THE BORING OF THE GOTTHARD TUNNEL
The little country of Switzerland, as is well known, is a tumbled mass
of snow-clad mountain ranges. On the Italian frontier, however, this
natural barrier becomes more rugged and defiant, some of the peaks
towering 10,000 feet or higher into the clouds. For centuries this
frontier chain so successfully walled in the Helvetians that they could
not pass into Italy without making a wearisome detour. Travelling from
one country to the other before George Stephenson demonstrated the
possibilities of the steam engine running on rails, therefore, was a
journey not to be lightly undertaken, for it occupied weeks. An effort
to ease this situation was made so far back as the thirteenth century
by the blazing of a footpath over the St. Gotthard, but it was a mere
dangerous and dizzy trail. Little wonder, therefore, that it was not
favoured by other than the more adventurous.
It was not until about a century ago that the first vehicle lumbered
over this rugged hump. Then the demand for closer communication between
the two countries prompted the ambitious Helvetians to embark upon a
costly and momentous enterprise--the building of a postroad over the
mountain. They cut a roadway 18½ feet wide, with an average grade of 10
per cent. to a height of 6,936 feet up the flanks of this snow-topped
giant, with its deep rifts, rushing rivers, and faced the terrors of
the avalanche. It is a striking piece of work, for at places the road
clings, limpet-like, to perpendicular walls, describes sharp twists and
turns sudden corners. Although the people could ill afford the expense
of the undertaking, they carried it to completion, confident that
untold benefit would accrue from its provision.
They were right in their surmise. That mountain road changed completely
the direction of the stream of traffic flowing between Switzerland and
Italy. The novelty of the route, the magnificent panoramas unfolded
from every foot of its length, appealed to the tourist and traveller
and they bravely essayed the “pass.” To-day that mountain road is
trodden but seldom. It has fallen into desuetude; the railway has
killed its utility.
So soon as the iron horse invaded the little country it was sought
to carry it into Italy via the St. Gotthard; not over the mountain
crest, but through its base. Every engineer nursed the ambition to
overcome that frowning knot with the steel highway. For years brilliant
minds lived, dreamt, and died obsessed with this one great idea. Even
in 1846, when the first railway was opened from Baden to Zurich,
preparations were made to carry the line onward through the mountain
chain. To the Swiss people, boring through a mountain for nine miles or
so appeared no more difficult than burrowing through a hillock for as
many yards. It was only a question of time and expense.
An “Alpine tunnel fever” set in with terrible malignancy, and there
was fierce rivalry and jealousy created between the various railway
companies, cantons and towns as to who should have the honour of
completing this remarkable link. Fortunately the Government itself
preserved a cool head, turned a deaf ear to entreaties, refused
concessions, and discouraged any possible hope of financial aid. The
last-named factor proved the greatest stumbling-block, but there is no
doubt that if the money could have been obtained for such an enterprise
an attempt to tunnel the Alps would have been made in the ’fifties.
Though the ambition was scotched it was not killed by any means, for a
few years later the same scheme was revived and more keenly discussed
than ever. The French and Italian nations resuscitated the project
by co-operating in the effort to pierce the Col de Fréjus, popularly
known as the Mont Cenis tunnel. The first stroke of the pick-axe upon
this momentous enterprise was made in August, 1857, and the two chief
engineers, Grattoni and Sommeiller, pledged themselves to complete the
task with the assistance of the French and Italian governments. In
the face of the most terrible difficulties that could be conceived,
equipped with tools which appear puny and futile in comparison with
those used for such work to-day, they cut, blasted, and excavated
their way through 7½ miles of dense rock. Boring from either end, the
rock-hogs broke down the last wall of rock on Christmas Day, 1870, and
in September of the following year a shorter and more direct route
between the two countries was opened to traffic.
The progress of this tunnel was watched with the closest interest by
the Helvetians. This piercing of an Alpine mountain was something new
in railway engineering. The wiseacres croaked that it would never be
completed; that Nature would spring some sudden surprise upon the
engineers in the depths of the mountain which would arrest the whole
enterprise. But as the two headings slowly but surely approached one
another, and the engineers broke down their obstacles as they arose
with commendable pluck and determination, the sceptics became silenced.
[Illustration: THE GÖSCHENEN ENTRANCE TO THE ST. GOTTHARD TUNNEL
Work was commenced at this point on June 4, 1872. The huge task was
completed and the line opened for traffic on May 22, 1882.]
