Image TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage TileImage Tile
Image size: 7168x8704 Scale: 55.00000000000001% - PanoJS3
Page overview thumbnailicon minus sign

Article text

Fix this text
View0text corrections for this article
View all articles on this page Previous article Next article
Sat 23 Sep 1911 - The Southern Argus and Wagin-Arthur Express (Perth, WA : 1905 - 1924)
Page 5 - Cutting Out the Zig=zag.
Cutting Out the Zig=zag.
A REMARKABLE RAILWAY ENGI-
NEERING FEAT IN THE BLUE
MOUNTAINS OF NEW SOUTH
WALES-SPENDING £300,000 TO
IMPROVE 5£ -MILES OF LINE—
WHAT THE "CUT-OFF" WILL
SAVE.
(By Arthur Norton, in tilie "World's
Work.")
When Australia first fell a victim to
conqueist by the Iron Horse, itihie engineers
-of New South Wales were confronted
with a stern resistance on the
part of Nature. As the steel thread
was driven .inland the Blue Mountains
barred (the way, and their subjugation
presented <a pretty problem. Like
«veiy mew coumtiy in the iJuoes of
early development, this State did not
possess a flourishing exchequer, while
the population was scattered in small
communities. Under such circumstances
railway building had to be carried
out upon, the most economical
dines, and the result wia-s that- steep
grades and sharp curves were unavoidable.
But harassed <as he was by lack of
fluids, and driven to extremities to
•provide ta road, -ihe engineer achieved
a. pdeoe of work which for difficulty;
and audacity has ranked <as one of the
foremost engneering feats of the Antipodes.
This is the "Great Zigzag"
-whereby -the Great Wiestem line o^eroom.es
.-the Blue Mountains.
When it became imperative to cross
(this range in order to connect Penrith
to Bothuist in 3J861, the controversy
that .raged around the proposal was
extraordinarily fierce. It was freely
maintained that the ideia was absolutely
impossible owing to the forbidding
character of the (mountain cliffs
ait "the proposed point of crossing.
Mr. John Whitton, M.Inst.C.E., the
•engineer-in-chief. hammered away ia>t
Kibe project until at last in sheer despair
-the authorities lelented, but the
Kinportumate engineer wtas warned that
construction was not to cost more than
£20,000 per mile! As -the only obvious
solution of the difficulty was by means
of 'heavy tunnelling, such <a limit in
expenditure was quite insufficient to
tenable this work to be undertaken.
Possibly -the authorities considered
4Jb.at by their decision 4ihey had cooled
the ardour of the engineer effectively.
Dead-Ends.
Such was far from being the case,
iiowever. As he could not tunnel the
obstruction .the engineer determined to
wind his way saround, and he did BO by
means of a "zigzag," winding to and
.fro up /the face of the cliff with heavy
gradients and sharp curves. When
one stood on the brink of ibhe cliffs
and peered into the ravins one could
see the railway ascending the cliff-face
on. three tiers, .the permanent way being
iaiid on a shelf hewn out of the
eolid rock.
There weie in reality two zigzags,
but the larger of the two =3$as the more
iamous, as in two places tfie engineer
could m!ot introduce a curve in order to
get from one level to the other, so
made a dead-end such .as are in iexisitenoe
on the Oroya Railway in Peru
and ithie Daijeeling Railway/in India,
tehie train being hauled along one level
and pushed along ithe one above, to
revert to pulling when the topmost
level was attained.
_
In this way thieengm-eer lifted the
metals about six -hundred feet in five
and hialf miles, and as may be sealis©!
ithe banks were of exceptional steepness,
and certainly were too adverse to
a large volume of traffic or speed.
As the prosperity of the State developed,
the preisencdl of this Zigzag
reacted more and mlore seriously upon
ithe economical operation of the railway
Matters were relieved somewhat
by cutting out the smaller zigzag about
iweny years lago by driving a tunnel
through the *aicli 'the mudings
followed. Then the curves "were eased
somewhat except on the Great Zigzagwhich
such was absolutely out of the
question except at prodigious cost
involving complete reconstruction.
A Chain of Tunnels.
In 1908 -the traffic had grown to
2 585,000 ions per annum, and it was
obvious that- something must be done.
The realignment of the railway
through the mountains had been discussed
for some years past HI® more
or less academic manner, but when Mr.
Henry M.Inst.C.E., assumed
the position of Engineer-in-Chief to
!the Government Railways, (he pusned
tfxe matter so energetically and actively
forward that it was decided to cut
n
m
b
m
q
p
t
A
l
h
m
i
9
c
out the zigzag once and -for all. tie
liiad investigated the problem thoroughly,
and had elaborated a survey I e
ougliiy, ana itaa " A | e
which offered the ^
"
practical solution.
The subject was
threshed out, and at last tihe
cutoff
was sanctioned.
In
the re-alignment
the
engineer
took advantage of «a number of spurs
running out from
the
main range.
These! he decided to tunnel, the spoil
removed from
the
excavation being
dumped into intervening valleys-
»
engineer was not provided by Mature
appreciable elbow-room in which
.to perfect his Work, as on all sides he
was surrounded by steep perpendicular
cliffs, many falling down sheer mto
ithe Kanimbla Valley for 1000ft. or
more.
Early in July 1908 work was commenced
iand was pushed forward with
vigour. Within a few months one
thousand men were busy at work tearing
out rock iamd soil from cuttings
and preparing for the attack on the
spurs, through \
tomels were to be <*riven_ Owing to j
the inaccessibility . position, .
S S ^ t S f i J f c X & S S ; '
among -these preliminary works was a
funicular railway, whereby the old line
and the new works was rendered accessible
by the men.
A Huge Blast.
Though ithe cutis were heavy the
more important work was m connection
with the tunnels, and no time
was lost in crowding
pwaches to the wails of the clife. The
rock itfhlait stood in the way was blasted
oST in huge masses. In one casea
shaft with a T-drive was sunk practically
to the level of the tmck. This
wS ioaded with 4£ tons of biasing
powder and 1251b of gdigmte ^d fired
electridally- In this -upheaval 35.000
sbo&s of rock were displaced, and the
blast was so ctean that the tunnel face
was opened up practically by tihe one
shot.
In order to carry out the boring
operations economically a smJall powerhouse
was established to provide electric
energy up to about 750 horsepower,
a temporary transmission system
being carried over th« whole of
the works, and topped at convenient
points to operate electridally driven
air-compressors by mans of which the
rock drills were manipulated, to supply
current for driving the ventilating
fans, as well as pumps for water, and
general lighting purposes.
Owing to the -tunnelling being wholly
through sandstone lying an level beds,
the work could be excavated very true
to form, so that practically no timbering
was required to support the roof
preparatory to lining.* The arch is of
semi-circular form, with a diaaneter of
26ft. to Jaocommodate a double .line.
Blasting was cfarried out entirely by
electric detonation, as this represented
an appreciable saving in time and
avoided the risk attached to failure of
the ordinary fuse to burn to time.
Although eleven tunnels were projected,
one had to be abandoned in
favor of an open cut. as the spur
through which it- passed was found to
be badly shattered. The result is ifcfaat
the line' passes through what may be
described as a huge ditch, with the
bank sloping upon either side fat one
point to a height of 132ft. Still, the
driving of an open cut was found to
be cheaper than running a tunnel
through broken beds of stone, inasmuch
as the latter would have demiandied
heavy timbering and lining.
What the "Cut-off" Saves.
The -effect of the new line upon traffic
may be gathered from .the fact that,
whereas on the old zigzag the gradients
were 1 in 40, they are 1 in 90 on the
cut-off. Curves also are easier, being
of 924ft. radius as complared with
528ft. radius on the original line. The
extent of the new work agggegates
6 miles 2585ft. of double lines, which
shows a saving of 66ft. on the abandoned
section. The length of tunnelling
requisite was estimated at 2991
feet, but this was reduced by the
elimination of one of the short tunnels
as already mentioned.
Iii order to influence the sanction of
rtzbis undertaking, some interesting details
were advanced at the inquiry to
show the urgent necessity of the deviation
and what it tvouM mean to the
railway deparlftierft It was pointed
out that 19GHJ >Soir t 5188 goods ttfamns
passed over ^fe n igzag in the course
of the year. f the zizzag were
eliminated 5 ts anticipated, if the
traffic ramai—. at that figure, that it
might <be possible to reduce this number
by as mJamy as 1200 trains. The
drawback to the old line was that the
dead ends of the zigzag were too short
to carry <a large number of complete
goods trains. Many had to be divided
at one end of the zigzag, pushed <amd
pulled up m seobions, and re-united
when tiie top was gained. Then its
existence also militated against speed,
and it was shown, that with -the proposed
cut-off no less than 686 hours
could be saved every year with the
passenger trains, while it was expected
that- something like 50 per cent, would
be Saved in the running expenses.
So energetically .was the task pushed
forward that within ten months 410,000
cubic yards out of an estimated total
of 466,009 icuSic yards in the cuttings
were excavated, one land a half miles
of permanent way were prepared,
single line laid, and 1430yds. of tun-
elling were completed. It was estiated
that the cost of the work would
e £265,000, but it has approached
elarer £60,000 per mile, and conseuently'ranks
as one of the most exensive
pieces of railway engineering
hat 'has ever been completed in the
ntipodes.
Built by Day Labor
w
w
p
f
T
The work was carried out by diay
abor, the working day being of eight
ours, for which the men received
inimum wage of 8s, while the miners
n the tunnels received from 8s 6d to
s -per day, the more skilled labor reeiving
wages proportionately higher
The work, though designed by the
ngineer-in-cliief for railway construction,
has been carried out by the
ncrineer-Mi-chief - - - for - existing " --- lines,
James FraSer, M.Inst.C.E., the
7
task being an improvement upon an
existing line, and as it impinged upon J
an existing structure, it could be controlled
better by the existing lines
staff- ,
Though -the "Great Zigzag, which
-has long been one of the tourist sights
of the State, has now been relegated
to the limbo of things that were, it
has been replaced by an engineering
feat which is in every way (as remarkable.
True at lacks the spectacular
aspect, from the popular point of
view, associated with the former piece
of work, but technically it is every
whit as interesting.
That the zigzag would have to be
abandoned sooner or later was no
doubt realised by its progenitor, for he
himself in the first place recommend^
tunnelling. As the traffic increased it!
became a source of danger, though
S^tely no seriouldisaster'has eve
^ o n during ite
nappwa
demanded
S T * A , ^ ag^oajol
improve IIUU'IU * C «.!,<, V'W origin 'Q loc»i.o», « » ,1
due probably to the 'heavy cost the
re-alignment entailed.
But though the travelling public will
be deprived of a striking example of
engineering skill, the scenery that is
unfolded from the new line will constitute
more than adequate compensation.
Being built at a high level
overlooking ylawning ravines, skirting
steep -precipices. and crossing deep
gulches, superb vistas of the beauties
of the Blue Mountains, especially of
the K'aniinbla Valley and Mount York,
are secured as the train passes from
tunnel to tunnel. That- it will be a
popular route to tourists is veiy evident,
while from the nailw&y operating
point of view the money expended will
be recouped in. the great saving in the
item of "working expenses," which
upon 'this division was such a serious