Implications of BIM and infrastructure investment on the efficient delivery of earthworks by machine control were among the topics discussed at GE’s first round table debate.
In the same way that everyday items can now be produced by 3D printing, earthworks concepts can also now be delivered in a similar way using the latest machine control technology. This was one of the emerging themes at the recent Topcon-sponsored round table event in London.
The discussion looked at use of machine control technology for earthworks in the UK and the barriers that exist to wider use. Guests at the event, chaired by GE editor Claire Smith, included clients, contractors, consultants and manufacturers – and they all agreed that machine control was the future.
The beauty, potential and passion for machine control in earthworks projects was underlined in the opening stages of the event, with examples such as Northumberlandia discussed. Machine control simplified the creation of this 30m high sculpture of a reclining lady from 1.5Mt of material at a former coal pit near Newcastle, and the technology facilitated a much more natural design. This is something that landscape designers are demanding more frequently, the group established.
While there are some inspiring examples of the use of machine control, the UK has lagged behind the rest of Europe in adoption of the technology, but is this still the case? The panel reluctantly admitted that Europe had been an earlier adopter than the UK, but contractors this side of the channel are quickly catching up to, or already equal in, providing machine control.
The table agreed with Ramboll geotechnical director Stephen West when he described his experiences of attitudes in Europe, which do not often include the need to test machine-controlled results. Opinions were somewhat divided on the extent of tests needed to verify and validate these results in the UK, but it was clear there are still situations where testing would be necessary.
CA Blackwell director Niall Fraser said machine control is a fantastic tool to be able to demonstrate compliance through a quality system and although it’s great to be able to give a report of the machine’s performance – number of passes, speed, the layer thickness – all compaction is relative to benchmark data. He added: “I think that is why it’s received greater adoption in continental Europe. They are blessed with less variable and generally better ground conditions and they also don’t have the unpredictability of the weather, certainly in the lower-latitudes.”
The difference in geology means that not every aspect of machine control in Europe can be applied in the UK for earthworks. Topcon machine controls sales manager Dan Smith pointed out that machine control has been used quite successfully in continuous compaction control (CCC) in Europe. He said: “It’s coming more from the blacktop side where you’re looking at a number of passes and uniformity.”
Arup associate director Alan Phear agreed that CCC works quite well on a granular fill, a sub-base or asphalt but added that it can give misleading results for cohesive or clay fills where excess pore pressures are generated during compaction. He added: “Many of our materials in the UK are clays or cohesives and so CCC has limited application here until the technology gets a bit smarter.”
WEAK SPOT ANALYSIS
Both Phear and Skanska chief engineering surveyor Mark Lawton approved of CCC for weak spot analysis in the UK to find the areas in a fill layer with poor compaction. Provided that the fill material is consistent, compaction equipment can target the insitu density testing in the weak areas. This means a more efficient density testing regime and more efficient use of lab testing resources.
What is clear is that the willingness to adopt machine control exists within the geotechnical and construction sectors of the UK, but geology is not the only factor businesses have to look at when choosing whether to invest. The inclusion of innovation options in flexible contracts, the previous uncertainty of long term infrastructure projects in which to invest such resources, and the flow and form of digital data to and from the client were all brought up over the course of the evening.
The increasing complexity of data used in building information modelling (BIM) and 3D models, due to the volume of information and variety of software used, creates a particularly frustrating problem. Walters design and survey department manager David Broughton summed up the problem when he said: “The information is all there but we need an index to know what layers to pull out. The actual size and numbers of points contained within the layers in a model we have been getting over the last six months have gone up in size on one site by a factor of six. Now we have to split the model because we’re running out of what the machine can deal with.
“As an earthworks contractor it’s getting harder to get the information out, rather than easier.”
Lawton added that while designers were happy with the improvements in BIM, the large and complex data formats were unhelpful for “dumb” machines. At the operational end only one specific piece is needed and it takes months, and sometimes several separate software houses, to be able to simplify these models.
