On Wednesday, 6 February 2013 8:36 AM, Tony Prescott wrote ---

As for trams, this little difference Noel and I have over
signalling/safeworking revolves around the problem I have that tram drivers
are, in this context, treated as morons whereas bus drivers (and car and
truck drivers for that matter) are apparently highly responsible individuals
capable of making autonomous decisions as to how they control their vehicle.

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Safe operation of 'light' or 'heavy' rail vehicles is not clear-cut but
weight, speed, visibility, headway can all play a part in the choice of
signaling or not. On the SLR, higher speed than on street operation is
allowed, there are visibility issues on some sections, headway is not so
clear cut, but in my opinion, the signalling was designed for the future
when additional LRVs and branching routes could result in the need for
closer headways than now with only a small fleet of LRVs.

Several cases from my NSW railway experience where additional but never
used facilities were provided ----

1. Rhodes -- In anticipation of additional tracks from North Strathfield
to Rhodes, a new signal box was built and partly equipped near the former
Tullochs siding. The project was cancelled but the signal box remained for
a number of years only to store electric signalling equipment.

2. Sydenham --Signalling and per-way at Sydenham was expanded to cope with
the proposed additional two tracks between Sydenham and Erskineville.
Sydenham signal box was provided with additional equipment and points were
laid for a siding at Sydenham to allow for the extra tracks. In addition,
extra platforms and signal relay facilities were built at St Peters and
Erskineville. This work was carried out by the direction given to the
signal and per-way engineers. At a later stage, however the scheme was
cancelled but the evidence of this cancelled project remains.

3. Ashfield -- When the Strathfield area resignalling was under
construction, Ashfield goods siding was still busy handling 'S' trucks
loaded with coils of heavy steel (unloaded by vintage PE cranes). There
was a late request for a section of 'wrong road' signalling to permit trains
on the Down Local line to by-pass the shunting operations at the siding.
Some time later, the siding was closed, but the signal equipped for this
by-pass facility remains for all to see.

Also at Ashfield, a facing crossover and signals were provided to allow Up
Local trains to terminate at Ashfield. This facility was cancelled before
the scheme was commissioned.

4. Western NSW.-- As part of the war effort in the forties, many crossing
loops were laid complete with signalling for rail traffic between Victoria
and Queensland, avoiding the coastal route through Sydney. Many of these
loops were commissioned at considerable expense but were never used.

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Maybe the above instances will show that signal and per-way engineers obey
the directions from railway administration on facilities which are required.
I think it is unreasonable to lay the blame on the engineers if the planned
facilities are underused or never used.

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Tony also wrote --- That Hong Kong crash that shook up the signal engineers
is no different from a bus running into the back of another bus.

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Maybe so, Tony. That Hong Kong crash happened at Shan King North and was on
a sharp curve with poor visibility. Most parts of the Tuen Mun light rail
system are in the middle of streets with good visibility, where standard
traffic signals regulate both light rail and road traffic at intersections
Maybe the Shan King situation could have done with a suitable additional
warning device.

On the Adelaide busway, I don't think that there are any sharp curves with
poor visibility requiring warning of 'a bus ahead'.

The Wynyard tram tunnels were wisely equipped with signalling to avoid the
situation of a collision with a 'blacked out' tram on a curve. The Manly to
The Spit tramway had an electric warning signal for road traffic in Sydney
Road, where out bound trams entered the road from a 'blind curve'.

Noel Reed. A signal engineer who obeys the directions from above.

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