TO those familiar with urban rail, Melbourne is a city synonymous with trams. With 27 routes and a total length of 249km, Melbourne's network rivals other light rail giants such as Vienna in its scale, carrying around four million passengers per year.

But the city also relies on an extensive suburban rail system, and this too has witnessed sustained growth in recent years with a 70% increase in passenger numbers over the last decade. In 2011 10% of commuters travelled into the city by train, well above the Australian average of 6.3%. With most population growth expected to occur in the north, west and east of the city over the next 20 years, and most new employment in the city centre, weekday ridership is expected to more than double to 1.7 million by 2031 with an annual growth rate of about 4%.

This means more capacity is urgently needed on a network already under pressure. On March 27 Public Transport Victoria (PTV) unveiled Network Development Plan - Metropolitan Rail, a 30-year blueprint for the development of the suburban rail network, which if implemented in full could increase peak capacity by 50% by 2023 and 100% within 20 years.

The line-by-line proposals seek to accommodate rising demand while reconfiguring the timetable to improve connections with light rail and buses, and extending the network to areas not currently served by suburban rail.

The aim is to develop what PTV terms a "metro-style" system, which is defined by the following parameters:

• simple timetables with turn-up-and-go frequencies

• stand-alone end-to-end lines which do not intersect or merge with other routes, allowing disruption to be contained

• modern high-capacity signalling to maximise track capacity and enhance reliability

• high-capacity trains designed to minimise station dwell times, and

• grade-separated level crossings where the increased service would cause unacceptable traffic delays.

To achieve this, PTV prescribes investment in new infrastructure and rolling stock, alongside steps to optimise the performance of existing resources.

The plan is split into four stages, each roughly covering a five-year period. Stage 1 will be completed by 2016 and aims to tackle immediate critical constraints in the network, while providing a basis for expansion in future stages. Key projects include the already-committed Regional Rail Link (RRL) with new stations at Tarneit and Wyndham Vale and additional platforms at Southern Cross; seven new trains and associated power supply and stabling upgrades; and 40 extra V/Locity dmu cars, which are on order from Bombardier with deliveries due to start next year.

In addition, an order for 33 new high-capacity trains will be placed, and the 2011-12 Victoria state budget has allocated $A 210m towards the procurement of the new fleet. Initially these trains will carry up to 1100 passengers but will be designed to allow extension up to 220m in length. Emus in the current fleet are 143m long, and most platforms can accommodate 155m-long trains, although "challenging" infrastructure work would be required at city centre stations such as Flinders Street and Richmond to support the introduction of 220m-long trains. The report rules out double-deck trains as a viable solution to this problem because of the impact on dwell times and the need to increase station capacity to cope with different loading patterns.

The completion of the RRL in 2016 will allow timetables to be recast on all metropolitan and regional lines, enabling the introduction of a longer peak on some lines and improved off-peak and late night services. This will segregate regional services from suburban trains on the Sunshine and Werribee lines, providing an immediate and much-needed capacity boost on these routes.

The second stage will be the first step in turning the suburban network into a metro-style system within 10 years. Central to this will be the construction of the 9km Melbourne Metro tunnel, which alongside the provision of new trains and signalling is singled out as one of the core requirements for establishing high-frequency services. Running via the city centre, the tunnel will link South Kensington and South Yarra with five new inner-city stations. The tunnel will significantly increase capacity on the Werribee, Craigieburn, Sunbury, Upfield, Sandringham and Frankston lines, and will permit the operation of 19 additional peak-hour services.

Xtrapolis BelgraveOther enhancements in stage 2 include doubling the Melton line; upgrading the Dandenong line; and resignalling the Hurstbridge, Sandringham, and South Morang lines. The latter will be a pilot project for the implementation of high-capacity signalling, although the transport plan does not identify a preferred technology. The report notes that the existing system currently operates at around 15 trains per hour (tph) and could operate at 24tph in ideal operating conditions, but it suggests that investment in high-capacity signalling could support operation at "up to or beyond" 30tph.

The launch of the revised timetables following the completion of the RRL in 2016 will put considerable strain on the train fleet, requiring all 210 existing suburban trains to be available for service at peak times. In stage 2, the fleet will be expanded with the delivery of the first batch of 33 high-capacity trains and an order for a further 70 sets will also be placed. In addition to providing additional capacity, new trains will also be required to allow the retirement of older emus.

Additional measures in stage 2 will include adaption of the timetable for metro operations, with power supply upgrades and track and signalling alterations for high-frequency services.

The completion of the Melbourne Metro tunnel will allow all lines to be segregated from one another except in locations where trains need to access stabling or depot facilities. PTV says this will increase capacity and improve the reliability of the network, which is currently prone to delays spreading between lines. Furthermore, the report notes that segregation of the network will allow trains to be dedicated to particular lines, so trains can be configured to the specific operating conditions of the route.

Stage 3 would be completed within 15 years, extending the network to areas not currently served by suburban rail, taking advantage of the additional capacity built into the system by stages 1 and 2. Proposed projects include new lines to Melbourne Airport and Rowville; the diversion of South Morang services into a new tunnel between Clifton Hill and Southern Cross, allowing construction of a new line to Doncaster; Melton line electrification; and a further order for high-capacity trains, which would displace the remaining Comeng sets.

The rail link to Avalon Airport is not considered in the plan, although PTV notes that the Victorian government has given a commitment to secure the alignment for the line and is carrying out planning and design work with the aim of starting construction within five years.

The fourth stage would be completed within 20 years and includes reconfiguration of the City Loop to provide seven separate independently-operated lines through the city centre; four-tracking the Burnley - Camberwell line; electrification to Geelong and Wallan; and extension of the South Morang - Southern Cross line to Fishermans Bend.

While many of the early projects, including RRL and the Melbourne Metro tunnel are fully or partially-funded, the delivery of longer-term investments within PTV's proposed timetable will require further financial support from the state and federal governments. PTV says new funding models are currently being evaluated which could support the planned projects. In the meantime, PTV says detailed planning work will continue on projects outlined in the plan to allow work to begin as soon as possible.

The plan is unquestionably ambitious in its scope, but its commitment to optimising existing network capacity in the short-term, and its incremental approach to establishing metro-style operations, demonstrates that PTV has a clear vision of how the Melbourne region might support a sustained increase in rail passenger numbers over the next 20 years.

Photo: Chris Walters