THE LAND OF REMARKABLE RAILWAY BRIDGES
In order to describe fully the complete conquest which the iron horse
has accomplished in British India, volumes would be required. In that
country the steel highway has been driven forward in the face of
prodigious difficulties of every description; the story is an exciting
romance.
But the features which impress the traveller most strongly are the
bridges. Some compel more than passing interest because of their
great length, such as the Sone bridge, on the East Indian railway,
which consists of 93 spans, giving the structure a total length of
10,952 feet, making it one of the longest bridges in the world; or the
Godavari over the river of the same name on the Madras North-East line,
9,066 feet in length; others because of their height, as, for instance,
the Gokteik Viaduct in Burma, 325 feet high; or the Dhorabhave Viaduct,
178 feet above the stream; while here and there attention is challenged
because of the massive proportions of the structure or its unusual
design, as, for instance, the Jubilee Bridge across the river Hooghly
at Naihati, or the Lansdowne Bridge across the Indus at Sukkur, the
main span of which is 790 feet clear.
It may be safe to assert that no country has offered the bridge-builder
such striking opportunities to display his ability or enterprise as
the Indian Empire. The Americans point to the great width of their
waterways, and the huge structures which leap across the Mississippi,
Missouri or Columbia rivers, but, compared beside the erections which
carry the railway across the Indian waterways, they appear puny.
The Indian rivers are famous for their great width, and the extent
to which they break up the country through which they make their
tortuous ways to the sea. The result is that when the engineer is
called upon to cross from bank to bank, especially in connection with
the more important waterways, he is faced with some teasing and complex
problems, to solve which demands often considerable ingenuity and the
expenditure of much racking cogitation. These rivers are bad friends
to the engineer at the best of times, but when lashed into fury and
swelled to flood they almost defy mastery.
The flood is the bugbear of the bridge-builder. One never knows
what the enraged water is going to do next. Sir Bradford Leslie,
K.C.I.E., M.INST.C.E., who probably has been associated with more
great engineering achievements of this character in India than any
other living engineer, can recall thrilling moments innumerable. For
instance, when he was carrying the Jubilee Bridge across the river
Hooghly, the water carried away one of the caissons which he was
about to launch for one of the piers. He thought it had been lashed
safely into position by means of chains, preparatory to sinking,
but the Hooghly “bore” quickly undeceived him. The Hooghly bore is
an ugly customer, for at times it attains a height of 7 feet, and
travels up-stream for 70 miles in four hours. This rapidly-moving
bank of liquid struck the unlucky caisson, although the latter was of
respectable dimensions and weight, snapped the mooring chains as if
they were pack-thread, and carried the cylinder away as if it were a
small butter-tub. The engineer had a lively chase up-stream after his
work, and finally secured it stranded in an awkward position about
half-a-mile above its site.
Immediately arrangements were hurried forward to salvage the caisson.
After a day and a half’s continuous hard toil it was recovered and
anchored alongside the bank until the next propitious moment arrived
for it to be towed out into the stream and sunk into position.
In the early days the engineers in their bridge-building operations
suffered the maximum width of a river to dictate what the length of
such a structure should be. Seeing that the normal channels of many of
these waterways are narrow in comparison with what they attain under
flood, this rendered bridge-work exceedingly expensive and intricate.
It is no uncommon circumstance for a waterway, when swollen by the
rains of the wet season, to spread out for a width of three miles or
more. It becomes practically insatiable, the soft earth forming the
banks falling a ready victim to the powerful eroding action of the
scurrying water. The result is worse than that brought about by the
scouring of the River Mississippi, which devours huge masses of land
continually on either bank. When the Indian river falls, unsightly
stretches of undulating sandbanks are revealed, riven by little
back channels and small lagoons, which present a general aspect of
desolation. Under such circumstances, bridging from bank to bank is a
somewhat vague undertaking, for the simple reason that it is difficult
to decide what are the limits of the waterway, because erosion
continues until the water reaches material which defies this action.
The engineer has met this situation now in an ingenious manner. He
determines the channel of the river and keeps it within bounds by means
of an artificial wall or training-bund, which is carried parallel with
the navigable channel, the flow of water through the space between
the inner side of the wall and the shore being obstructed by a solid
embankment which carries the track. This system was employed first by
Mr. J. B. Bell to carry the North-Western State railway across the
Chenab River at Sher Shah, and proved so eminently successful that it
has come into general favour.
