Simon Chamberlain, General Manager, and Jason Carroll, Business Development Manager for Aptella’s new Paving Services division, spoke to Roads & Infrastructure about the team’s specialist skills and ability to work collaboratively with clients to provide optimised paving outcomes through a proven methodology.
With more than 15 years’ experience on major projects that include airport runways and infrastructure, motorways, bridges, and sports tracks, Mr Carroll explained they have seen a shift in demand for their services based on the accuracy they are able to deliver.
“Two years ago, I would say our work was 80% road infrastructure and 20% airports, but nowadays it’s a more even split between the two,” he said.
Mr Chamberlain added: “I think that shift is due to our proven track record with our customers of achieving the higher accuracy that airports require, where you’re looking at vertical tolerances of plus/minus five to seven millimetres – compared with roads where it’s ten.”
“We have a tried-and-tested workflow and process that is rigorously accurate and NATA (National Association of Testing Authorities) accredited, so our clients can trust in its validity,” Mr Carroll added.
On any project, whether resurfacing or a new build, the Aptella team always begins with a survey of the existing surface. This is used to compare against any previous surveys that have been done on the job, as well as allow for pre-works volume calculations, cut and fill and so forth.
For road projects, the team performs a pre-test using a high accuracy laser profileograph fitted to the body of a car. This scans the existing surface to calculate a bump count, or International Roughness Index (IRI) count.
“It’s important that the figures and calculations are meticulously checked because our clients have signed a contract that dictates the amount of asphalt for the job,” Mr Carroll said.
In some cases, Mr Carroll explained, the original survey could have been done years before the project is ready to start, so there is potential for significant variations to the original design. In other scenarios, the team has picked up on errors in the original survey due to the use of different methods.
“Our pre-work survey gives peace of mind that the agreed amount is correct to avoid potentially huge cost blowouts. If there is a discrepancy it can get resolved before any asphalt is laid.”
The pre-works data also serves as a point of reference for all parties that can be referred back to if anything does go wrong during construction.
“This stage of the project is also an opportunity to identify and survey any failures in the runway or road for the client to review,” Mr Carroll said. “The issue can be raised with the project owner so that they are aware and can make any adjustments to design if they choose to. If the surface fails in 10 years’ time, for example, everyone has a record to prove that it was a pre-existing fault and not due to their work.”
In some cases the Aptella team is engaged part-way through a project, but the process remains the same in terms of beginning with a new survey. “Although we’re agile and adaptable to accommodate all the challenges paving jobs inevitably throw up, one thing that’s a non-negotiable is our independent survey methods,” Mr Chamberlain said.
He added that they can come onto a job that is only 40 or 50 per cent conformance to design and turn it around to achieve 98% conformance. “We will never accept survey data that is not done by our team.”
After pre-works surveys, Aptella can be asked to perform other survey work to compare as-built data to design, as well as calculate milling to depth numbers if they are taking up the existing surface. Alternatively, the team calculates overall fill numbers for paving straight over the top of the existing surface.
Other services that might be required include setting out service locations, core hole testing, pick up location of underground electrical or other services, and line marking pickup. AGL lighting is another important asset to accurately set out.
If milling is to be done on the job, the next stage for the Aptella team is to mark out the milling design and verify its accuracy through as-built surveys.
Next, the asphalt paving begins, with multiple layers depending on the project design. “The more layers that are laid, the better the result at the top, because you have time to identify and compensate for any errors,” Mr Chamberlain explains.
After each layer is paved, the survey crews perform conformance surveys. For airport jobs, there’s usually a need for daily CAD outputs and volume reporting to demonstrate what’s been laid. At the end of the job, Aptella provides an as-built package with everything that has been done on the project.
Often there isn’t the luxury of completing the paving in a linear process, however, because the runway or road needs to stay open during the life of the project. The asphalt is ramped at the end of each shift to allow for a smooth surface and to correct any height discrepancies between the new and existing surface. The ramp is then milled out and paved over the next day.
“There are so many variables in paving that you have to accommodate and adjust for,” Mr Carroll said.
“With roads we’re often working in confined spaces and to extremely tight timeframes, so it can be a high pressure environment,” Mr Chamberlain said. “We’ve got an optimised workflow that’s tried-and-tested.
“As soon as traffic control is in place our crew is quick to fix our PaveSmart system to the paving machine(s) and begin the first survey resection, which is usually in 200-metre increments.”
The numbers marked out during the survey are then input into Aptella’s PaveSmart system, a unique variable depth paving control solution that eliminates the need for stringlines and ensures smooth, accurate material placement.
For each layer the team inputs variable measures of asphalt allowing for compaction, mix of material, temperature and so forth.
Behind the machine, the team also dips the material to check that the levels laid are accurate. “In theory, the numbers the surveyor puts down, the ones entered into the PaveSmart system and the ones measured when dipped all match up,” Mr Chamberlain said. “If they don’t, our expert operators can make small adjustments to further dial in the results.”
“But no matter how well calibrated the machine there are always factors that affect the numbers, including machine speed, temperature of the mix, whether the screed is in or out, and so on. There needs to be human intervention to interpret and adjust to the unique circumstances on any given shift.”
Now, with the integration to Aptella’s broader technology portfolio, Mr Chamberlain said there is further opportunity to optimise different aspects of the paving process. “Topcon’s milling machine control, for example, can assist with accurate variable depth milling to reduce rework. Plus there’s the ability to use thermal mapping technology in conjunction with PaveSmart to check if the mix is running hot or cold, and intelligent compaction for the rollers to increase the accuracy of compaction patterns.”
Mr Carroll said that the team regularly finds the original paving design is not physically possible, or extremely difficult to achieve, particularly over multiple runs with a machine. “A paving screed can bend a little bit, but not a lot, and we often come across super elevation areas where they cut across two or three lanes, changing from a two-way crossfall to a one-way crossfall.”
Aptella’s team can advise of design optimisation in these cases to achieve similar outcomes but with a design that is built around the paving runs so that it’s achievable.
Mr Chamberlain explained the Aptella team works closely with the client’s paving crew for every shift to ensure that other critical factors such as the rolling pattern are all optimised too. Detailed reporting is submitted daily to keep clients informed, helping to identify tolerance levels and optimise any design changes. The team is often involved in consulting work to analyse the data and design and recommend future improvements or other recommendations.
“I think that’s what our clients appreciate most about our working relationship,” he said. “It’s definitely not an ‘us and them’ approach, but an ‘us with them’ one. That applies to the shift workers on site and the project management alike, we are always working together to optimise the design and get the best conformance possible as a team.”
Mr Carroll agrees: “Our experience from so many projects and having worked with so many clients, means we’re in a unique position to help not only collect the data and complete the job, but also interpret the data and make recommendations to achieve results more efficiently and cost-effectively,” he said.
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