The pride of the Swiss was wounded. If the French and Italians could
accomplish such a herculean and apparently impossible task, why was
a similar idea beyond their powers? The “conquest of the Alps” broke
out with renewed vigour. It became more than a personal issue; it
blossomed into one of economic, political and commercial importance.
Consequently, before the Cenis Tunnel was opened for traffic, the
preliminary arrangements for burrowing through the St. Gotthard had
assumed concrete shape. But it had been a wearisome enterprise. The
promoters had to battle against intrigue and jealousies innumerable
on the part of private individuals, companies seeking for the same
concession, towns and departmental governments. But the project became
one of even more than national importance; it became an international
question. The provision of such a route would bring northern Europe
into closer touch with Italy and her ports on the Mediterranean. That
fact was realised, and when the company incorporated to carry out the
work announced that the task was far too risky for private resources,
the governments of the countries most intimately interested in the
fulfilment of the project promised tangible assistance in the form of
substantial subventions.
[Illustration: THE WONDERFUL WASSEN LOOP ON THE ST. GOTTHARD RAILWAY,
SHOWING THREE TIERS OF TRACK]
The path of the tunnel through the heart of the mountain was plotted
by Mr. M. O. Gelpke, C.E., and this in itself was a great achievement.
Fifteen stations were scattered over the mountain slopes for the
manipulation of the survey instruments, and many of these were situated
unavoidably in positions very difficult, and often impossible, of
access. Borings were made to ascertain the rock strata which would have
to be pierced by Professor Fritsch of Frankfort, and from the result of
these essential investigations it was computed that the work, including
the necessary railway line on either side of the great tunnel, could
be completed for a sum of £7,480,000, or $37,400,000. The money was
raised by guarantees of £1,800,000 ($9,000,000) from Italy, £800,000
($4,000,000) from both Germany and Switzerland, and by the issue of
shares and mortgage bonds to the extent of £2,720,000, or $13,600,000.
As a further contribution to the task, the Swiss Government undertook
to supervise actual construction.
The financial arrangements completed, the company had to search for a
man to bore the tunnel. For this purpose tenders were sought for the
whole contract. The terms of the latter were severe, as were also the
technical conditions. The tunnel was to carry a double track, to have a
height of 19.68 feet to the crown of the arch, and a maximum width of
26.24 feet, with a minimum width of 24.93 feet. The tunnel was to be
quite straight, with the exception of a slight curve at the southern
end, where, for a distance of 474 feet from the entrance, a curve of
984 feet radius was to be introduced to gain Airolo station. The rise
from the northern entrance was to be about 1 in 172 to the summit
level 3,781 feet above the sea, followed by a drop of 1 in 1000 to the
southern end. These gradients falling on either side from the centre
were necessary for drainage, and were estimated to be just sufficient
to ensure the water flowing to the portals.
Seven tenders were submitted for the enterprise, the lowest being
that of L. Favre, a well-known engineer of Geneva, who had completed
many notable railway works in Europe. He undertook to complete the
tunnel for £2,000,000 ($10,000,000) within eight years. His nearest
competitor, an Italian company, wanted twenty-five per cent. more, but
would not guarantee completion within less than nine years. Monsieur
Favre was supported by a body of influential capitalists, and the
contract was awarded to him.
Having sanctioned the project, the Government was determined that it
should be completed, and resolved that the engineer should be held to
his self-appointed time limit. The penalty it stipulated was exacting.
For every day over the ninth year Favre was to forfeit £200, or $1000,
for six months, and then double that penalty per day until completion.
A year was thus allowed over and above what he demanded to cope with
any unforeseen contingencies that might arise during the progress of
the task. Similarly, M. Favre was to receive a premium of £200, or
$1000, a day for every day he was in advance of the stipulated period.
His Italian competitor, while agreeable to the forfeit, stipulated that
it should not be enforced until after the eleventh year, which terms
the authorities refused to entertain. To ensure securing the forfeit
money should the engineer be late, Favre was compelled to deposit a sum
of £320,000 ($1,600,000) with the Government before a stone was moved.
No undertaking of such a magnitude as this tunnel, although protected
adequately by severe restrictions, ever has been carried out in the
face of so many vicissitudes; no engineer ever has been so harassed
as was M. Favre. From the moment the tender was signed and sealed
troubles commenced, some incidental to the task, others purposely
thrown in his way by jealous outside interests. In the first place,
the Government undertook, according to the terms of the contract, to
have the approaches to the tunnel completed so that he could commence
operations without delay. This was not done. Further opposition was
then encountered from another and unexpected quarter, which assumed
such proportions as to jeopardise the whole scheme. Italy, having
contributed about a sixth of the cost, and who therefore had an
important voice in the matter, demanded that half the work should be
granted to the Italian engineers who had been engaged upon the Mont
Cenis tunnel. This was a bitter question, and it took M. Favre two
weary months to adjust it.
