of which the Kinzua viaduct, illustrated here, is an example. A
branch line from the Erie, connecting that system with valuable
coal-fields, strikes the valley of the Kinzua, a small creek,
about 15 miles southwest of Bradford, Pa. At the point suitable
for crossing, this ravine is about half a mile wide and over 300
feet deep. At first it was proposed to run down and cross the creek
at a low level by some of the devices heretofore illustrated in
this article. But finally the engineering firm of Clarke, Reeves &
Co. agreed to build the viaduct, shown above, for a much less sum
than any other method of crossing would have cost. This viaduct
was built in four months. It is 305 feet high and about 2,400 feet
long. The skeleton piers were first erected by means of their
own posts, and afterward the girders were placed by means of a
travelling scaffold on the top, projecting over about 80 feet. No
staging of any kind was used, nor even ladders, as the men climbed
up the diagonal rods of the piers, as a cat will run up a tree.
[Illustration: Kinzua Viaduct.]
The Manhattan Elevated Railway, about 34 miles long, is nothing but
a long viaduct, and is as strong and durable as iron viaducts on
railways usually are, while from the slower speed of its trains it
is much safer.
It may not be out of place for the writer to state here what, in
his belief, is the next series of steps to be taken to insure
safety in travelling over our bridges: Replace, wherever possible,
all temporary trestles by wood or stone culverts covered with
earth. Where this cannot be done, build strong iron or steel
bridges and viaducts with as short spans as possible and having
no trusses above the track where it can possibly be helped. Cover
these and all new bridges with a solid deck of rolled-steel
corrugated plates, coated with asphalt to prevent rusting. Place
on this broken stone ballast, and bed the ties in it as in the
ordinary form of road-bed.
By this means the usual shock felt in passing from the elastic
embankment to the comparatively solid bridge will be done away.
Has a crack formed in a wheel or axle, this shock generally
develops it into a break, the car or engine is derailed, and if it
strikes the truss the bridge is wrecked. The cost of this proposed
safety floor is insignificant, compared with the security resulting
from it.
* * * * *
The improvements in the processes of putting in the foundations of
bridges have been as great as those above water. All have shortened
greatly the time necessary, and have made the results more certain.
The American system may briefly be described as an abandonment of
the old engineering device of coffer-dams, by which the bed of the
river is enclosed by a water-tight fence and the water pumped out.
For this we substitute driving piles and sawing them off under
water; or sinking cribs down to a hard bottom through the water. In
both cases we sink the masonry, built in a great water-tight box
(called a caisson) with a thick bottom of solid timber, until it
finally rests on the heads of the piles sawn to a level, or on the
top of a crib which is filled with stone, dumped out of a barge.
Sometimes it is filled with concrete lowered through the water by
special apparatus.[6]
Another process, developed within the last twenty years, is to
sink cribs through soft or unreliable material to a harder stratum
by compressed air. This is an improvement on the old diving-bell.
The air, forced into the bell-shaped cavity, expels the water and
allows the men to work and remove the material, which is taken up
by a device called an air-lock. The crib slowly sinks, carrying the
masonry on its top.
By this means the foundations of the Brooklyn bridge and of the St.
Louis bridge were sunk a little over 100 feet below water. A recent
invention is that of a German engineer, Herr Poetsch, who freezes
the sand by inserting tubes filled with a freezing mixture, and
then excavates it as if it were solid rock.
The process of sinking open cribs through the water by weighting
them and dredging out the material was followed at the new bridge
recently built over the Hudson at Poughkeepsie, where the cribs
were sunk 130 feet below water, and at the bridge building over the
Hawkesbury River, in Australia. The Hawkesbury piers are sunk to
a depth of 175 feet below water, and are the deepest foundations
yet put in. The writer (who derives his knowledge from being one of
the designing and executive engineers of both these bridges) sees
no difficulty in putting down foundations by this process of open
dredging to even much greater depths. The compressed-air process is
limited to about 110 feet in depth.
IV.
