Complete line for box culverts for the Western Harbour Tunnel project in Sydney, Australia

Moldtech has recently commissioned a complete production line for box culverts for the ambitious Western Harbour Tunnel project promoted by the New South Wales Government in Sydney.

The client, Acciona Australia, is a subsidiary of Acciona, one of the largest European engineering firms, a renowned multinational company focused on sustainable solutions and infrastructure that has been awarded large key infrastructure contracts in Australia in recent years.

The project involves a new 6.5km tolled motorway tunnel beneath the harbour, intended to reduce pressure on some of the city‘s main roads and improve mobility, avoiding Sydney´s CBD and relieving traffic on the Sydney Harbour Bridge, the Sydney Harbour Tunnel, and the Anzac Bridge. Acciona´s package includes the construction of approximately 4.5km of tunnels from Birchgrove, under Sydney Harbour and on to North Sydney, with a 1.5km underwater section.

The approved construction solution using two tunnel boring machines, precast tunnel lining segments and precast box culverts, offered great advantages as compared to the previous harbour tunnel project completed more than 30 years before, avoiding dredging of the seabed under the harbour with a significantly reduced impact on the environment and minimizing disruption to recreational and commercial port users, while protecting marine biodiversity.

The use of precast tunnel segments and culverts allowed for a significant saving in the use of concrete and steel compared to initial plans, while improving efficiency and reducing construction times.

High-performance equipment

Moldtech has designed a production line according to the client´s requirements and layout with two specially designed MT20 drycast machines with 12 bases to produce the targeted number of box culverts per day. This MT20 system is a high-performance equipment for manufacturing vibropressed drycast box culverts with great productivity and flexibility as it is normally designed as a modular machine to cast box culverts of different sections. The system is comprised of an interior mould, an exterior mould, a set of bases, a top press, a vibration system with high frequency vibrators and a converter, with and a complete hydraulic system to operate all pressing and fastening movements.

This equipment does not require civil works/pit for its installation and could be transported and installed to produce near construction sites to save transport costs and easily relocated once the project is finished. In this case, the machines have been specially designed with a curved side to match the bottom of the tunnel on which the culverts will be installed to build a 3.2x2.1m utility corridor under the six lane motorway. Special provisions have also been made on the mould, to assemble different types of fixing elements inside the culverts for communications and other installations.

Besides these machines, Moldtech has also supplied a set of ancillary equipment and accessories to improve efficiency and safety:

A hydraulic turning machine with 30T that safely and efficiently turns the culverts 90º into their final installation position.

An automatic lifting clamp with 30T capacity, allows lifting the box culverts casted vertically, to safely transport the units to the 90º turning machine without requiring lifting anchors and voiding rigging works.

Two tilting/laydown concrete buckets with 3m³ capacity facilitate casting, loading directly from the mixer truck and efficiently pouring at the top of the machines with through a side screw conveyor.

Additional accessories such as support guides for positioning the machines, access stairs in each machine position to the working platforms, or an elevated platform as a machine cleaning and oiling station, have been supplied to facilitate works at all stages of the process.

Up to 1,400 culverts for the tunnel

All this equipment has been designed in close collaboration with Acciona and according to their proposed layout of the facility, planned with the required walkways and fenced areas as per a stablished work process to maximize efficiency and safety as per Australian strict WHS standards. After satisfactory initial production tests and training of local workers, the client is starting to produce at a great pace to meet the demanding project lead times, having to build up to 1,400 culverts for the tunnel.

This cooperation with Acciona strengthens Moldtech´s position as an international supplier of efficient technological solutions for the increasing demand of precast concrete elements for large infrastructure projects. Once built, this complex engineering project will become a landmark, easing congestion on existing roads, and once again, showing Acciona´s capabilities as an efficient provider of challenging sustainable infrastructure.