Main Roads Western Australia is upgrading its rural road bridges, many of which are ageing. Minyulo Brook Bridge is on the Brand Highway between Perth and Geraldton, and since March 2018 it has undergone a significant strengthening and remediation project.
The existing bridge at Minyulo Brook was showing signs of fatigue, requiring a strengthening of the substructure and superstructure. It needed new stringers (secondary beams), replacement of half-caps (bearings on bridge piles), installation of steel driven piles and demolition of the existing overlay. It also required construction of a widened concrete deck and approach slabs for the bridge, as well as a new guardrail.
However, while the bridge was being upgraded, one lane was kept open so traffic could flow between Perth and Geraldton. This meant the entire structure had to be strengthened for the loads from truck and car traffic while the existing foundations were replaced.
The principal contractor at Minyulo Brook was the bridge engineering specialist, Fortec Australia. The firm carried out the works from March 2018 to July 2019, with a team of eight people.
To stabilise the bridge and keep it open, Fortec needed the structure to be propped, which it did with a fleet of 64 mechanical props, steel plates and 320 sleepers on the creek bed as foundations for the props.
The mechanical props and sleepers were provided by Coates Hire, which also supplied site accommodation for the principal and head contractor, supply and installation of 500 metres of BG 800 traffic barriers with end terminals, and 16 steel plates to the location.
Fortec Australia Site Manager at Minyulo Brook, Andrew Withers, says the remote site needed quality equipment as well as a service assurance, given its remoteness.
“Our project is in a remote location, 186km from Perth,” says Withers. “There is no local industry that could assist with any of the equipment or machines required to service our project.”
He says the main equipment used in the remediation project was the propping and sleepers, which had to safely hold up the bridge during the works. The Coates Hire propping system also created enough room for the contractors to work efficiently on the bridge, and Coates Hire’s props were faster to install and dismantle than other systems on offer.
“Without the use of the propping system supplied by Coates Hire, we would have had to resort to a more cumbersome and heavy propping system,” says Withers. “The alternative propping system would have had an impact on the project time-line.”
Not only did the bridge owner want at least one lane on the bridge kept open for heavy trucking, there were also limitations on the impact that the works could cause to the river bed.
“The Coates Hire propping system solved the restrictions imposed by the client and ensured the structure was adequately propped for vehicular traffic during construction activities,” says Withers.
Coates Hire Engineer – Temporary Works, Douglas Norton, says the project was typical of Coates Hire’s ability to support civil works outside the main towns and cities.
“In Western Australia there’s not a lot between the towns,” says Norton. “The customer doesn’t just want the equipment, they want it delivered and then serviced for the life of the project.”
He says Main Roads WA stipulated that the upgraded bridge be kept open while it was rebuilt, meaning it required safe and properly-engineered propping.
“The Brand Highway has a lot of heavy truck traffic on it, and our props have to withstand those loads,” says Norton. “We have a large fleet of System 15 props which are well suited to these projects.”
Norton says Coates Hire provided engineering consultation for the bridge-propping. Servicing and transport was provided for the bridge propping as well as for the accommodations and telehandler.
Andrew Withers says when doing civil works in remote locations the transport and maintenance services are as important as the hire equipment.
“Consultation with the Coates Hire temporary works engineer helped us find the system that would best solve our issues,” says Withers. “And the Coates Hire transportation offering was also important because we didn’t have the resources or time to provide our own transport to the site.”