The most notable invention of latter days in bridge construction
is that of the cantilever bridge, which is a system devised to
dispense with staging, or false works, where from the great depth,
or the swift current, of the river, this would be difficult, or,
as in the case of the Niagara River, impossible to make. The word
cantilever is used in architecture to signify the lower end of a
rafter, which projects beyond the wall of a building, and supports
the roof above. It is from an Italian word, taken from the Latin
_cantilabrum_ (used by Vitruvius), meaning the _lip of the rafter_.
If two beams were pushed out from the shores of a stream until they
met in the centre, and these two beams were long enough to run back
from the shores until their weight, aided by a few stones, held
them down, we should have a primitive form of the cantilever, but
one which in principle would not differ from the actual cantilever
bridges. This is another American invention, although it has been
developed by British engineers--Messrs. Fowler & Baker--in their
huge bridge now building across the Forth, in Scotland, of a size
which dwarfs everything hitherto done in this country, the Brooklyn
bridge not excepted.
The first design of which we have any record was that of a bridge
planned by Thomas Pope, a ship carpenter of New York, who, in 1810,
published a book giving his designs for an arched bridge of timber
across the North River at Castle Point, of 2,400 feet span. Mr.
Pope called this an arch, but his description clearly shows it to
have been what we now call a cantilever. As was the fashion of the
day, he indulged in a poetical description:
"Like half a Rainbow rising on yon shore,
While its twin partner spans the semi o'er,
And makes a perfect whole that need not part
Till time has furnish'd us a nobler art."
[Illustration: View of Thomas Pope's Proposed Cantilever (1810).]
The first railway cantilever bridge in the world was built by the
late C. Shaler Smith, C.E., one of our most accomplished bridge
engineers. This was a bridge over the deep gorge of the Kentucky
River.[7] The next was a bridge on the Canadian Pacific, in British
Columbia, designed by C. C. Schneider, C.E. A very similar bridge
is that over the Niagara River, designed by the same engineer in
conjunction with Messrs. Field & Hayes, Civil Engineers. This
bridge was the first to receive the distinctive name of cantilever.
The new bridge at Poughkeepsie has three of these cantilevers,
connected by two fixed spans, as shown in the illustration (pg.
36). The fixed spans have horizontal lower chords, and really
extend beyond each pier and up the inclined portions, to where the
bottom chord of the cantilever is horizontal. At these points the
junctions between the spans are made, and arranged in such a way,
by means of movable links, that expansion and contraction due to
changes of temperature can take place. The fixed spans are 525 feet
long. Their upper chord, where the tracks are placed, is 212 feet
above water. These spans required stagings to build them upon.
These stagings were 220 feet above water, and rested on piles,
driven through 60 feet of water and 60 feet of mud, making the
whole height of the temporary staging 332 feet, or within 30 feet
of the height of Trinity Church steeple, in New York. The time
occupied in building one of these stagings and then erecting the
steel-work upon it was about four months.
The cantilever spans were erected, as shown in the illustration on
page 37, without any stagings at all below, and entirely from the
two overhead travelling scaffolds, shown in the engraving. These
scaffolds were moved out daily from the place of beginning over
the piers, until they met in the centre. The workmen hoisted up
the different pieces of steel from a barge in the river below and
put them into place, using suspended planks to walk upon. The time
saved by this method was so great that one of these spans of 548
feet long was erected in less than four weeks, or one-seventh of
the time which would have been required if stagings had been used.
[Illustration: Pope's Cantilever in Process of Erection. (From his
"Treatise on Bridge Architecture.")]
At the Forth Bridge, all the projecting cantilevers will be built
from overhead scaffolds, 360 feet above the water. It contains two
spans of 1,710 feet each. When spans of this length are used, the
rivets become very long--seven inches--and it would be impossible
to make a good job by hand riveting. Hence a power-riveter is used
in riveting the work upon the staging. A steam-engine raises up a
heavy mass of cast-iron, called "the accumulator;" the weight of
this in descending is transmitted through tubes of water, and its
power increased by contracting the area of pressure, until some
twenty tons can be applied to the head of each rivet. One rivet per
minute can be put in with this tool.