These hindrances at last settled satisfactorily, work was commenced
on the northern side of the Alps at Göschenen on June 4, 1872, and
at Airolo, the southern portal, on July 2 of the following year. The
preliminary preparations were of a gigantic character. Though M. Favre
had sublet the constructional contract for the tunnel itself, he was
primarily responsible and nursed it as the engineer-in-chief. Huge
plants had to be installed at either end for supplying the various
demands for power for a thousand-and-one purposes. At the northern end
water turbines were laid down, driven from the river Reuss, a head
of water of 279 feet being available. At the Airolo end a similar
installation was established and operated under a water head of 541
feet from the Tremola. Subsequently, it was found that this latter
supply was inadequate. But M. Favre was a man of infinite resource.
He promptly built a viaduct 12,000 feet in length, tapping the Tessin
River, and thus overcame the water power difficulty. Small towns sprang
up at either end around the respective portals to house the machinery,
the workmen, and innumerable other details.
As tunnel-boring operations upon such a scale as this were in their
infancy, this engineer-in-chief perforcedly had to break a great deal
of new ground; to carry out considerable pioneer work. Hitherto, the
usual tools at the service of the excavators were the pick-axe,
shovel, chisel, and sledge-hammer; but such implements as these in a
work of this magnitude were akin to forging a mighty crank shaft with a
blacksmith’s hammer. New forces had to be created. The Mont Cenis had
demonstrated this fact, and in the course of its realisation a new tool
appeared. This was the mechanical percussion rock drill, operated by
compressed air at a pressure of 112 pounds and upwards per square inch.
To furnish the requisite energy to the tools elaborate air-compressing
plants had to be laid down. These were designed by Professor Colladon,
and they were capable of compressing 1,596 cubic yards of air to a
pressure of eight atmospheres every minute, the power being stored in
huge cylindrical reservoirs, not unlike mammoth steam boilers, from
which the conduits extending to the working faces on either side were
charged.
The scene in the tunnel was impressive in the extreme. At the working
face a little gallery was bored, about eight feet wide by the same in
height, at the roof of the tunnel. The drilling machines were mounted
on travelling carriages, with their perforating chisels jutting ugly
and business-like from the front. With the pent-up force of eight
atmospheres behind them, they rapped against the solid rock and slowly
but surely made a perforation. At frequent intervals there was a slight
stop, the chisel point was withdrawn and a jet of water, drawn from
a tender hauled up in the rear, was directed into the hole, when the
chisel instantly resumed its monotonous round. At intervals, a chisel,
with its cutting edge blunted from continual hammering at the iron-like
mass, was taken out, thrown on one side, and another inserted in its
place, to continue the attack on the rock. Progress was laboriously
slow, or comparatively rapid, according to the nature of the material
encountered. When the rock was of a granitic nature, then advance was
only at the rate of an inch or two per hour; on the other hand, when
soft, clayey material was tapped, then the chisels bored their way at
the rate of as many feet in the same time.
[Illustration: THE COMPRESSED AIR LOCOMOTIVE WHICH HAULED WORKMEN AND
ROCK BLASTED FROM THE MOUNTAIN IN THE CUTTING OF THE LOETSCHBERG TUNNEL]
[Illustration: WHAT THE WORKING FACE IN THE HEART OF THE MOUNTAIN IS
LIKE
The gang and drills cutting the path for the line through the
Loetschberg Tunnel recently completed.
BORING A GREAT ALPINE TUNNEL]
[Illustration:
_Photo by E. Goetz, Lucerne_]
THE LOFTY AMSTEG BRIDGE, 184 FEET HIGH, SPANNING THE MADERAN VALLEY ON
THE ST. GOTTHARD RAILWAY]
Three men attended to each machine, and by means of levers and
wheels the height of a drill could be adjusted to a nicety. Movement
was difficult, for the space was cramped. In the murky gloom the
outlines of the men could be faintly discerned. The fitful glimmer
of the oil-lamp which each carried--electric lighting had still to
be invented--fell upon their semi-nude bodies and swarthy faces.