[Illustration: THE TRAINING-BUND OR WALL TO NARROW THE GANGES BY 3000
FEET FOR THE CURZON BRIDGE, SHOWING RAILWAY APPROACH]
One of the latest and most interesting, as well as largest undertakings
of this class, is that in connection with the Curzon railway bridge
over the Ganges at Allahabad, for the Allahabad-Fyzerbad railway. At
this point the river flows between high banks of hard clay about 3
miles apart, and so resistant is this earth to scouring action that
erosion has been brought to cessation practically. The width of the
waterway, however, is about 1¼ miles, and when it was decided to
span the river, a great length of steel appeared inevitable.
[Illustration: ERECTING THE PIERS FOR THE CURZON BRIDGE
The training-bund is to be seen in the background.]
The engineer-in-chief for the work, Mr. Robert R. Gales, M.INST.C.E.,
however, decided to cut down the length of the bridge-work to 3000
feet. The project was examined at great length, owing to the fact
that the difference in the level of the river during the dry and
flood seasons is not less than 31 feet, as the Ganges receives the
waters of the Jumna about 7 miles above the site selected for the
crossing. Careful investigations, however, pointed to the fact that the
accumulated waters could be directed safely through a channel some 3000
feet wide, and accordingly the erection of the training-bund was taken
in hand on the left bank. It measures some 4000 feet in length from
end to end, and the top is 5 feet above the flood-level of the river.
The up-stream arm measures 3,300 feet in length, and the extremity
ends in a sharp curve to mitigate the effects of scouring. Viewed from
the bank, the work resembles a huge letter “L,” with the bottom arm
pointing up-stream, and the tail overhanging for about 700 feet, while
the upright member forms the embankment connecting the training-wall to
the shore, and leads the railway track to the bridge.
The training-wall is built up of sandy soil, with stone pitched on the
face exposed to the action of the river. At the top it is about 20 feet
in width, and carries a wide-gauge railway track from end to end, so
that should the floods tear a gap in the embankment, the injury can
be repaired immediately by dumping spoil into the breach from railway
wagons.
Erection had to be hurried forward, as the season available for
operations was so short. In view of the fact that the erection of the
wall entailed the handling of some 50,000,000 cubic yards of earth,
some idea of the magnitude of the task may be gathered. It was split up
into a number of contracts, and when the operations were in full swing
no less than 7000 coolies found employment.
While this work was in progress the bridge itself was pushed forward.
The length of metal is 3000 feet, divided into 15 spans, each of 200
feet, carried upon masonry piers. The bridge was called upon to meet
requirements not only for railway traffic but for pedestrians and
vehicles as well. A single line of 5 feet 6 inches gauge suffices for
the former, which is carried upon the bottom deck, while the upper deck
meets the second requisition, being 23 feet wide and about 60 feet
above the level of the waterway when in flood.
The undertaking was pushed forward with such energy that it was
completed in three seasons. The saving in outlay resulting from
constricting the river channel, and thereby reducing the length of
steel-work, represented no less than £100,000, or $500,000. This
offers a convincing illustration as to the ingenious manner in which
the bridge engineer in India has succeeded in reducing the costs of
spanning the noble waterways of the country.
In a far-away corner of the same country, Upper Burma, may be seen
another interesting example of the bridge-builder’s craft, carried out
under particularly exacting conditions in a forbidding country. This
is the Gokteik Viaduct, which carries the metre-gauge single track
of the Burma Railway Company across the gorge of the same name. This
structure was completed by the Pennsylvania Steel Company, of Steelton,
Pennsylvania, and the award of the contract was criticised severely
in Great Britain. But the Government wanted the valley spanned in the
shortest possible space of time and at a moderate price. When the
tenders invited from all parts of the world were opened, it was found
that the British firms had been outclassed by their American rivals in
both these essential factors.
The location of the railway across this gorge was beset with peculiar
difficulties. The question of the approach was trying to decide to the
best advantage, and in fact so many surveys were made that one of the
American engineers remarked “that he could not see the side of the
cliff for survey pegs.”
[Illustration: THE TRAINING-BUND UNDER CONSTRUCTION BY NATIVE LABOUR.