* * * * *
It will be seen that most of the great saving of time in modern
construction of bridges and other parts of railways is due to
improved machinery. The engineer of to-day is probably not more
skilful than his ancestor, who, in periwig and cue, breeches
and silk stockings, is represented in old prints supervising a
gang of laborers, who slowly lift the ram of a pile-driver by
hauling on one end of a rope passed over a pulley-wheel. The
modern engineer has that useful servant, steam, and the history
of modern engineering is chiefly the history of those inventions
by which steam has been able to supersede manual labor--such as
pile-drivers, steam-shovels, steam-dredges, and other similar tools.
[Illustration: General View of the Poughkeepsie Bridge.]
* * * * *
After the road-bed of a railway is completed and covered with a
good coat of gravel or stone-ballast, and after all the temporary
structures have been replaced by permanent ones, that part of the
work may be said to be done, requiring only that the damages of
storms should be repaired. But the track of a railway is never
done. It is always wearing out and always being replaced.
[Illustration: Erection of a Cantilever.]
Some of the early English engineers, not appreciating this,
endeavored to lay down solid stone walls coped with stone cut to a
smooth surface, on which they laid their rails. They called this
"permanent way," as distinguished from the temporary track of rails
and cross-ties used by contractors in building the lines. But
experience soon showed that the temporary track, if supported by
a bed of broken stone, always kept itself drained and was always
elastic, and remained in much better order than the more expensive
so-called "permanent way." When the increase in the weight of our
rolling stock began to take place, dating from about 1870, iron
rails were found to be wearing out very fast. Some railway men
declared that the railway system had reached its full development.
But in this world the supply generally equals the demand. When a
thing is very much wanted, it is sure to come, sooner or later.
The process of making steel invented by, and named after, Henry
Bessemer, of England, and perfected by A. L. Holley, of this
country, gave us a steel rail which at the present time costs
less than one of iron, and has a life five or six times as long,
even under the heavy loads of to-day. We are now approaching very
near the limit of what the rail will carry, while the joints are
becoming less able to do their duty. Bad joints mean rough track.
Rough track means considerably greater expenditure both for its
maintenance and that of all the rolling stock, as the blows and
shocks do reciprocal damage, both to the rails and to that which
runs on them. Hence all railway managers are now devoting more care
and attention to their tracks.
In laying track on a new railway, if it be in an old-settled
country where other railroads are near and the highways good,
the ties are delivered in piles along the line where wanted, and
the haul of the rails is comparatively short. The ties are laid
down, spaced and bedded, adzed off to a true bearing, and the
rails laid upon them; the workmen being divided into gangs, each
doing a different part of the work. After the track is laid, the
ballast-trains come along and cover the roadbed with gravel. The
track is raised, the gravel tamped well under the ties, and the
track is ready for use.
[Illustration: Spiking the Track.]
[Illustration: Rail Making.]
The road is then divided into sections about five miles long. On
each section there is a section-boss, with four to six laborers.
Their duty is to pass over the track at least twice a day in their
hand-car, to examine every joint, and where one is found low or out
of line, to bring it back to its true position by tamping gravel
under it and moving the track. They have also to see that all
ditches are kept clear of water, a most essential point, as without
good drainage the ground under gravel ballast becomes soft, and the
mud is churned up into the gravel, and the whole soon gets into bad
order.
They have to see that the fences are all right, that trees and
telegraph poles do not fall across the track, that wooden bridges
do not burn down, that iron and stone bridges are not undermined by
freshets, and always to set up danger signals to warn the trains.
[Illustration: Track Laying.]
It is admitted by competent judges, that the track of the
Pennsylvania Railroad is the best in this country, and one of the
best in the world. It is kept up to its high standard of excellence
by a system of competitive examinations.
