The two towers for Sydney Metro’s iconic cable-stayed railway bridge over Windsor Road at Rouse Hill were erected recently.
The 270-metre bridge – the first of its type in Australia – is at the end of the four-kilometre skytrain. The bridge, being delivered for Transport for NSW by Salini Impregilo, was a design solution to community feedback which means any future upgrade of the Windsor Road and Schofields Road intersection will not be impacted by the new metro railway.
The steel towers that anchor the cable-stayed bridge were fabricated in the Glendenning factory of S&L Steel, and transported 17km to site at night, under police and pilot escort, on an 18-axle platform trailer.
They each weigh 210 tonnes and are 29m tall, with anchor points for eight cable stays on each of the sides facing the deck.
On the 4km skytrain, two large gantries erected the 1128 precast concrete segments that make up the deck.
This skytrain deck is 11m wide and an average of 9m in the air, with the segments weighing between 56t and 147t. The gantries lifted and positioned each segment, and held it in position while it was tensioned with steel cable. Each gantry weighed 600t and was 150m long.
There are 80,000t of concrete in the skytrain deck, which is tensioned by 1400km of steel cable.
Lift details
Cranes for the erection of the towers were supplied by S&L Steel, who subcontracted Gillespie Crane Services (Gillespies) for the erection of the steel towers. Gillespies used its own 350t capacity Liebherr LR1350-1 crawler crane fitted with a derrick ballast system with floating ballast tray; and cross-hired a 250t Manitowoc M999 crawler crane from Lampson Australia to act as a tailing crane. Smaller cranes supported the main lift cranes.
The Liebherr was rigged with 54m of main boom, 19 falls of rope on the main winch, 36.3t of central ballast, 99.6t of counterweight and 125t of suspended counterweight. Its 300t capacity hook block weighed 5.5t, and rigging added a further 2.3t. The derrick ballast tray was set at 13m radius for the main lift.
The Manitowoc was rigged with 27.4m of main boom, 11 falls of rope on the main winch, 36.3t of central ballast and 99.6t of counterweight. Its 147t capacity hook block weighed 3.1t and rigging added a further 2.6t.
For the first lift, the cranes were set up on hard stand beside the deck of the bridge, and the cranes picked up the tower in a horizontal orientation directly from the platform trailer. The Liebherr lifted at 14m radius and the Manitowoc lifted at 8m radius. The trailer was removed from the work area once the tower was supported by the cranes.
Removable fabrications at the top and base of the tower provided lifting points designed to ensure that the load did not clash with the rigging during the lift, and to separate the planes of the rigging for the top and bottom of the tower as it was turned from horizontal to vertical.
The Liebherr hoisted its end of the tower as the Manitowoc walked towards it, with the tower slowly rotating from horizontal to vertical, at which time the Liebherr supported the full load and the Manitowoc’s rigging was detached from the tower.
The Liebherr then raised the tower until it was above deck level, after which it slewed it over the deck and lowered it onto the securing bolts.
Once the nuts were tensioned on the bolts, the rigging was detached.
There was three millimetres tolerance over the bolts, and the tower could be moved locally to position it over the bolts.
The lift of the second tower was essentially a mirror image of the first, undertaken on the opposite side of Windsor Road.
Civil earthworks were progressively undertaken over several months prior to the lift programme, with specific emphasis on crawler crane operational areas to achieve ground compaction, specific ground levels and cross falls within operating parameters of both crawler cranes.
Timeframe and logistics
The first tower was lifted on May 21, 2017, and the second was lifted five days later.
Three days were taken to mobilise the cranes to site, three days were taken to relocate them to the opposite side of Windsor Road for the second lift, and a further three days were taken to demobilise afterwards. There were 134 transport movements required in total.
Panalpina World Transport Pty Ltd/ALE Heavy Lift was responsible for heavy haulage.
Closures of the full northbound carriageway and southbound fast lane on Windsor Road were required for the erection of the first tower, while the full southbound carriageway and northbound fast lane were closed for the erection of the second tower.
To minimise the impact on traffic, the road closures were only enacted once the steel tower had been rotated to the vertical position and was lifted from ground level onto the deck of the cable stay bridge to be positioned over the hold down bolts.
Acknowledgement: A Sydney Metro spokesperson provided extensive details for this story.
This article was originally published in the July issue of Cranes and Lifting.