AT THE EXTREME RIGHT A PIER IS BEING BUILT FOR THE BRIDGE]
[Illustration: GENERAL VIEW OF THE PIER-BUILDING OPERATIONS FOR THE
CURZON BRIDGE ACROSS THE GANGES AT ALLAHABAD
The bridge is 3000 feet long. Temporary line at right.]
The gorge itself is also somewhat strange; in fact, it is a curious
wonder of Nature. The Chungzoune River flows through the rift, but
out of sight, its course being through a natural tunnel, into which
it disappears suddenly at a depth of 500 feet. When the line was
first surveyed it was in accordance with a low viaduct, the approach
thereto being over a suggested section of rack railway working on the
Abt system, with grades of 1 in 12½. This was subsequently abandoned,
and the surveyor was called upon to find a fresh location so as to
eliminate the rack railway, and to give grades not exceeding 1 in
25, so as to permit the line to be worked by adhesion. This decision
raised the height of the towers by 70 feet and increased its length to
1,350 feet. Even this did not meet with approval, for after prolonged
deliberation a third location was demanded, to give an easier line yet.
In this last survey the gradients were flattened to 1 in 40, with an
attendant increase in the height of the structure as well as of its
length. It was found impossible to improve upon the viaduct itself, so
further surveys were carried out to improve the approaches, reducing
their length and introducing curves at either end of the viaduct.
At last finality was reached, and the contract was secured by the
American bridge-builders on April 28, 1899. They lost no time in
hurrying forward the preparation of the steel. Three months later a
special train of 45 cars, laden with 977 tons, left Steelton on the
201-miles run to New York, where a specially chartered steamer was
in waiting to receive this steel cargo. The vessel left the American
port on a journey of over 10,000 miles to Rangoon, where the freight
was transferred to the small trucks of the railway and sent on the
up-country journey of 460 miles to the Gokteik gorge. No less than
three steamers were required to transport the 4,308 tons of steel,
together with some 200 tons of requisite tackle for erection, and 35
American bridge-erectors.
When the Americans arrived on the scene they were treated to their
first experience of Indian weather. The rain fell in torrents; the
roads were converted into rushing streams, and the low-lying stretches
of land into lakes. This was something new to the Americans, and
they chafed at being compelled to sit down to wait until the weather
moderated. To make matters worse, the line was knocked about severely
by the rain, no less than thirteen wash-outs occurring between the
coast and the gorge. In one place a locomotive got caught. It could
not advance and could not retreat, owing to breaches in the railway
on either side, so quietly settled down to rest in the waterlogged
embankment, and finally slipped into a field of rice, to the intense
disgust of the owner.
The result was that the port became congested with the steel and
tackle awaiting dispatch up-country. The railway company repaired the
wash-outs with all possible speed, and directly the line was opened
the material poured towards Gokteik in a ceaseless stream. In fact,
the American engineers were somewhat perplexed by the speed with which
the material was sent up, and they had a spirited task in sorting out
the pieces of steel as they arrived. The work proceeded so feverishly
that the empty trains could not be backed out of the shunting-yard
with sufficient alacrity to admit incoming loads. The bridge-builders
extended assistance in a novel manner. Shunting was abandoned. The
large steam derricks picked up the empty cars bodily off the one track,
whipped them round, and deposited them upon a siding, from which the
engines pulled them out as best they could.
[Illustration:
_Photo by permission of Pennsylvania Steel Co._]
THE GOKTEIK VIADUCT UNDER CONSTRUCTION
The railway track is 825 feet above the level of the Chungzoune River,
which flows through a tunnel beneath the bridge.]
The railway company provided the builders with a special railway down
the side of the cliff, as the approach was not completed. This was
a huge switch-back, where the trains ran from side to side, first
forwards and then backwards. The descent of the precipice in this
manner treated the bridge-builders to an exciting ride, which somewhat
unnerved them at first, as it was far and away too thrilling to be
pleasant. A cableway was also stretched across the gulch, and this
was used for transporting material from point to point. In fact, two
locomotives were dismantled and sent across this rope in pieces to
be re-erected on the opposite side.
[Illustration:
_Photo by permission of Pennsylvania Steel Co._]
VIEW OF THE GOKTEIK VIADUCT
There are eighteen steel towers--the highest brings the rails 325 feet
above the floor of the gorge--supporting 2,260 feet of bridging.]