About the first of November, in each year, after the season's work
has been done, a tour of inspection is made over all the lines, on
a train of cars expressly prepared, consisting of two or more cars
not unlike ordinary box cars with the front end taken out. Each car
is pushed in front of an engine, and goes slowly over the line, by
daylight only, so that the inspecting party may have a full view of
the road.
The Pennsylvania road is divided into Grand Divisions,
Superintendents' Divisions, of about 100 miles long, Supervisors'
Divisions, of about 30 miles, and Subdivisions, of 2½ miles.
The examining committee for each Supervisor's Division consists of
the supervisors of other divisions. As they pass along, they mark
on a card. One sub-committee marks the condition of the alignment
and surfacing of the rails; another the condition of the joints
and the spacing of the ties; another the ballast, switches, and
sidings; another the ditches, road-crossings, station grounds.
The marks range from 0 to 10, 0 being very bad, 5 medium, and 10
perfection. When the trip is done these reports are all collected
and the average is taken for each division.
As an inducement to the supervisors and the foremen of the
Subdivisions to excel on their division, premiums are given as
follows:
$100 to the supervisor having the best yard on his Grand Division.
$100 each to the supervisors having the best Supervisor's
Division on each Superintendent's Division of 100 miles.
$75 to the foreman having the best subdivision of 2½ miles on
each Grand Division.
$60 to each foreman having the best subdivision on his
Superintendent's Division, including yards.
$50 to the foreman having the best subdivision on each
Supervisor's Division.
In addition to the above there are two premiums of honor given by
the general manager, which bring into competition with each other
those parts of the main line lying on either side of Philadelphia,
viz.:
$100 to the supervisor having the best line and surface between
Pittsburg and Jersey City.
$50 to the second best ditto.
If a supervisor or foreman of subdivision receives one of the
higher premiums, he is not allowed to be a competitor for any
others premiums, except the premiums of honor.
The advantages of these inspections and premiums are these: Every
man knows exactly what the standard of excellence is, and strives
to have his section reach it. Under the old system, a man never got
off of his own section, and had no means of comparison, and like
all untravelled persons, became conceited.
The standard of excellence becomes higher and higher every year.
Perfect fairness prevails, as the men themselves are the judges.
The officers of the road make no marks, but usually look on and see
that there is fair play.
This brings the officers and men nearer together, and shows the men
how all are working for the common good. An agreeable break is made
in the monotony of the men's lives. They have something to look
forward to better than a spree.
It is by the adoption of such methods as these that strikes will be
prevented in the future. It encourages an _esprit de corps_ among
the men, and educates them in every way.
This system was first devised and put in operation on the
Pennsylvania Railroad in 1879, by Mr. Frank Thomson, General
Manager, to whom the credit of it is justly due.
V.
I have thus endeavored to trace the history of the building of
a railway; and it must have been seen, from what has been said,
that the evolution of the railway and of its rolling stock follows
the same laws which govern the rest of the world: adaptation to
circumstances decides what is fittest, and that alone survives. The
scrap-heap of a great railway tells its own story.
Our railways have now reached a development which is wonderful. The
railways of the United States, if placed continuously, would reach
more than half-way to the moon. Their bridges alone would reach
from New York to Liverpool. Notwithstanding the number of accidents
that we read of in the daily papers, statistics show that less
persons are killed annually on railways than are killed annually by
falling out of windows.
Railways have so cheapened the cost of transportation that, while
a load of wheat loses all of its value by being hauled one hundred
miles on a common road, meat and flour enough to supply one man a
year can, according to Mr. Edward Atkinson, be hauled 1,500 miles
from the West to the East for one day's wages of that man, if he
be a skilled mechanic. If freight charges are diminished in the
future as in the past, this can soon be done for one day's wages of
a common laborer.
The number of persons employed in constructing, equipping, and
operating our railways is about two millions.
The combined armies and navies of the world, while on peace
footing, will draw from gainful occupations 3,455,000 men.
Those create wealth--these destroy it. Is it any wonder that
America is the richest country in the world?