The streaming perspiration mingling with the grime and dust, which
strayed over their skin in fantastic streaks, gave the men a fiendish
appearance. The temperature was that of an oven. As the men drew nearer
and nearer to the heart of old Gotthard, the heat rose until the men
laboured in an atmosphere of 90° or more. The only sounds were those
of the hammering of the drills as they bored into the rock, and the
hissing of the escaping air after it had completed its allotted task in
operating the chisels.
At long intervals there came a heavy silence. The holes had been bored
to the requisite depth. The machine was drawn far back into the boring.
Explosives were slipped into the holes and tamped home. From a safe
distance the charges were fired. A dull, smothered roar, a rending
and crumbling, and another gap was torn in the bowels of this monarch
of the Alps. The excavators hurried forward, cleared away the tumbled
debris, and brought the lumbering drill carriage up to the fresh
working surface.
Day in and day out, week after week, month by month, this round
continued. It was monotonous, and the work was hard. The stifling
atmosphere and the conditions told severely on the physique of the
workmen. Congestion of the brain, irregular action of the heart,
anæmia, or one of numerous other obscure maladies, was the reward for
their labour. Their faces assumed a deathly pallor; working in cramped
positions gave them an unsightly stoop, and deprived their legs of
movement, so they tottered rather than walked as they returned from the
scene of their toil at the end of the shift.
The pay was wretched, ranging from half-a-crown to five shillings
(from 60 to 125 cents) per day of eight hours, out of which they
had to board themselves! Needless to say, but few Englishmen or
western Europeans figured on the pay-roll, for none would accept such
starvation pay for such terrible work. The labourers were Italians for
the most part, and yet nearly one and all, by subsisting on miserable
food, consisting for the most part of a kind of meal porridge, cheap
and yet limited in quantity, saved a part of their earnings and sent
it home to their needy families in sunny Italy. The average number of
men employed was about 4000, half at either end, but at times it ran up
to as high as 7000. The mountain claimed 310 lives, killed by accident
alone, and 877 injured, before it was conquered; but, considering the
conditions, it is remarkable that the casualty roll was not heavier.
In the wake of the small heading gallery came the other gangs. These
rigged up the timber and other supports to the roof and excavated the
small opening to the full dimensions of the tunnel. Last of all came
the masons, setting the masonry lining, from 18 to 30 inches thick,
in position, for the tunnel is lined throughout. In passing through
the granite rock there was but little fear of a collapse of the roof,
but in the treacherous clay advance had to be made warily, and heavy
timbering resorted to, in order to prevent the soft soil caving in and
burying all in its sticky embrace.
The material for the headings and lining, as well as the workmen and
tools, were carried to and fro upon a small railway, the locomotives of
which were driven by compressed air--steam was impracticable, because
it would have fouled the workings; while on the short distance between
the inner end of the railway and the working face haulage was done by
horses. The privations suffered by the navvies was only equalled by
those experienced by the animals, the mortality of which ran up to as
high as twenty-five per cent. of the number employed.
Water was a constant menace, and at times retarded progress seriously.
On the south side it was particularly troublesome. Time after time
the drills or detonating charges would tap one of these subterranean
streams, and the water would pour out in a cascade. These rivulets were
of varying volume, but in one stretch, where the rock was extremely
friable, it was considered too dangerous to use the mechanical drilling
machine, so the men had to cut their way forward by hand. In so doing
they released a vast underground pocket of water, which rushed out
at the rate of over 3000 gallons per minute. At one spot it was only
by superhuman effort that headway was made, for the men were half
submerged in these torrential outbursts, escape from which was only
possible by penetrating farther into the mountain.
In 1876 another terrible calamity overtook Louis Favre. It was
discovered suddenly that the railway, far from costing the estimated
sum, would approximate over £11,500,000, or $57,500,000. Somebody had
blundered, and badly too. A deficit of over £4,000,000, or $20,000,000,
appeared certain. What was to be done? The development of such a
contingency never could have happened at a more inopportune moment.
Times were hard; money was scarce; financial crashes loomed in every
quarter of the Continent; and, to make matters worse, war was raging.
Never in the history of engineering had such an extraordinary and
unaccountable mistake been made in the estimates.
The discovery came as a thunderclap. The stock of the company ran
down like a thermometer plunged into ice. Those who had supported
the enterprise in the face of hostile criticism began to doubt the
wisdom of their optimism. A gloom settled everywhere. It appeared as
if the gigantic achievement would become numbered among the great
unpaid; would be another contribution to those unfinished enterprises
characterised as follies.
