Machine Control and Site Positioning Systems support a completely ‘peg-less’ roadway construction site driving increased accuracy and an accelerated project schedule

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Seymour Whyte Construction was selected in a joint venture with another regional contractor to deliver extensive repair and rehabilitation works to Landsborough Highway in Queensland, Australia. The entire highway is an important part of the National Highway system linking Darwin and Brisbane. Seymour Whyte is an Australian-owned company that provides construction and engineering solutions to clients and as well as construction services to the transport, resources and utilities sectors across Australia.

Sponsored by the Transport Network Reconstruction Program, the $102 million construction and flood repair project is scheduled to take 18 months to complete―however the Seymour Whyte team won’t rest until they beat client expectations.

Seymour Whyte was contracted for road reconstruction, shoulder reconstruction and pavement patching across a two-lane stretch of road.  The 107 kilometer stretch between the towns of Barcaldine and Longreach consists of 68 kilometers of widening and full reconstruction and realignment of the road. The rest of that section involves repair and resealing work. Approximately 230 kilometers south, another 16 kilometer stretch of the Landsborough Highway is also being renewed. The second section between Augathella and Tambo includes road widening, full rehab of the current alignment, and 500 meters of shoulder replacement. In all, 38 floodways are being rehabilitated and 46 existing drainage lines will be extended or replaced.

Tom Williams, surveying manager for Seymour Whyte, points out that for this project his team is responsible for building at least 85 kilometers of temporary roads at these sites. Not only that, Landsborough Highway is a main artery for Queensland making it highly traveled by large semi-trailer trucks and road trains, local motorists, and tourists.

“One of the challenging elements of this project is that even the design and build of our temporary infrastructure needs to be precise because of the size of trucks we’re talking about,” said Williams. “The distances of these roadways also mean we would need truckloads of wooden pegs and survey crews to stake grade lines.”

A machine control technology advocate and experienced user, Williams selected Trimble Site Positioning Systems for off machine work and the Trimble GCS900 Grade Control System on a number of machines along side the Cat^® AccuGrade^™ Grade Control System on Cat machines for this project. The crew worked with subcontractors as well as the local Trimble dealer, SITECH^® Construction Systems, to set up the project and equipment with machine control capabilities. In total, 14 machine control systems were installed. The machine control systems included a mix of GPS/GNSS and total station-based systems. Across the project, 17 graders are being used; Williams explains that because the area is generally flat, little earthworks is required with a majority of the effort focused on precise trim work. The Total Station based survey system was chosen because it provides fast, accurate measurement.

Across the two project locations, SITECH Construction Systems set up 14 Trimble Total Stations, including nine Trimble Site Positioning Systems for graders, two Site Positioning Systems and three Trimble S6 DR for surveyors. The team uses radios for communications and GPS corrections to the four base stations. The Trimble Site Positioning Total Stations were used on the project for surveying. The base station equipment consists of a GNSS receiver, GNSS antenna, radio and radio antenna. These receivers enable remote configuration and they provide corrections to Trimble Site Positioning System GPS rovers. The grade control system accurately positions the blade in real time. This improves the operators’ productivity and profitability while minimizing material overages.

Seymour Whyte designers created digital terrain models for grading. Then the machine control system uses GPS technology to compare the blade position to the 3D site plan and signals the operator to raise or lower the blade automatically to achieve the design requirements. This process was used to perform initial earthworks and to build the 85 kilometers of temporary roads.

Williams is proud to report that the two Landsborough construction sites today run with four surveyors, instead of eight or even 10. Williams asserts that with Trimble and Cat machine control systems, his survey crew is much more productive. This is significant because in this remote area of Australia, professional surveyors are increasingly difficult to find. He explains that traditional staking or pegging is time intensive because it involves survey crews establishing horizontal and vertical controls and running preliminary lines across the project. More, it takes dozens of surveyors because grade stakes must be set and re-set to match the design and keep pace with changes. This requires the shuffling of surveyors from location to location and is a major productivity drain.

The Seymour Whyte team was also able to optimize their process by using fill material from the project site to build the temporary roads, instead of hauling it in from off site. He explains that any material they can keep from buying and hauling in, directly translates to return on investment and the project being more profitable. Overall, Williams believes he can do the job more accurately and in half the time with Trimble construction technology and Cat machine control.

“The Trimble and Cat machine control has completely eliminated the need for staking; it’s also raised productivity levels which brings a lower price tag to the overall project,” said Williams. “We are able to quickly build and rehabilitate these roads in five kilometer sections.”

Because of the long distances covered by the roadway, Williams had to get creative about using the base stations.

“We built custom trailers with solar panels and aerial masts for two of our Trimble base stations― they are completely self-contained units,” said Williams. “That way we can quickly move them from one spot to another. We also have one base station we set up for the day and the last one is permanent.”  

Several months and dozens of kilometers into the Landsborough Highway project, Williams is happy with the results of using Trimble and Cat machine control systems as well as Trimble Site Positioning Systems. In fact, the project is currently ahead of the original 18-month schedule. Williams attributes the increased productivity to his crew and their skilled use of machine guidance.

“I believe that the job would take twice as long without machine control,” said Williams. “We can get through so much more work and it’s done to a better standard because we have accurate level control everywhere along the job, not just where we had pegs in the ground.”