The rapidity with which it is possible to build railways over the
prairies of the West is extraordinary. It is true that the amount
of earth necessary to be moved is much less than on the railways
of the East. In Iowa and Wisconsin, the amount runs from 20,000 to
25,000 yards per mile, while in Dakota it is only 12,000 to 15,000
yards per mile. After making all due allowance for this, the result
is still remarkable.
[Illustration: Temporary Railway Crossing the St. Lawrence on the
Ice.]
The Manitoba system was extended in 1887 through Dakota and
Montana, a distance of 545 miles. A small army of 10,000 men, with
about 3,500 teams, commanded by General D. C. Shepard, of St. Paul,
a veteran engineer and contractor, did it all between April 2 and
October 19. All materials and subsistence had to be hauled to the
front, from the base of supplies. The army slept in its own tents,
shanties, and cars. The grading was cast up from the side ditches,
sometimes by carts, and sometimes by the digging machine.
Everything was done with military organization, except that what
was left behind was a railway and not earth-work lines of defence.
Assuming that this railway, ready for its equipment, cost $15,100
per mile, or $8,175,000, and if it be true, as statisticians tell
us, that every dollar expended in building railways in a new
country adds ten to the value of land and other property, then this
six months' campaign shows a solid increase of the wealth of our
country of over eighty millions of dollars. Had it been necessary
for our Government to keep an army of observation of the same size
on the Canadian frontier, there would have been a dead loss of over
eight millions of dollars, and the only result would have been a
slight reduction of the Treasury surplus.
It must be remembered that this railway was built after the
American system: when the rails were laid, so as to carry trains,
it was not much more than half finished; the track had to be
ballasted, the temporary wooden structures replaced by stone and
iron, and many buildings and miles of sidings were yet to be
constructed. But it began to earn money from the very day the last
rail was laid, and out of its earnings, and the credit thereby
acquired, it will complete itself.
And this is only one instance out of many. The armies of peace are
working all over our country, increasing our wealth, and binding
all parts into a common whole. We have here the true answer to the
Carlyles and the Ruskins who ask: "What is the use of all this? Is
a man any better who goes sixty miles an hour than one who went
five miles an hour?" "Were we not happier when our fields were
covered with their golden harvests, than now, when our wheat is
brought to us from Dakota?"
The grand function of the railway is to change the whole basis of
civilization from military to industrial. The talent, the energy,
the money, which is expended in maintaining the whole of Europe
as an armed camp is here expended in building and maintaining
railways, with their army of two millions of men. Without the
help of railways the rebellion of the Southern States could never
have been put down, and two great standing armies would have
been necessary. By the railways, aided by telegraphs, it is easy
to extend our Federal system over an entire continent, and thus
dispense forever with standing armies.
The moral effect of this upon Europe is great, but its physical
effect is still greater. American railways have nearly abolished
landlordism in Ireland, and they will one day abolish it in
England, and over the continent of Europe. So long as Europe was
dependent for food upon its own fields, the owner of those fields
could fix his own rental. This he can no longer do, owing to the
cheapness of transportation from Australia and from the prairies
of America, due to the inventions of Watt, the Stephensons,
Bessemer, and Holley.
With the wealth of the landlord his political power will pass
away. The government of European countries will pass out of the
hands of the great landowners, but not into those of the rabble,
as is feared. It will pass into the same hands that govern America
to-day--the territorial democracy, the owners of small farms, and
the manufacturers and merchants. When this comes to pass, attempts
will be made to settle international disputes by arbitration
instead of war, following the example of the Geneva arbitration
between the two greatest industrial nations of the world. Whether
our Federal system will ever extend to the rest of the world,
no one knows, but we do know that without railways it would be
impossible.
When we consider the effects of all these wonderful changes upon
the sum of human happiness, we must admit that the engineer should
justly take rank with statesmen and soldiers, and that no greater
benefactors to the human race can be named than the Stephensons and
their American disciples--Allen, Rogers, Jervis, Winans, Latrobe,
and Holley.
FOOTNOTES: