THE SIGNAL BOX

OVERSEAS

BACCHUS MARSH
A traditional signalling installation in Victoria

by John Hinson


A general view of Bacchus Marsh from the southBacchus Marsh is an intermediate station on the outer suburban line to Ballarat from Melbourne. In comparison to the frequent electric inner suburban services, trains here run approximately hourly and about fifty percent of these terminate here. Surprisingly, a good proportion of these trains are locomotive hauled which justifies the retention of the layout here for run-round and train storage purposes.

The line through this station was originally the main line between Melbourne and Adelaide. The track is of the "broad gauge" of 5' 3", which is what has led to the reduction in status of the line, for the interstate routes have been harmonised to 4' 8½" and their services now use a different line. A steep upgrade is encountered by trains passing through Bacchus Marsh as they climb up to the plateau. In main line days this used to rule the load manageable by the pair of 4-6-0 steam locomotives that powered the Overland service to Adelaide.

This is the view a driver would have as he approaches from the Melbourne direction in the Down direction. Through lines are numbered 1 to 5 from right to left - No1 is a loop serving the single platform, whilst No2 (the straight route) is what would be described in the UK as the "Through" line, for traffic not calling at the station. Nos 3 to 5 are sidings to the left. The signals are described below.


Bacchus Marsh signal cabinBut first we'll have a look at the signalbox.

The box, opened in 1890, compares well in design with the UK boxes built by McKenzie & Holland (see Ystrad Mynach South for an example) although it is taller than most examples. This may be purely to command a good view of the north end of the layout above the roof of the station buildings.

A good number of Australian boxes built to the design of McKenzie & Holland had extra timberwork in the gable ends which was mainly decorative. Many, such as Bacchus Marsh, have lost these during renewal or repair. A surviving example is illustrated at Kooyong.

Although the box seems to be in sound condition, the corner posts are in poor shape at the bases despite signs of previous repair. This is probably the work of the same wood-eating insects that the signals at Kwinana are protected against.


The McKenzie & Holland lever frame at Bacchus MarshSteeping inside the cabin, we find a 45-lever McKenzie & Holland frame controlling the layout. Unlike the one at Kwinana, this example is of the 1873 Cam & Soldier locking type.

The working area seems very bright and airy - this is because there is (and has never been) the need for an instrument shelf. There are no signalling instruments (track circuits now protect the single lines but it would have been worked by Electric Staff at one time) and the signal repeaters and diagram are mounted above window level on the front wall.

Kim van Alkemade recalls that back in the 1970s, one miniature electric train staff instrument was still in use (for the section to Parwan) and it was located on the rear wall of the box.


The signalman's layout diagram at Bacchus MarshEvery signal box has a diagram showing the layout, of course, and that at Bacchus Marsh is in traditional style with a paper sheet framed in varnished wood.

Surprisingly, the track circuiting of the running lines is not shown on the plan. Whereas in the UK it is seen as important to indicate individual track circuits, the principle applied here is that if a lever is electrically locked when it shouldn't be, the track circuit must be occupied.

But this isn't the entire area controlled by this cabin. A panel by the rear wall controls some other crossing loops, although rather strangely one loop between the others is controlled by a separate signal box at Melton. This arrangement has been adopted because that box was able to switch out.

Clicking on the diagram image will reveal an enlarged view.


Signal repeaters at Bacchus MarshSignal repeaters are quite basic in design and convey the same ON/WRONG/OFF indications as British repeaters.

Something else here reminded me of British practice too - the use of dymo-tape to produce crude and uninspiring labels for the repeaters.

The reason it was felt necessary to build a little shelf for the right-hand repeater is not known.


The home signals from the Melbourne direction.It's time to step out of the air-conditioned signalbox back into the strong Australian heat. Retracing our steps back to the opening view on this page, the home signals from the Melbourne direction are a fine example of the combination of lattice post and somersault signals.

This picture could almost have been taken in the UK fifty years ago, although maybe the calling-on signals would not have been placed quite so close to the arms above them. The only thing to give away the age of this photograph is the relay cabinet near the foot of the post, and the graffiti on it.

The higher arms apply to the through (No2) line and the lower arms to the platform (No1) road. The disc signal bracketed out from the main post reads into No3-5 sidings.


Close-up view of calling on arm and electro-mechanical replacer.A closer view of one of the calling-on arms reveals a couple of features of interest. The spectacle shows no light when in the on position, and an amber light when off. This is quite different from British principles.

Below the arm, the oblong cast box houses an electromagnetic automatic replacement mechanism (a "reverser"), activated by the track circuits to replace the signals to danger promptly after the passage of trains.

Although the lampman's ladder appears to only serve the calling-on arm, the main arm above would be within reach of the small crows nest behind the arm.


Starting signals towards MelbourneThe home signals towards Melbourne from the through (No2) and platform (No1) lines are mounted beside each other on a bracket. The disc on the main post signals trains into the headshunt (called Siding C) to the left. A turntable is accessible from here; this is still in working order and sees occasional use for steam specials.

Notice how the signal is inclined at approximately 45º. Whilst this matches UK practice for normal upper and lower quadrants, British somersault signals were generally operated to a near-vertical position for "off".

As this signal is not located at the extremity of the loop, another home signal has been provided for the platform line to allow the loop to accommodate trains of the loop's maximum length. This signal is misleadingly located adjacent to the headshumt, and can be made out against the background of foliage.

* - in British terms, these are starting signals, but in Australia all signals that protect points are known as Home signals.


Rear view of the advanced staring signal, with set back disc from headshuntHere is a closer view of the home signal mentioned above. Viewed from the rear, you can make out the casting on which the arm is pivoted.

Just a couple of feet down the post, a disc signal reads for trains in the opposite direction - those coming out of the headshunt onto the platform line.

Once again, a modern steel equipment cabinet contrasts somewhat with this signal from another era.


Shunt signals for departures from the sidings towards MelbourneAlongside the signals viewed above are signals leading from the sidings (lines 3, 4 and 5). Here, two shunt discs are provided. The left disc read to the main line and the right signals trains onto another headshunt alongside the single line known as Siding A.

The discs are of the old-fashioned revolving type, showing a red face and light to the driver for the "on" indication, and swivelled round through 90º (showing a green light at night for "off". Signals of this type in the UK were virtually extinct by 1970.

Have you noticed how all discs shown so far are mounted high up on conventional signal posts? This is no coincidence for ground signals are "simply not the done thing" in Victoria, featuring only at locations where space is limited.


Three discs mounted on a single postReading from another headshunt at the Ballarat end of the station called (how did you guess?) Siding B are three shunt discs mounted on a more modern post constructed from four steel girders welded together by small plates.

Here, there are three signalled routes, and the signals read as follows:

15 Top left To No1 line (platform) left route
22 Lower left To No2 line (through)) centre route
26 Top right To Nos 3-5 lines (sidings) right route

The signal numbers on the posts do not relate to the lever numbers.

This method of arranging multiple signals on a single post was also common on the Taff Vale Railway in Britain who were also the only significant user of somersault signals outside the Great Northern Railway. The discs to the left of the post apply to the left-hand route at the points, and any to the right refer to the right-hand route.


Point indicator at Bacchus Marsh.The one kind of signal that can be found at ground level is a Point Indicator. Connected directly to the rodding working the points concerned, it revolves through 90º to show different combinations of a read and green stripe to drivers. The side on which the green half applies indicates the direction for which the points are set.

This example is a modern device, consisting of reflective material mounted on a lightweight metal box. This box is in fact bolted over a rather older point indicator. The older ones featured a lamp with red and green lenses.

The necessity for this signal is not clear. It is a very recent provision, apparently added at the request of train crews. As can be seen above, the three-disc signal clearly shows which route has been cleared for the train concerned, so there really should be no need for this signal. Dare one suggest that the train crews do not fully understand the function of the signal?


Point detection equipment.Point detection equipment differs substantially from UK practice.

Clearing the signal rotates the disc which locks the points. One interesting feature is that the detectors are rigidly connected to the points by point rodding. The detectors consequently move slightly closer to the points when it is cold and slightly further away when it is hot; this prevents the detectors getting out of adjustment during temparature changes.


Starting signals towards BallaratThe home signals towards Ballarat are mounted alongside each other on a bracket signal, in similar style to those already seen at the other end of the station. The disc signals below read from each line to the headshunt (Sidings B).

Here you can see a revolving disc showing "off" - the right-hand disc has been turned away from the driver to indicate that he may proceed. The route is set for a locomotive that has brought in an arrival from Melbourne to run into the headshunt in order to run-round the train.

Beyond here, the line climbs for ten miles at 1 in 48. Some time in the mid to late 1980's, a runaway loaded ballast train, hauled (or "resisted") by a B class Diesel Electric (Co-Co 1500 hp. dual cab full body), came to grief in the yard after a perilous frightening ride down the incline, demolishing much of the point rodding at the Ballarat end of the yard. The loco and the first three wagons made it throught the points, but the rest came off and resulted in a pile of bogieless wagons. This happended about midday on a week day, but the platform road was, remarkably, again open for traffic late in the evening for the Ballarat service. Just about every car in the car park had a smashed windscreen from all the flying ballast, and the sound of the crash was heard over a mile away, but fortunately no-one was hurt.


Home signals from the Ballarat directionTrains arriving from Ballarat meet a similar arrangement of home and calling-on signals as those from Melbourne, although the lower arms here are on the left for the lower-speed connection into the platform loop.

Notice the circular white discs fitted behind the arms which are presumably intended to give drivers a better view of the signals. In the morning, the sun would have been directly behind these signals so these may have assisted with the viewing at that time of day.

Just beyond the signal is an automatic level crossing with lifting barriers.

And that concludes our tour of Bacchus Marsh, save for some light amusement below.


The train now standing . . .The 1308 from Melbourne has just arrived, and the signals have been cleared for the service (which today has limited capacity owing to a shortage of rolling stock) for the return journey.

Only joking! An engineer's inspection vehicle has arrived from the Melbourne direction. It is provided with raiseable flanged wheels to allow it to run on the track.

The signals had been cleared in the other direction as the locking fitter to was servicing and overhauling the locking.


Oh, it's gone . . .After a quick stop to chat with the signalman, the vehicle moved off towards the level crossing where it paused momentarily before suddenly driving off down the road.

I suppose I would get used to the idea eventually.

All of the traditional signalling at Bacchus Marsh is now gone and replaced by three-aspect colour-light signalling as part of the Regional Fast Rail project. The whole Ballarat Corridor from Sunshine to Ballarat is now controlled by area controllers at Ballarat using a mouse and computer screen displays.

Additional notes by Dean, David Langley, Richard Schurmann and Kim van Alkemade


Comments about this article should be addressed to John Hinson