The first coincidence

The story starts in 1977, when the Victorian Railways called tenders for 100 new air-conditioned trains for the Melbourne suburban network. Comeng Dandenong won the $108.5 million contract in 1979 with a stainless steel train with GEC traction equipment.

The first train of what are known as the ‘Comeng trains‘ was handed over in September 1981.

Weston Langford photo

A follow-on order for 90 additional trains followed in 1982, the last of which entered service in June 1989, with around half of the fleet still in service today.

Meanwhile over in South Australia, in 1983 tenders were called for 20 suburban diesel railcars for Adelaide. Both Comeng Granville and Comeng Dandenong submitted bids for various combinations of single and double-deck trains with diesel-electric and diesel-hydraulic transmissions.

In 1985 it was announced that the Comeng Dandenong design was the winner, marrying a Victorian Railways derived stainless steel bodyshell with a Stromberg diesel-electric traction package. The body shells were assembled at Dandenong and then transported by rail to Dry Creek in Adelaide for final fitout.

The first of the ‘3000/3100 class‘ railcars entered service in November 1987.

Image via Wikipedia

An additional 50 railcars being completed by Clyde Engineering between 1992 and 1996, with the fleet still being in service today.

And lighting strikes twice

In 2001 the Victorian Government called tenders for 29 2-car diesel railcars for V/Line. The $206.8 million contract was awarded to Bombardier Transportation, who had taken over the Comeng Dandenong plant through a series of corporate takeovers. The train was designed at their Brisbane offices, and was intended to follow on from their previous XPlorer train designed for NSW, but used a new bodyshell mated with a cab designed by the team behind the Transperth B-series electric multiple unit.

Dubbed ‘VLocity‘, the first train entered service in 2005.

And in the decades since, over 100 trains to the same design have joined the V/Line fleet thanks to dozens of follow-on orders.

And in 2011, the South Australia approved the electrification of the Adelaide suburban network, and needed some new electric trains to run on it. Bombardier con the contract, based on their bid combining the VLocity railcar bodyshell with the underfloor design of the Transperth B-series electric multiple unit.

Classified as the ‘4000 class‘, the first train entered service in February 2014.

Like the previous Adelaide order the Dandenong plant was involved in the contract, but this time they were responsible for completion of the entire train, which was then transported carriage-by-carriage by road for the thanks 700 kilometre section of standard gauge between the broad gauge rail networks of Adelaide and Melbourne.

An interior related footnote

As delivered the Comeng trains in Melbourne had 2-by-3 seating with tartan cushions on white fibreglass bases.

John Dunn photo

A design also applied to the Adelaide version.

In the 2000s the Melbourne trains were refurbished, with the seats replaced with a more spartan design with less padding.

An idea also copied by Adelaide.

But Victoria’s VLocity trains designed for country services received 2-by-2 high back seats with comfortable padding.

A seating layout that the Adelaide 4000 class trains also received, but with a more suburban style seat.

Sources

The book series “Comeng: A History of Commonwealth Engineering” by John Dunn covers the history of all four classes of train mention in this piece, across Volume 4 (1977-1985) and Volume 5 (1985-1990 plus ABB, Adtranz and Bombardier to 2012).

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Aluminium channel to be specific.

And others are made of timber.

Two separate pieces, tied together to form a truss.

So what gives?

The answer is above you

Look up – at the 1500 volt DC traction power used to power Melbourne suburban trains.

Level crossings on the suburban network use timber boom barriers, because if they get pushed into the overhead wires, the last thing you want is something metal forming a conductive path.

While V/Line and freight lines are free to use the simpler and cheaper metal boom barriers, as they don’t have the same electrical safety concerns.

Just the usual worries about vehicles driving through them.

Footnote: swapping metal for timber

In 2012 suburban trains were extended to Sunbury, by electrifying the existing railway.

As a result every level crossing between Watergardens and Sunbury had to have the metal boom barrier arms removed.

Google Street View 2009

And replaced with timber ones.

Google Street View 2018

And on language

In Victorian the official name for the arms that lower to prevent road vehicles from crossing the tracks is “boom barrier” – not “boom gates”.

The term boom barriers is synonymous with the term level crossing gates. It is used to denote flashing lights and half road boom barriers.

