Waking up in Geelong

You might have noticed something about Melbourne’s railway station footbridges – they are bloody high, with long ramps and stairs leading up to them. So why do they need to be so high above the tracks?

In the beginning

Melbourne’s first trains were short and steam powered, so there bridges didn’t need to be high above the track.

PROV image VPRS 12800/P1, item H 1123

But the introduction of electric trains from 1919 saw a need for increased clearances, to accommodate the overhead wires.

PROV image VPRS 12800/P4, item RS 0391

The 1953 Victorian Railways General Appendix gave the contact wire height as follows:

• Average height above rail: 16 feet – 16 feet 6 inches (4.48 m – 5.03 m)
• Minimum height under bridges (suburban area): 14 feet 6 inches (4.42 m)
• Minimum height under bridges (country area): 15 feet (4.57 m)
• Minimum height over sidings: 17 feet (5.18 m)
• Minimum height over level crossings: 18 feet (5.49 m)
• Maximum height: 19 feet (5.79 m)

Many footbridges already crossed the tracks prior to electrification, such this one in Moonee Ponds – constructed in 1890.

Ripponlea station – opened in 1912.

And Footscray station – rebuilt in 1901.

But these tight clearances remained for projects completed post electrification, such as Hawksburn station – rebuilt in 1914.

Camberwell – rebuilt in 1919.

And Middle Footscray – grade separated in 1928.

And later years

By the 1970s the clearance between trains and overhead bridges started to grow, with Yarraman station being one example – opened in 1976.

But it appears that exceptions were still permitted, such as West Footscray – rebuilt in the same year, 1976.

Enter double deck trains

In 1992 Melbourne introduced a trial double deck train – the 4D.

Weston Langford photo

As you might expect, a whole lot of infrastructure changes were required to accommodate a taller train – including the Swanston Street bridge at Flinders Street Station, and numerous overhead bridges along the Belgrave and Lilydale lines. The exception was the City Loop tunnels – designed with double-deck trains in mind, no modifications were necessary.

But still the 4D train was shorter than the double deck trains of Sydney – 4270 mm tall, compared to the 4380 mm tall Sydney Tangara train it was based upon.

It also also interesting to compare the height of the double 4D train, to Melbourne’s single deck train fleet:

WTT Network Configuration-Metro Rolling Stock (L1-CHE-MAN-016)

• Hitachi: 3759 mm
• Comeng: 3835 mm
• Siemens: 4141 mm
• X’Trapolis: 4214 mm

Turns out bolting air conditioning units to the roof of a train really eats up that vertical clearance!

Current standards

Metro Trains Melbourne standard L1-CHE-STD-011 “Overhead Line Electrification” gives the overhead wire heights as follows:

• Open route (nominal at support): 5.20 m
• Open route – slab track (absolute minimum): 4.46 m
• Open route – ballast & sleepers (absolute minimum): 4.61 m
• Open route (absolute maximum, excluding lead up to level crossings) 5.85 m
• Station platforms (nominal)5.20 m
• Station platforms (minimum): 4.94 m
• Level crossings (minimum): 5.64 m
• Level crossings (maximum): 6.10 m
• Pedestrian crossings (minimum): 5.00 m

Compared with the overhead wiring standards from 1953, only an extra 190 mm clearance is required under bridges – that’s less than one step! So why are such massive bridges being built?

Turns out standard L1-CHE-STD-025 “Transit Space Clearances” has the answer:

Section 9.2 shall apply to any new, or alterations to existing Infrastructure constructed or installed by MTM, or on behalf of MTM or PTV.

The minimum Vertical Clearance shall be 5.75m for new bridges or structures above the track. The Vertical Clearance may be reduced subject to the approval of the Chief Engineer, or delegate, following adequate demonstration of requirements in Appendix A – Reduced Vertical Clearance to Structures Requirements.

This explains the massive footbridges built in the past decades at rebuilt railway stations – such as Watergardens.

And Westall.

As well as the depth of rail underpasses such as Nunawading.

Gardiner.

And St Albans.

But why are some stations even taller?

If the climb out of the above stations seems bad enough, there are stations such as Sunshine where the ascent is even more formidable.

Metro Trains standard L1-CHE-STD-025 “Transit Space Clearances” alludes to the reason:

On tracks operated or maintained by Accredited Rail Transport Operators (ARTOs) or Rail Infrastructure Managers (RIMs) other than MTM, consideration shall be given to their minimum vertical clearances, particularly on Double Stacked freight corridors.

A double stacked freight train is far taller than any Melbourne train.

With the only Australian examples running through the ‘outback’ – between Adelaide, Perth, Darwin and Parkes.

But the capability to run double stack freight trains in Victoria is on the roadmap for the Australian Rail Track Corporation, operator of the interstate freight network in Victoria.

Tottenham to Albury (T2A) is one of 13 projects that complete Inland Rail. This section of Inland Rail is planned along 305km of existing rail corridor from metropolitan Melbourne to the Victoria-NSW border at Albury-Wodonga. This project will see enhancements of existing structures to provide increased clearances along the rail corridor. The enhancement works are required to accommodate double stack freight trains of 1,800 metres in length to be run on the track.

With their clearance requirements detailed in Section 7 “Clearances” of their Code of Practice:

New Structures on the Defined Interstate Rail Network (DIRN) and the Inland Railway Route

Unless otherwise formally approved by appropriate ARTC Executive General Manager, all new structures over mainlines and passing loops/sidings shall be constructed to give full plate “F” – i.e. this will give 7.1m clearance above rail.

In Melbourne the Defined Interstate Rail Network runs west and north-east from the Port of Melbourne, paralleling the following suburban tracks.

• Sunbury line, Footcray to Albion
• Werribee line, Newport to Werribee
• Craigieburn line, Jacana to Craigieburn

Which explains the massive footbridges found at West Footscray.

Laverton.

And Coolaroo.

As well as the Sunshine example from earlier.

Footnote – how long are the ramps?

I found this in a report by Opus Consulting regarding development concepts for Donnybrook station:

There is a preference for the provision of a footbridge for access across the tracks for the following reasons:
» The nature of the basalt ground conditions, along with anecdotal information regarding ground water and inundation conditions, suggests the use of a footbridge rather than a subway.
» Construction interfaces with the live train running lines make it more favourable to build a footbridge
» Footbridges are also preferred over subways because they provide a more favourable security environment
» It is expected that a footbridge will be more cost effective to provide

And the kicker:

Clearance requirements over the standard gauge interstate track is 7.1m which dictates:
» 128.8m of ramp length to ground level
» 15.9m of stair length to ground level

Clearance requirements over the broad gauge regional tracks is 5.75m which dictates:
» 97.2m of ramp length to ground level
» 13.2m of stair length to ground level

That 1.35 m of extra vertical clearance really makes a difference to the length of a DDA compliant ramp!