This month sees the launch of the first tunnel boring machine for the orbital Chatswood - Epping - Parramatta rail link connecting the northern and western suburbs of Sydney

John Barraclough

Project Director, Parramatta Rail Link

COMPLETING a missing link in the metropolitan rail network between western and northern Sydney has been a commitment of the New South Wales government for the last six years. The Parramatta Rail Link forms the centrepiece of the state's Action for Transport 2010 agenda, an ambitious plan to improve the integration of transport services in this rapidly-expanding city. As well as the new rail link, the plan includes major road projects, and express bus services in western Sydney.

Unveiled by former state Transport Minister Carl Scully in July 1998 (RG 8.98 p503), the Parramatta Rail Link is intended to expand the long-term capacity of the CityRail network. Increasing congestion on the Main West line between Strathfield and central Sydney is preventing CityRail from introducing extra services from the growing residential suburbs in the north and west of the conurbation.

By providing an alternate route into central Sydney, via Epping in the north rather than Strathfield in the Inner West, the Parramatta Rail Link will create capacity for up to 18000 additional passengers from the outer parts of the Main West line during the 3h 30min morning peak. In addition, the line is conservatively estimated to attract around 20000 new riders each day at the seven stations along the route. This is equivalent to an additional 11·6 million passenger trips a year.

The link will bring rail services to suburbs around Macquarie Park for the first time, and provide direct links between key regional centres such as Parramatta, North Ryde and northern Sydney. By increasing the overall use of public transport, it will help to improve air quality through a reduced reliance on car travel. The CityRail network will gain three new underground stations and one on the surface. Seven existing stations will be upgraded, and the interchanges at Parramatta and Chatswood significantly enhanced.

The official promoters are the State Rail Authority, which runs CityRail services, and Rail Infrastructure Corp, which owns and maintains the state's rail network. The railway is being built and fitted out by the Parramatta Rail Link Company on behalf of its shareholders, SRA, RIC and the Director General of Transport NSW. When complete it will be owned by the NSW state government and operated by CityRail.

The 28 km route is being built progressively. Construction is initially concentrating on the eastern section between Chatswood and Epping, which is now expected to open in mid-2008. The second section from Epping to Parramatta is scheduled for completion at the end of 2010. This will incorporate part of an existing branch between Carlingford and Camellia, where the line will come to the surface to run on the existing alignment. The first phase is the largest tunnelling project currently underway in New South Wales.

Planning process

The environmental impact statement for the project was released in December 1999, resulting in a lengthy process of environmental impact assessment and community consultation, which attracted more than 4000 submissions. Planning approval was finally received in February 2002.

In granting consent, the Minister for Planning placed 269 conditions on the project to minimise the impact of both construction and operations. These concern noise and vibration mitigation, construction methodology, working hours, environmental management and community consultation, as well as the project's relationship with other government projects and the urban domain. Detailed plans of management have been required from each contractor, to show compliance with these conditions as well as their contractual obligations.

The most contentious issue during the assessment process was the decision whether to build a high-level rail bridge through a popular picnic area in the Lane Cove National Park. From a railway point of view a bridge was preferred, as it would avoid steep gradients on the 4 km line between the National Park and the North Shore line at Chatswood.

However, over 85% of the submissions received objected to a bridge, and it was decided to build a cut-and-cover tunnel under the Lane Cove river. This in turn required a maximum gradient of 3% for the new route to climb back up to the level of the North Shore line. The cut-and-cover tunnel was considered the best environmental option.

The bridge decision also impacted on the route through the Lindfield and Roseville suburbs to the west of Lane Cove, which had to be realigned to maintain the ruling gradient. This in turn meant that a group of residents who had previously thought they were unaffected now found their houses lay within the approved 60m wide corridor in which the two rail tunnels would be constructed.

Other issues raised by the community during the planning process primarily concerned noise and vibration, the impact of construction work and the effect on property values. The change in alignment exacerbated this concern among property owners.

Contracts awarded

As finally approved, more than 70% of the 28 km double-track route will be located in parallel single-track bores 7·2m in diameter. These tunnels will lie between 16m and 65m below the surface, and will be reinforced by rock anchors and other structures. The route will pass beneath around 1000 commercial and residential properties. However, no residential properties on the surface will have to be demolished, which is a remarkable achievement in a populous suburban area.

The tunnels will use a combination of boring and cut-and-cover construction, road header excavations and some controlled blasting, with open cuttings for the ramps to and from the surface. In geological terms, the alignment lies predominantly in a belt of Hawkesbury sandstone.

In July 2002 the Thiess/Hochtief joint venture was awarded a contract to build the Epping - Chatswood section, including construction of the tunnels and excavation of the station caverns, tracklaying, and the installation of signalling and communications systems. This is the largest single publicly-funded contract ever awarded by a NSW government.

In addition to this contract, RIC has been commissioned to undertake enabling works to integrate the Parramatta Rail Link with the Main North line at Epping and the North Shore line at Chatswood. John Holland Pty Ltd (formerly Transfield) was awarded a contract for civil works on the existing route through Chatswood, including the rebuilding of several key rail and road bridges.

Other contractors include Maunsell, as technical adviser to the project, and Bovis Lend Lease as contract manager for the Chatswood - Epping works and the NSW government architect. Local architectural group Hassell will develop the Parramatta Transport Interchange and intermediate stations between Epping and Delhi Road, whilst Daryl Jackson Dyke Architects will undertake the concept design for Chatswood Transport Interchange.

Construction starts

Substantial construction began on November 25 last year, when excavation of the first access ramp began at the principal worksite near DelhiRoad. This month will see the first of two tunnel boring machines launched from here, to dig 13 km of tunnel commencing west to Epping. The second bore will also be started within a month or two.

Supplied by Robbins Asia Pacific, the TBMs were assembled and tested in the Hunter region of New South Wales earlier this year. The bulk of the spoil will be removed through the main worksite which has easy access, being bounded by the M2 motorway, Wicks Road and Epping Road.

A number of other sites have already been established along the route, primarily in the Macquarie Park and North Ryde areas. A worksite has been established within the Lane Cove National Park, from which the construction of the cut-and-cover tunnel began in April. This section will require the temporary installation of coffer dams within the Lane Cove river to maintain water flow at all times, and provide a safe environment for the workers.

The section of tunnel between Lane Cove and Chatswood will be excavated by the same TBMs working their way towards Epping, which will travel through the cut-and-cover tunnel once it is completed.

Safety in design and construction is among the highest of priorities for the project team and its contractors, with regular safety audits a key part of management procedures. The project team has placed considerable emphasis on maintaining open relationships with its stakeholders and the community to ensure the project is delivered in a responsible and environmentally-sustainable manner. PRLC is also committed to delivering this important public transport initiative within the allocated timescale and budget.

  • CAPTION: Former NSW Transport Minister Carl Scully, and Executive General Manager for Thiess Pty Ltd (NSWand ACT) David Saxelby at the start of works in November 2002
  • CAPTION: Top: Roadheaders are being used to excavate the drives providing access to the running tunnels and underground stations
  • CAPTION:The new line is intended to relieve the Inner West rail corridor and connect suburban centres north and west of Sydney
  • CAPTION: Clearance work underway at the main construction worksite near the M2 motorway at DelhiRoad
  • CAPTION: Artist's impression of the underground platforms at Macquarie Park station