate on the
thoroughly dried. untrelted pine side
walk OF the bridge at least a dozen
times every summer.
In such cases the fire could be traced
10 discarded cigarette or cigar stubs
lodged TIVE the finder dry planks
of the sidewalk.
These sidewalks had no foundation
and plenty of air found its way up be-
tween the int rstIces Of the sidewalk
planks and supplied the oxygen so es-
sentill To- any flame.
The most generally accepted theory
as to the origin OF the Belle Isle bridge
ire is that the strong wind carried
some Of the brands or live coal from
a tar a passing over the bridge TO
the dry Georgia pine sidewalk planklng
and scattered these brands at various
points across the bridge. These burn
ing Goals lodged in the crevices between
the sidewalk planks and We're famed
by the brisk bre re into several differ
ent blazcs. The flames then scattered
from the untreated sidewalk planks 10
rhe untrcated floor planks, toists and
sub-plauks.
In lighting his FIRE 1t was at first i'm
poss ole to account for the Coniining
OF the iiaines to the sub-structure or
underneath the bridge. The creosoted
wood block wearing surface did no,
burn. could not burn, until the joists
and sub-planking were destroyed. be
cause Of the inability of air and oxygen
q pass through the solid, mOEOiltuit
creoSotrd plauks and block floor and
before the creosoted blocks burned 70
any extent, because of the absence OF
supporting longitudinal steel girders
the blocks were precipitated into thy
river by the failure of the creosoted
, wood joists.
FIgemen lighting the flames from the
bridge surface FOUND Il necessary &c
chop hol s through the block floor and
sub-plauking before II was possible &c
insert the nozzles Of the hose in order
! 20 reach the flames underneath the
bridge.
! Thoroughly air dried creosoted tim
: b RS are not nearly so !nfiammable a,
j thoroughly air dried uutrcated tim,
/. hers, for the reason that the high boil
ing compliments of the oil do not fiasl
+ at as low a temperature as the nature
. pitch or resin of the pine timber there
fore had tn, sidewalk plank of tn
Relie Isle bridge been composed of ali
e dried yrcosotcd pine the flames woult
. probably have died In their incipiency
Il a concrete sub-base had existed tn,
: blocks could not have burned, because
: j. obviously essential fol 4 draugh
4 OF ar to supply plenty OF oxysen to a
: iucip.cut flame.
y Al example Of the uon-lnHammabilit,
of rrcosotcd wood blocks laid over con
crete suh-baS is the condition of WOO,
e block streets to-day IN the city OF Bslti
= more which successfully passed through
; tho great Baltimore fire.
; Another example OF the r~on-!nHamna
bIl.ty OF crtosotcd wood blocks place
over a conCr to suh-hasc Ia the destruc
9 ton " Pier 81, South Nharvts. Phila
. delphia, on the Philadelphia and Read
q ing Railroad, burned october II, 1871