The Saint Paul globe. (St. Paul, Minn.) 1896-1905, 1901-05-27
STEEL BRIDGES BY THE POUND,
The Price Per Pound Is Small. but
Some Bridges weigh Many Pounds

Some Bridges weigh Many Pounds
Chicago Tribune.
Steel railway bridges, weighing perhaps
10000 tons apiece, and sold f. o. b. In
chicago at 3A TO 3A cents a pound, are
one of the anomalies of business. But
1t IS by the pound, deliver ed in Chicago
that the Burlington road system buys all
it's bridges and pays for most Of the re.
pairs to old bridges in the same way.
IniS work is all let by contract and bids
for it made by the pound The price
varies according to the market prices on
steel Three years ago bridges were
bought rs low as 1.S5 cents a FOUND. but
the range today is 81 to 3A cents a
pound. On this railway system for an
bridges not exceeding los feet ir length.
the girder pattern is used, with the frame
work liveted together. Above this iengta
tne truss pattern is required. having
steel plates drilled at the ends for coup
ling with other plates by steel pins.
Assistant, Engineer T Jordan, of the
burlington system, was asked as to rail-
way bridge building in general. I'm the
experience of the modern railroad" he
said, few bridges have had to be re-
placed in the last quarter OF a century
because they have worn out. The In
creased demands OF traffic have made
them out of date, either because they
We're not wide enough for double track
ing or because they We're not built Tor
such loads as we are now putting In
cars. In building bridges the weight ana
speed OF trains must be taken into con-
stderation 50 as to avoid slowing down
IS much as possible Take the ordinary
bridge without a draw in it for the pas-
sage of boats; no train is expected to
slow down because Of it, because that
section of track is supposed to be as
firm us any other.
Few people realize how carefully
bridges must be constructed in order to
stand. In the. margin between the ex-
tremes of heat and cold in this climate
steel bridge will expand and contract ~
Of its length. and to allow for this one
end of a bridge is hung from, a giant link
that swings TO allow for expansion at one
pier. In the trusses Of the truss bridges
the steel sections pinned together must be
within "a Of an inch il length between
the drilled holes for the pins. To ac-
complish this, each section Of steel must
be at exactly the same temperature as
the others at the time of drilling The
drills which cut them are fixed to q steel
shatt which expands or contracts ac-
cording to The atmosphere of the suOD in
which the bridge steels are kept for
drilling. These pieces are clamped to-
gether tightly and bored according to pat
tern, ipsGrirg that each picce viii be
Just the same length of me others whom
ever they are of the Same temperature
AS to iron OF steel bridges under stra 4
of traffic one Of the theories Of these
metals IS that constant strain and jarring
tend TO make them tired This is
weakening process brought about by the
crystalizing OF the molecules. making
bar much more likely to strap. In 1884
one Of this companys bridges was still
standing the Micei-eiruf O.
Burlington, 10, where 1t had stood since
1868 1t was an iron bridge, as steel
bridges were unknown at the time OF
the building of it.
'"The company decided to take out one
span Of this structure in order II test
the condition Ct the bridge irons 1t was
q costly bit Of experimenting. especially
as it proved that the iron was as good
as it was when it was put into the struc-
ture twenty-sx years before. It was in
SUCH good condition that the last piece
Of it was pat back a.d stayed there I'M
til 1t was found necessary to take the
bridge down to make way for double
tracks. On this bridge all trains had been
run slowly, not because of the bridge
but because of the draw that was in
in. A state law compeIs the stopping
Of all trains before reaching the draw OF
any bridge. and this means always that
sufficient control
LAS a matter of fact. this company has
about LOCO bridges of varying lengths in
its system. Accounts are opened with
each of them, showing total cost Of build
Ing and maintaining each one Of them.
As to bridge repairs. there are often f
hculties in putting in steel, which makes
bid by the pound inadvisa BILE. In such
cases we usually ask company to put
in the work according to specification. to
render an ftemized bill of costs. to which
10 or u per cent Is added by agreement
We know with whom we are dealing
in such matters, OF course. but 1 will
say in general that railroad bridge build
ers as a class are unusually dependable
men. Knowing how often jobbery and
trickery are exposed in the building Of
county and city bridges. this fact has
occasioned comment in many railroad cir
cles. But the observation cannot be dues
toned.
In determining just how long a bridge
can stand with safety, we do not have
many facts to draw upon As J have
said, the examination Of the old bridge at
Burlington threw no light upon the cues
ton. In the main, superficial examina-
lions are ali that can be made, giving to
safety the benefit of any doubt. In the
past most bridges have been outgrown.
instead of being worn out. but whether
this can be continued in the future is to
be questioned 1t seems to be a fact
that we are reaching the limit in locom0-
tive building, however. So long as the
tracks remain at the present standard,