But Monsieur Favre kept going. There was the daily penalty staring
him in the face if he did not finish within time. Any prolonged delay
spelled ruin to him and to those who had financed his task. To make
matters worse, the Swiss departments who had the most to gain from the
completion of the railway steadfastly refused to extend the slightest
assistance.
Matters reached a crisis. Either the money must be found, or that
already spent must lie buried in the mountain. An International
Conference was called to consider the situation, where, as prominent
cities and railways who hoped to reap something from the completion
of the tunnel promised support, Germany, Switzerland and Italy agreed
to increase their subventions. Much of the projected work originally
contemplated was postponed indefinitely in order to reduce the first
cost.
This readjustment of the financial situation enabled work to be resumed
energetically. But Favre was harassed sorely still. Payments for work
became irregular, and every possible obstacle that could be placed
in his way was forced to the front by intriguing opponents. Efforts
were made even to create a rupture between him and the International
Society, but Favre’s unflagging perseverance and determination resisted
all such machinations, and he plodded along resolutely.
However, these worries and his feverish anxiety to succeed in his
enterprise told upon his health. He never lived to see his great
achievement completed. On July 19, 1879, while inspecting the progress
of the work at the headings, he was seized with an apoplectic fit, to
which he succumbed in a few hours. Literally in harness, this guiding
spirit and clever engineer passed beyond the veil when the tunnel, the
crowning effort of his life, was rapidly approaching completion.
His mantle fell upon his right-hand assistant, M. Hellwag, an
accomplished German engineer, and he pushed forward the scheme with
an energy characteristic of his late chief. But friction again rose.
Swiss engineers were jealous of this appointment, and at last in sheer
disgust the new engineer-in-chief threw up the work. He was hounded
from his post, despite the fact that on another section of the railway
he had overcome ingeniously the negotiation of sharp ascents within
short distances, which otherwise appeared impossible, by the invention
of a spiral tunnel, wherein the railway burrows into the mountain side,
describes therein a complete circle, and emerges again immediately
above the portal by which it entered.
On Saturday, the 27th of February, 1880, while the workmen on the
Göschenen side were tearing the vitals out of the peak, they were
surprised to find large masses of rock falling about their ears without
any effort on their part. They stopped. The situation seemed uncanny.
They listened intently, and then heard the familiar sound of a muffled
roar, indicating blasting in the heading. The workmen on the Airolo
side were upon them. Terrified lest the next concussion might bury them
beneath a mass of rock, they hurriedly retreated and waited. Presently
one espied the point of a chisel ploughing through the rock towards
him. He grasped its extremity, but as quickly dropped it, for it was
so hot that it burned his hand. Frantically these men rapped upon the
last remaining wall of rock to inform their comrades on the other side
that they were through. With lightning-like rapidity the news flashed
through the Göschenen workings that the men from the Airolo side might
be seen at any minute, and that the task of eight weary years was
consummated practically.
As quickly the news flashed from Göschenen to the Airolo portal to
cease work, since it was decided that the last blast tearing away the
final thickness of rock should be the occasion of great jubilation.
The whole country was excited. Officials hurried to the scene, and
the countryside from far and near flocked to the two mouths of the
tunnel. There was no sleep for any one in the constructional camps
that Saturday night. The men were in a perfect state of frenzy. In
the darkness the preparations for the culminating move were hurried
forward. It was arranged that as the men on the Airolo heading had
first pierced the last partition of rock, they should have the honour
of blowing the gap which would afford access from one side of the
mountain chain to the other through its base.
At seven o’clock on the Sunday morning a train started from each end
laden with invited guests to witness the final operation. Amid many
huzzas they disappeared into the dark, yawning mouths of the great
bore. When each party reached the heading the machines were already
at work. Only a foot of rock stood between those who had journeyed
up from Airolo and the others who had travelled from Göschenen. The
distinction of making the breach a thousand feet under the village of
Andermatt nestling in the sunshine on the mountain slopes, and with
the little lake of Sella 3000 feet above one’s head, was given to two
Piedmontese workmen, Neccaraviglia and Chisso, who had toiled in the
Cenis, and afterwards in the Gotthard, since its very commencement.
The last charges were rammed home, and at 11.45 on the Sunday morning
eight rumbling detonations heralded the piercing of St. Gotthard. Ere
the smoke had cleared away the men sprang forward. There was the final
breach, about three feet in diameter. Engineer Bossi sprang through the
gap, and emotionally embraced his confrere on the other side, followed
by his workmen, who shook hands with their comrades. It was a strange
scene in the depths of the Alps, and the wild vivas of those assembled,
to the memory of Louis Favre, reverberated weirdly down the shaft on
either side.