Crossing gates that swing across the tracks and are operated from a signal box are called “interlocked gates”.

While gates that need to be moved by hand are called “hand gates”.

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I’ve spotted them up in Queensland, where they use the 25 kV AC electrification system.

I’ve spotted them over in Adelaide, which also adopted the same voltage for their new electric trains.

And I’ve noticed them in Sydney, which uses the same 1500 volt DC system as Melbourne.

And curiously, on the Sydney Light Rail, which uses 750 volt DC power for traction.

The reason for these insulation gaps is safety – if the overhead lines that power trains fall to the ground, the last thing you want to happen is the entire railway station become live, and electrocute any passengers who happen to be touching a metal object! By providing insulated gaps in metal fences between the ‘trackside’ and ‘station’ sections, this risk is reduced.

Back in Melbourne, I’ve never seen an insulated gap in our station fences – only jumper cables between the overhead stanchions and the running rails.

And grounding connections between the tram fences and the tram tracks.

It makes me wonder – why doesn’t Melbourne have insulated gaps in the metal fences around out railway lines?

Some recent developments

About five years ago Melbourne started adding some new.

Insulating plastic shrouds around overhead stanchions on station platforms.

I wonder what the driver for their rollout was?

Further reading

The Transport for NSW Asset Standards Authority (ASA) has published Guideline on Earthing and Bonding at Railway Stations that explains the safety issues further.

At railway stations, three main types of risks may exist:

1. Risks associated with 1500V DC stray leakage or fault current.
2. Electric shock risk due to 1500V DC touch & step potential rise under fault condition
3. Electric shock risk due to high voltage/low voltage distribution systems’ touch & step potential rise under fault condition

There is a possibility that overhead wiring structures may rise to a potential above earth. The risk of persons receiving an electric shock when standing beside an overhead wiring structure and touching the structure is present and is of concern.

Other hazardous situations where persons could receive an electric shock is when physical contact is made by touching overhead wiring structures at the same time as they touch lighting poles, metallic parts of canopies or awnings, steel troughing, metal fences or rolling stock.

In order to minimise these risks, methods have been developed and deployed for the overhead wiring system.

As well as a document detailing the specifications for insulation panels found in their fences.

Insulation Panels

Insulation panels, a minimum of 2200mm in length, are required in metallic fencing in the electrified area to break the fence up into short electrically isolated sections. The panels consist of the fence material with supporting posts that are non-metallic. The panels are installed where ‘continuous’ fencing:

• would otherwise approach within 2.0 metres of an OHW structure (including any metallic attachments to the OHW structure such as switch handles, back anchor guy rods etc)
• would otherwise approach within 2.0 metres of station fences, foot bridges, rail bridges, entrance fences and metallic buildings
• runs parallel to, and within 2.0 metres of, above ground metallic signalling/cable troughing or air lines. The insulating panels must be located directly adjacent to the insulated joint in the signalling/cable troughing or air lines
• meets any high voltage substation fence (either RailCorp or local electricity distributor). Where the substation earth mat extends outside the substation fence, ‘continuous fencing must not enter the area of the earth mat.
• meets any pole mounted or pad mounted substation (either RailCorp or local electricity distributor). The ‘continuous’ fencing must not enter the area of the earth mat. The continuous fencing must also not be closer than 2.0 metres from exposed substation metal fittings.

Insulation panels are to be installed:

• to ensure that persons cannot contact ‘continuous’ fencing and any other metallic service such as OHW structures, station fences (associated with the station low voltage earthing system and water pipes) and footbridges that extend outside RailCorp property,
• at approximately 300 metre intervals in the ‘continuous’ fencing (with a maximum spacing of 800m in areas away from above ground signal troughing).

The non-metallic posts shall have a clearance of minimum 50 mm and maximum 100 mm from the adjacent metallic post of the ‘continuous’ fencing. Each non-metallic post must have a warning sign attached as shown on the drawing.

The bottom rail shall be installed so as to remain 80 mm clear of the ground.

Security and High Security Fences

When installing security and high security fencing, the fence shall be designed and positioned so to reduce or eliminate the requirement for insulation panels. Where insulation panels are required and can not be avoided, they shall be of a design that complements the high security performance of these fence types.

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