Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1907-10-19

commissioners to engage an expert en-
| ;,inerr to inNcsligat" in rc g.lri to tho
! sire gthcnng Of the bridge for the
! crossing III tho clCCtrics al III" Water
! Vile & Augusta line. The commits
; sionors s"curcd the service Of J. +.
) Worcester Of Boston, who Inspected
the bri1g" and sent in the following
report:
The report Submit. Il 10y Mr.. Wor-
| ccstcr, yesterday. is as follows:
Boston, oct Is. 1907.
Railroad Commissioners If Maine, -iu-
| Gust1. Me.
| Gentlemen: The writer # the 18th
| inst. made 4 careful examination Of
| the Ticnnic bridge across tho k,nnc-
bee river at N'atcrvillc, Hith VI w
to determining tho points raised 10y
| the letter nf Heath & Andrews. when
| we return herewith, and has sine"
| tina: ti.le consulted tlc original plans
| Of the bridge made by In +. Oh =
ney. consulting engineer. and W"u Il
| report as follows:
| The brilgr, Whic. was Constructed
| in 1889. was bait Of brought iron. ana
| was designed for a load on til" road
| way floor Of loo pounds per StIi!:,.r
| foot; takiH., into consideration. also
| the effect of Wagpn-lnad Of T., tons
| on four wheels. The maximum ten
| silc unit strain under these conditions
| was allowed to reach 1000 pounds
| per square. inch, which was approXi-
mately nnc-half Of the elastic limit Of
the metal The bridge has il roadway
Is feet in width. with i sidewalk on
! each side i've feet in width.
i fAt
the purpose. both as to the section Of
main members and details of joints,
| and the craftsmanship was of the very
best; moreover. the metal work of the
bridge is in remarkable state of pre-
! servation, considering the time that
| has ELAPSED since it Was built and the
| situation in close proximity to INC
! falls With the exception of 4 few
| riiner changes which have occurred,
lit is as good today as it was When it
was built. and the changes referred
to can be easily corrected. Since the
bridge was built the load has Dccn in
creased by the addition of . three
| iEcn coGTs" "f plank on the roadway
/ and th@ Suspension of 4 i--inch cast
| iron water pipe. with its covering ana
| footWaiil hung below the floor. These
! increase in the dead weight however.
! are of no serious consequences. VITA
| the roadway as it new exists. though
! they hav" 4 hearing upon the posi-
biiity Of an increased nDor cul,acity
/ Tie plan put forward hy Heath d
/ Andr vs. for change in III" hridg"
includes increasing the width of the
roadway by four feet rinc inches.
! keeping the same Widt'l Oi sidewalk
! on each side ami running track fer
| an electric r&ilruad near /" the n,rth
curb The question referred I" us IS.
whether the bridge would b" strong
/ cna;iyi - pcrHIit this in"rt dSr IN
4 \ id;h and the carrying Of single cleo
! trio car* Weighing either ~ tons or 40
. tons We fins, tnat the increase in
width Of II" roadway, together with
| the ;:dditi@nal weight of the water
! pipe hefor, mentioned. and single
/ electric cars weighing 20 tons. and
! furt h, rnore. allowing that the dis
rrihuted load over the balance Of tn"
bridge not occupied By til" electric
car Wruid anount to 50 pounds per
square foot. instead Of the 100 pounds
a uricin:liy assumed. would inrrcaS"
the tensile unit strains in the trusScS
to ;tnout 1000 pounds ror square
in,h. anI that the same conditions
! Will. :. lotion car instead of Il :i6-ton,
! unuid increase the unit strains to
about 2G,ooo pounds per square inch.
The increases above noted are very
generally distributed throughout tn"
! bottom cl.oIds and main dagunalS Of
I The trusscE. 50 that it would =" lmr"S-
sibip 10 prevent tllcs,. strains Us any
! reinforcement Of : few paris
Tho question therefore resolves it
i self into whether it would b" safe u!-
! der the circumstances to allow unit
stresses in wrought iron as high as
/! eco pounds per square inch, or 20
0no pounds per s"u1r" inch.
! IT we could he absolutely certain
! that the loads for which We provide
could never un.,>r any circumstances
! be greater than these considered. 1t
( Nould probably be safe to allow IN"
| u.s.. of til" cotton cars With the in
creased width ii roadway. 1t would
lot "ctIn - De SAFE. however tn allow
! tne use o. the ic-ton ears under any
/ Cir~unst1 nC'&. Strains of 2o.Oo9 poundS
/ per :ui!.;r, inch III wrought iron VIII
! in t;!i!t produce II structural change In
, tie metal. causing il tn lose ITS due
tility. This result would be dangerous.
ard should prevent the use of 4o-fon
cars While the same reason does not
lold good IN the case of the 3o-ton
car: ii s,e1S t. US that the margin
4 Of safety is too small to warrant re
4 ccrstiuc ting the floor ass proposed Il
! tho tracks are laid and the roadway
. Widcucd. can any human agency
guarantee that the weight of cars will
not eventually be increased To the dam
SeroIls limit? The bridge should serve
/ for Tlany Years to come. if kept in con-
dition. and the changes in street rail
way rolling stock are 50 rapid that
| there will be the strong temptation. al
| most from the start to overload the
struct ure. We therefore are obliged to
recommend that the change proposed
be not allowed without extensive