The Houston daily post. [volume] (Houston, Tex.) 1886-1903, 1900-02-11

have been provided for with reference to
train service that uses only trsins o,
the usual size. but when a heavy freight
train, With the number OF cars and two
big engines is substituted for the reg.
ular sizcd train contemplated by me,han-
ical engineering in the original construc-
ton OF the road, 1t will he readily seen
that the wear and tear aud injury to the
track must be greater than the road
ought reasonably to he subjected to-"
Without going into the subject OF
stresses in bridges and culverts ii must
be patent TO any one even without techni-
cal training that no stresses can be pro-
duced IN any structure greater than those
due TO the heaviest load which the length
Of the structure win permit 1t TO carry.
Consider ordinary trestles aud culverts OF
ten TO fifteen feet opening that are found
IN large numbers on all railroads. The
length OF locomotive with its tender r.
between fifty and sixty feet The length
OF the panels or bents IN the trostlc work
OF the distance from center to center OF
the rows OF plles, Is abBit hfteen feet.
all OF the drivers OF elrsI sud ten wheel
ensincs-and the drivers, II is well known,
carry most Of the weight--are embraced In
distances of from ten 10 hftcen feet Any
bent Of trestlc work or small opening.
therefore, receives its maximum stresset
and its hardest punishment when tho
drivers Of locomotive rest on IT, Whether
there are one or two or ten locomotives
al the head end OF train. the stresses in
one unit OF the trestle work are not greater
than with one. for the ten locomotives oc-
cupy ten or moro times the number OF
benis and tho supporting units arc cor
fespondingly multiplied. On any span IN
10 the length OF locomotive and tender,
no greater stress can he Imposed than that
produced by the one locomotive. The
structure, If properly designed, should
stand repetition OF such stresses an In
definite number of times and the uassaGo
OF second locomotive Immediately be-
hind the first simply repeats the original
stress but docs not Increase It.
Suppose a structure long enough to carry
two locomotives; that is to say, bridge
from 90 30 100 feet in length Il is the
universal practice In designing such sirnc-
lures and has been the practice for many
wears lalthough the writer of the article
referred 10 considers double headers an in.
novation) to design them for double. head
ers, as II was customary when cirruin-
stances required for railroads TO put two
locomotives at the head OF their trains
and bridge engineers recognized Il IN their
specifications Tho bridge specifications OF
the Pennsylf ania railroad. Baltimore and
Ohio Wabash Northern Pacific Southern
Pacific, Phoenix Bridge company, Pen.
coyd Bridge COMPANY Of Consulting Enei-
neers Theodore Cooper G. Boscarem OF
Profs. a. ] Dubois and J. y. Johnson
all prescribed the consideration Of double
headers in designing bridge structures.
From the above examples. which migN he
indefinitely multiplied u necessary n Ia
evident that proportioning structures for
double headers is not only recent but is
the universal rrnclice Of all well managed
railroads, consulting engineers, and Is
taught In all of the colleges OF the United
States.
When the structure becomes longer than
the length OF two locomotives, the speclh
cations prescribe that u is to be designe1
To carry not only the two locomotives.
but the heaviest trainload that can pos
sibly be put behind them. and that such
leading shall not tax the material beyond
one-ffth to one eighth of It's breaking
stress.
It is also stated that The rails are not
sufficiently strong Again 1t will appear
10 any rejecting person that the heaviest
stresses that ever occur IN a rail are pro-
duced when single pair Of drivers Of any
locomotive is midway between adjacent
ties One pair Of drivers 10 one loco
motive taxes rail- as heavily as any sin :
gle pair OF drivers IN any number OF
locomotives. Heavier rail is being laid
in place OF the light, because T. costs less
TO maintain. makes pieasanter and
smoother riding tracks. and because the
weight on the axles of Individual loco
motives and individual cars has been in
creased Of late yesre.
Double heading has absolutely no 10.
fiuence on the weight Of rails.
Il Is claimed that IL Is frequent oo'
currence for Drawbacks 10 be pulled out
OF cars o. the entire ends Of cars to bs
puited out by double headers, This can
not be denied but il is equally true that
drawhcads are torn out OF cars and the
headers 90 we'll IN incompetent or care
less omploye can break any train In two
by pulling out drawheads or ends Of cars
with almost any given locomotive, no mat
ter how light. and as these accidents are
auto as frequent where but one locomo-
tive is used as whcre two are used. L
makes no case against the policy Of run
ming TWO locomotives Oh a train.
As to'tho general deterioration OF track,
increased expenses, etc. the merest tyro
In railroading knows that the expense va
rles with the number OF wheels passlBR
over tho track. The joints. the weakest
part OF the track structure receive their
greatest stressec from the impact OF single
pairs OF wheels, and II 10000 pairs Of
wheels are 10 pass over given tolut in
day. II does not in the least affect rs
WEI Gnu AHNAuNA AhfHi ~
900 pass oyer in continuous string, OF in
units Of 200 100. 80 or 10 each,
TIE great bulk OF the business Of the
southern Pacific. or SunBet lines In Texas,
Is transeontlnental traffic. Certainly the
Galveston. Harrisburg aud San Antonio
can not live without il. All OF II IL car
ried in competition with the Canadian Pa
eihe. the Northern Pacific and other strong
lines extending across the continent. north
OF Texas. Those lines are free TO use
double headers. and are unrestricted In
the employment OF all facilities for cheap
ly and expeditiously moving the traffic.
Next 70 cheapness of the rate, prompt
ness Of the service Is one OF the most I'm
portant elements in the fierce competition
that prevails for this transeontinental
business. and in order for the Southern
route to get the business it must be able
10 give speed and reliability in the SER
vice. as we'll as a cheap rate.
Texas mry well feel Just pride in the
ability thus far OF its rail- lines 10 NEE;
the competition OF the sIrons Northern