The centerpiece of the budget is construction of Melbourne's new Metro Tunnel with an allocation of $A 2.9bn over the next four years and the balance for the $A 10.9bn project fully committed in its forward estimates. The state government has decided to fund the project in full as it believes federal assistance is now unlikely.

The Metro Tunnel will be built and operational by 2026 and the project will allow more trains to run in and out of the city by giving the Cranbourne, Pakenham and Sunbury lines their own route through the city centre.

Commuters in Melbourne's outer north will be connected to train services for the first time with $A 587.7m allocated to fund the Mernda suburban rail extension. The project includes 8km of track-doubling between South Morang and Mernda and additional train stabling facilities.

The Mernda extension is being delivered by the Level Crossing Removal Authority and is due for completion in 2019. Expressions of interest for design and construction contracts were invited in February this year and construction will start next year.

A single-track bottleneck on the suburban Hurstbridge line will be doubled to enable faster, more frequent and more reliable services for north east Melbourne.

The $A 140.2m project will see a new tunnel constructed alongside the existing tunnel for the doubling of 1.2km of track between Heidelberg and Rosanna. Power and signalling will also be upgraded and the two level crossings eliminated at Alphington and Rosanna. Construction will start before the end of the year and the project will be finished by 2019.

In addition to infrastructure, the budget includes a boost for Melbourne's rolling stock fleet with $A 875m allocated for the previously-announced order for 28 additional high-capacity suburban trains.

Regional projects

Beyond Melbourne, a total of $A 1.3bn will be invested in regional public transport with upgraded infrastructure, 170 additional services, and more funding for V/Line maintenance and operations.

A A$ 518m project for the Melbourne - Ballarat line will see track-doubling between Deer Park and Melton, additional passing loops, extra platforms at key stations, and extra car parking as part of a comprehensive upgrade to provide more frequent services to Ballarat and accommodate population growth around Melton.

V/Line will receive funding for 27 extra Bombardier VLocity DMU vehicles in addition to the 21 cars ordered last year to reduce overcrowding and increase frequencies on regional lines. In addition, $A 15m has been set aside for upgrading locomotive-hauled coaches on the Melbourne - Albury line.

V/Line will be bolstered with $A 198m for improved maintenance on the regional network in light of problems experienced earlier this year with severe wheel wear on the Vlocity fleet.

The government will also fund studies into major upgrades for the Gippsland and Bendigo lines, a new line to Armstrong Creek near Geelong, and track-doubling between South Geelong and Waurn Ponds.

The budget also provides funding to investigate and plan for the next generation of regional rolling stock.