Translating ideas – Sydney Gateway

Multiplan has been playing its part in this high-profile, high-capacity roadway project praised for its impressive calibre of bridge architecture.

Linking Sydney’s motorway network with the city’s domestic and international terminals and beyond, the multi-layered design taps into the strength and design adaptability of our favourite construction material – steel.

Boasting three major bridges, 16 minor bridges including a pedestrian bridge and 16-span, 545m-long viaduct flyover, the design creates a complex network of roads traversing each other at different levels.

As a new entry statement for Sydney, the project will not only ensure easy and continuous travel, but the standout structures will also be highly visible elements appreciated from various locations and distances.

Modelling the vision

Well versed in multi-faceted bridgework projects, Multiplan was engaged to bring its decades of bridge modelling and shop detailing expertise to the project.

Working in a Direct Fabricator Engagement (DFE™) capacity, our team collaborated with client, engineers, surveyors, steel fabricator and transport contractor to ensure the smooth and seamless fabrication and erection of key aspects of this landmark design.

The first element Multiplan was engaged to work on was Bridge SB31, an 82m-long structure spanning the Alexandra Canal, on Airport Drive to Qantas Drive. The design consists of three taper box girders supporting the concrete deck.

The second project involved Span 6 and Span 11 of the high-level viaduct over Qantas Drive. Each of these two spans consists of five curved trough girders straddling approximately 55m to support the banked concrete roadway.

Complex curves made to look easy

“The viaduct spans are horizontally curved and supported only on their end piers, which restrain them from rotating,” says Multiplan Managing Director Kane Nitschke.

“Their extremely complex set of dimensional parameters create the curved and banked elevated roadway, and include curved and sloping trough girders with combination radii, tilted varying cross fall, along with additional precambers and cross falls.”

Using our one-of-a-kind DFE™ approach, the Multiplan team was able to bring an exceptional level of innovation and collaboration to the construction modelling and shop detailing processes.

“Our development of re-usable fabrication jigs and perfection of modelling techniques are prime examples of how our early and direct engagement can ensure fabrication efficiency and success,” Kane says.

“The innovations are also testament to the experience and diligence of our talented team.

“Our construction modellers and detailers take great pride in providing a holistic range of services to assist our clients with accurate documentation through every phase of procurement, fabrication, transport and erection of complex projects.”

Direct fabricator engagement the key

Multiplan developed precision models and fabrication drawings for the varying bridge trough girders, reflecting the precambers, curves and crossfalls of the finished roadway.

“Re-usable jig frames were developed for the girders to ensure accurate and efficient fabrication and distortion control,” Kane says.

Survey data schedules achieved client verification of girder dimensions in the jigs, while accurate material take-offs enabled advance ordering of high-grade steel materials, navigating long lead times.

The scope of work included fabrication models, detail drawings and data for girders, as well as providing set-out data, and liaising with surveyors for dimensional control of the girders and data for client verification survey.

Invaluable input was provided into transport arrangements for the steel girders, including bolster steelwork, through liaison with client, engineers and transport contractors.

When the girders arrived on site, Multiplan’s steelwork set-out and details allowed accurate splice welding of girder spans prior to erection lifts.

“The Sydney Gateway project demonstrates the insights and technical capabilities Multiplan can bring to each step of the fabrication process and the added value we’re able to deliver in a direct fabricator engagement capacity,” Kane says.

Multiplan is proud to work with Civmec on the Sydney Gateway project, along with Toro Engineering Services for the design certification of jigs and transport design.

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