As space in the centre of Melbourne gets used up construction over rail is becoming more commonplace, as this project, a first for Grimshaw, demonstrates
699 Bourke Street is the first commercial building to be designed by Grimshaw in Melbourne. Situated above the rail environment of Southern Cross Station, the building is the new Victorian office of AGL Energy Limited (AGL) and offers an exceptional workplace environment to its 1,500 employees.
Grimshaw worked closely with the developers of the building, Mirvac, and major tenants, AGL, to deliver an A-Grade office space that is designed to take best advantage of the unique over-rail air-rights site.
Construction over rail is becoming more common as Melbourne densifies, presenting tough design and technical challenges. In a typical building construction, basements and footings allow for flexibility in the location of structure and a place to hide bulky plant equipment and services. When building in the air, a new ground plane needs to be constructed and this was done for 699 Bourke Street, with 2m-deep concrete-filled beams that span 20m between supports. Aligned with the western edge of the existing Southern Cross Station roof, this ground plane sits 24m above the train tracks and is the lowest occupied level of 699 Bourke Street. All of the basic services, such as electricity and water, need to rise to this level to enter the plant equipment rooms.
A benefit of overcoming the technical issues is foremost the improved views and daylight; 90% of the office floor is within 12m of the high-performance glazed façade, surpassing a key requirement of the 6 Star Green Star office ratings. Excellent views can be obtained at all levels, with views of the undulating Southern Cross Station roof and Melbourne’s Central Business District (CBD) to the east, Mount Macedon to the north and Port Philip Bay to the south.
Conceived as part of the Southern Cross Station Master Plan designed by Grimshaw in association with Jackson Architecture, 699 Bourke Street forms a considered backdrop to the roof of the station while providing a strategic connection between Melbourne’s CBD and the Docklands precinct.
Grimshaw Partner, Neil Stonell, said of the air-rights development, “Rising 64m above the rail environment, 699 Bourke Street offers an important opportunity to bring the built urban form of Docklands closer to Melbourne’s city centre. In doing so, our design seeks to help unify the two precincts, delivering a building that not only responds to its urban context, but also delivers premium office space in a newly created Melbourne address.”
A key feature of 699 Bourke Street is the design of the building’s north façade which prevents glare reflectivity on to the rail yard environment below, mitigating risk to train drivers. To achieve this, Grimshaw led a detailed solar analysis to determine the solar angles and devised an integrated fixed-louvre screen which maintains views while preventing reflections. These louvres are an identifying feature of the north façade, a precise and layered surface which diffuses light.
The main address of the building is the Bourke Street Bridge which provides pedestrian access between the CBD and Docklands. To help identify the entrance and negotiate the 8m rise to the lowest lobby level of 699, Grimshaw designed a glazed pavilion that accommodates stairs and escalators, and which is delicately supported at only two points over the rail below. The foyer leads to the AGL lobby and Business Lounge and is designed to embrace its position in the sky by utilising light-weight, reflective materials such as glass and stainless steel.
From the lobby, an open-air public walkway provides a pedestrian laneway that connects Bourke Street Bridge and Collins Street at number 664.
699 Bourke Street was officially opened in 2015 by the Minister for Energy, Hon Lily D’Ambrosio.