The excavations of the works to the full dimensions and the lining up
of the last section proceeded with great rapidity, and on May 22, 1882,
amid great festivity, the tunnel was declared open. It had taken ten
years to complete, but had Favre been left to his own devices, and had
he not been exposed to financial harassing and intrigue, and had not
his successor Hellwag been driven from his post, it would have been
finished in the time the engineer contemplated. At that time Favre’s
skill, pluck and unflagging devotion to his task were not appreciated,
but recognition of his genius was afterwards extended by the erection
of a monument to his memory at the Airolo entrance to the tunnel. It is
safe to assert that it was due to his enterprise and grim determination
in the face of adversity that the St. Gotthard tunnel became an
accomplished fact, and resulted in the reduction of the journey between
Northern Europe and Italy by thirty-six hours.
In addition to the tunnel, 172 miles of line had to be built to connect
the Swiss with the Italian railway systems. From the body of this
frowning clump 31,800,000 cubic feet of rock were torn by means of
2,200,000 pounds of dynamite.
The remaining sections of the railway named after the tunnel abound
in interesting features from the technical point of view, the most
notable, possibly, being the remarkable spiral tunnels to which
reference has been made, and the successful application of which in
this instance has been reproduced upon other railways where similar
conditions prevail. The best examples, possibly, are those by which
the Biaschina gorge is negotiated, since here there are two of these
tunnels side by side, the railway almost describing a figure 8 in
corkscrewing from one level to the other. Exclusive of the Gotthard,
there are no less than 76 tunnels and galleries, aggregating 29 miles,
as well as 1,384 other structures, 324 being bridges and viaducts
over 39 feet in length. In one stretch of 7 miles, in skirting the
south-eastern arm of the Lake of Lucerne, the railway passes through
9 tunnels, ranging from a mere 85-feet burrow to others 6,512 feet in
length. Among the Gotthard fastnesses the railway work becomes bolder,
the bridges are lofty, while the line zigzags in a remarkable manner.
It is a case of tunnel, cut and bridge all the way. Up to 1880, when
the railway was finished practically, constructional work provided
regular employment for 10,757 men.
So rapidly did the volume of traffic upon the railway swell, however,
that it became extremely difficult to handle it, as there was only
a single line, except in the tunnel and at one or two other points.
The provision of another track became imperative, and in 1886 it was
commenced. This was not a simple matter, as the new work had to be
carried out without interrupting traffic in any way--that is, so far
as the main through service was concerned. With the exception of the
Gotthard and four smaller tunnels, all the other structures had to be
excavated out to carry the second pair of metals, while, similarly,
all bridges had to be increased in width. In order to finish the work
as rapidly as possible, the task was divided up into a number of
small, separate contracts, each covering a few miles. Vehicles for the
conveyance of constructional material were provided and supplies were
hauled free of charge by the railway, while explosives for blasting
were sold at cost price.
The most difficult works were carried out by the company itself by
its own engineers and labour. In this comprehensive widening system
over 100,000 cubic yards of rock which had been excavated from the St.
Gotthard and dumped in the vicinity of Airolo were reclaimed, to be
used in the building of embankments, revetments and retaining walls.
The tunnel widening was carried out almost exclusively at night and on
Sundays, since the smoke from passing trains would have impeded such
work during the day. The quickest methods of widening were adopted,
and in the approach to the Bristen tunnel an excellent expression of
this is afforded. Instead of trimming back the mountain-side to provide
space for the second pair of rails, a gallery was built projecting
from the mountain and supported on heavy masonry pillars, giving the
appearance of a colonnade.
In the handling of unavoidable night trains an elaborate protection
system was adopted in connection with the tunnels, to prevent disaster
to the trains themselves or to the working gangs. No trains were
permitted to enter a tunnel until assurance had been made doubly sure
that there was no constructional train standing on the only line to
court collision, and that the workmen were safe. Each working squad
was covered amply by electric and other signalling devices. Similarly,
all metallic structures that required moving were handled on Sundays,
when traffic was at its lowest ebb, between the scheduled movements
of passing trains, so that the latter might not be delayed. It was
estimated that this work would occupy nine years, but in reality it was
accomplished in five and a half years, and the total cost of widening
the whole mileage to a double line was only £500,000, or $2,500,000.