When the bridge-builders arrived they found that Mr. G. Deuchars,
the engineer-in-chief to the railway, had completed the whole of the
preparations. The concrete pedestals for the steel towers stretched
across the floor of the ridge in two unbroken lines over the top
of the natural bridge through which the Chungzoune River makes its
subterranean way. All that the bridge-builders had to do was to set the
steel.
The viaduct was built upon the overhanging principle, in accordance
with the American practice, by means of a traveller. This was a
cumbersome piece of apparatus weighing 100 tons, with a long arm which
reached out over the gorge from tower to tower. To the native this
appliance was a source of infinite wonder. When it was pushed out to
its fullest extent, and the long arm appeared certain to lose its
balance and to topple into the ravine, they looked on with awe; and
when the Americans flew in the face of Providence, as they thought,
by venturing to the outermost point to carry out their work, they
shuddered. In fact, they never became accustomed to that traveller. Why
it did not capsize exceeded their comprehension.
The American workmen were assisted in their operations by 350 natives
brought from other parts of the country, and who were accustomed
somewhat to bridge-building. Once work was brought into swing, it went
forward with a rush, the steel towers springing up from their pedestals
to a height of 200 feet or so within two or three days. The men toiled
9¾ hours every day, and there was not a halt except when the monsoon
blew and it was well-nigh impossible to secure a foothold in exposed
positions, or when the torrential rainfall prevailed.
The white men found the heat particularly trying and exhausting. Those
perched 200 or 300 feet in the air, and fully exposed to the sun and
a temperature of 120 degrees, secured a little welcome shade under an
awning that was stretched over the apparatus. They wore the lightest
of clothing, while white pith helmets served to offer some protection
from sunstroke.
The total length of the work is 2,260 feet, and it is built up to 10
spans, each measuring 120 feet, and 7 spans of 60 feet apiece. The
girders forming the deck are supported on steel towers spaced 40 feet
apart. The height of the rails at the highest pier is 325 feet above
the floor of the gorge, and 825 feet above the Chungzoune stream. No
less than 232,868 separate pieces of steel had to be handled on the
site, and the natives had to drive 200,000 rivets to secure the fabric
together.
Owing to the remote point at which work was being carried out--10,000
miles by sea from home--an elaborate cable code was drawn up, each
integral part of the viaduct, as well as details of the erecting plant,
having a distinctive word. In addition, there were special words for
the purpose of reporting the progress of the erection to headquarters.
Every week the chief engineer cabled home a full progress report
at a cost of 5_s._, or $1.25, per word. The men were provided with
a well-equipped medicine chest, and a complete photographic outfit
constituted an important part of the organisation, photographs being
dispatched to Steelton regularly to supplement the cabled and written
report on the progress of the undertaking. Only one man was lost in the
enterprise, and this was attributable to fever produced from indulgence
in alcoholic liquor. No other fatality was recorded either among the
natives or Americans, and no serious accident marred the work, which,
bearing in mind its magnitude and character, was highly satisfactory.
The actual erection occupied nine months, work being continued
uninterruptedly through the wet season, when, fortunately, the
greater part of the annual 150 to 200 inches of rain fell during the
night. Although the viaduct is 24½ feet wide across the top, which is
sufficient to carry a double track, only one road is laid at present.
The bridge also enables pedestrians to cross from one side of the chasm
to the other, refuge platforms being provided at frequent intervals
to enable those afoot to escape being run down by passing trains. Upon
completion, the structure was subjected to severe tests spread over a
period of two months, and these proving satisfactory, the structure
was accepted by the railway authorities. The mammoth steel traveller
weighing 100 tons, and which had played such an important part in the
rapid erection of the viaduct, was demolished and sold for scrap.
By the provision of this viaduct at the selected height the track is
led to a natural ledge on the opposite cliff-face. While the viaduct
was under construction the railhead was pushed forward, the material
for the grade being transported across the valley by the overhead
cable. By the time trains were able to cross the structure, the end of
steel had reached a point some 35 miles beyond.
Although the viaduct is not so lofty as other structures of its class
in other parts of the world, yet it occupies a position of distinct
importance. Moreover, it constitutes one of the finest expressions of
this class of American work that has ever been fulfilled.