Weather will not delay construction of modular bridge
The construction industry is long familiar with the impact that weather delays can have on a project’s completion – just a few days of rainy weather can wreak havoc on tight schedules.
To help limit on-site work and prevent weather affecting project schedules, the founders of Lifting Point came up with the idea of splitting the manufacturing and form work into a self-supporting structure, with the only site work required being basic preparation and filling with concrete.
So far the company has completed a prototype – the Toyoto Tsusho Bridge near Goulburn (pictured above), which was Australia’s first modular bridge. The bridge comprised two lanes at a 12 m span and is rated to take a fully loaded V-double truck based on the New South Wales RMS bridge requirements.
David Henderson, chief strategy officer at Lifting Point, said the on-site work took less than three days.
“The rest of the time was simply concrete curing or off-site work, and that was the real key advantage, the fact that we can get that bridge on-site and in the ground with no particular site prep required other than joining the bridge to the road and putting some abutments in,” Henderson said.
“The abutments themselves were pre-formed so that we could deliver them straight up the back of a truck and pour concrete. The main advantage there is there’s little or no risk of weather interruption.
“There’s also no dangerous handling of form work on-site, and because the form work itself is fully self-supporting, there is already a safe structure for people to work on that is laid down in the form of a pan.”
On-site work included drilling the piers, cutting away earthwork, dropping the abutments in and pouring the piers and the abutments with concrete in a single day.
“We dropped the bridge pans straight onto the bridge abutments, attached the side rails that are rigidly attached to the steel form work, and then just rolled in the concrete trucks and filled it with concrete and secreted that off and then allowed it to cure,” Henderson said.
Henderson said if the bridge was constructed using precast methods, it would have taken 18 to 20 days of on-site work to carry out the preparation for the lifting crane to drop the precast sections in, which can experience rain interruptions that can delay work.
“Whereas it was actually raining when we were installing the bridge, and it caused no difficulties at all because the equipment we were hauling was so light, we had no [problem with] vehicles getting bogged or needing to have pressure heads and supports for heavy cranes,” Henderson said.
“Our form work without the concrete for a single panel weighs less than 3 t, so it can be lifted with a very small crane, and precast concrete obviously weighs significantly more because it’s already got the concreting section.”
In the factory, Henderson said it took around five days of work, with fabrication carried out by hand without jigs or fixtures.
Now that the company has a prototype completed, it is working on shortening the manufacturing time in the factory through design iterations and improving the workflow.
“So the first prototype was really proof of concept and it worked very well, and during the installation we came up with lots of techniques to shorten the time,” Henderson said.
But challenges remain for the company, with civil engineering an industry that can be slow to accept change, according to Henderson.
This has meant the conservative nature of the profession can view newer technology with some hesitation. But Henderson said larger civil companies are seeing the opportunity to slot this technology into their current mix, particularly in areas where access is difficult or projects are at risk of weather bad weather.
Interest has also come from regional economic development, particularly in the Asia-Pacific, and work related to disaster relief.
Lifting Point is now chasing local government procurement work to allow it to underwrite growth into other markets around the world.
“We certainly believe that if we are successful in disrupting the civil engineering procurement methodology that’s currently in use, we should be able to build these bridges within the lead time of delivery,” Henderson said.
[Image: The Toyoto Tsusho Bridge near Goulburn.]
Infrastructure will be a major topic of discussion at the Australian Engineering Conference 2016 in Brisbane on November 23-25.