Topcon business manager in positioning instruments, David Bennett, questioned whether the amount of data within a design is reaching breaking point. The answer to this is not apparent and the amount of work being done through computers raises more issues.
Atkins chief geotechnical engineer Paul Nowak added that there’s also a loss of engineering judgement through greater use of models produced that are then programmed into plant. “We will create something that is effectively an engineering tool rather than useful information,” he said. “Coming from a geology background, if you model all your boundaries as straight lines, you won’t get an accurate model, as it will ignore geological processes. The responsibility then goes back to the designer for interpreting the data from an engineering 3D model to determine its accuracy.”
2D VERSUS 3D
There are two levels of machine control – 2D and 3D. 2D means controlling the machine hydraulically to a level, while 3D gives the positional information to the driver.
2D machine control involves the use of slope sensors, laser or sonic trackers to provide a height reference and slope reference to the operator. This is used on bulk earthworks, house pads, sports grounds and some road activities.
2D only requires putting in a single peg before dialling in the gradient and slope distance. This takes men off the batters and worked well on the M25 widening project.
3D machine control is designed for complex engineering designs and involves the use of GPS to calculate a 3D position for the machine’s tools. This position is then used by the system to automatically or manually guide the machine operator to the 3D design they are working to.
The input, and therefore responsibility for data, impacts again on testing as the contractors cannot be held accountable for validation if they haven’t created the model. The collaborative approach seems to be the most productive solution in the short term. The more data, and communication, that flows between construction partners at an early stage, the more useful machine control can be.
Highways Agency geotechnical team leader David Patterson concluded that it was possible to see how unintended barriers to the consideration of innovation, in industries such as earthworks, can arise if the contractor does not have a direct role in the review of innovation opportunities with the client, designer and construction team.
Mott Macdonald principal engineering geologist Antony Drake questioned whether the industry has taken enough advantage of the shift in contract set up of the last 10 to 15 years, and added: “Are we using the opportunities in the contract set ups to make the changes we’re talking about?”
So does this mean machine control has a bright future in the UK and the days of stakes marking out sites are over? Buckingham Group Contracting head of geomatics Nick Smith said there was still nervousness about machine control. “The works managers are reluctant [to use machine control] because they haven’t got the pegs in the ground,” he explained. “They’ve got no frame of reference.”
While there is an increased efficiency from not waiting for wooden stakes to be surveyed into position, the need to clearly illustrate a model for all involved is not yet met in machine control. While the table understood the current need for stakes they conceded that an augmented reality application, giving access to the driver’s screen to the foreman and other parties, would be an apt modern replacement.
If anything this highlights how far the industry has come in embracing machine control and maximising its potential. The economic situation of the last five years has not been ideal for large-scale investments but with growing demand for earthworks on large UK infrastructure projects, the ground engineering industry is positioning itself to deliver the efficiencies that machine control can achieve.
While the end of the night brought consensus on the return on investment for machine control systems for the table, there were still others within the industry to convince. Komatsu Marubeni machine control manager Ross Smith suggested a set of case studies that detail exactly how much a machine control system can generate in a real-life environment and added: “Customers see an up-front cost for a machine control system and don’t necessarily see how much that will save them in the long run.”
The long term is where the benefits of machine control will bear out. With more guarantees of workload, improved data flow and new technological applications, there are still more advantages to be leveraged. Walters managing director Nick Richards said: “We got through the early jittery stage because we could see that the advancement of technology was not going to stop and that the equipment empowered drivers to work.
“The industry is going to move quickly, over the next five to 10 years, into new ways of working. You’ll be left behind unless you’re part of it. Technology is going to be to the fore as we move forward. You’ve got to be in there to be part of it.”
Morgan Sindall managing director Colin Eddie summed up the evening thus: “I am sure that the UK will be a fertile breeding ground for good ideas that will deliver efficiency savings. However, the clock is ticking and all these good discussions will be for nothing if they are not implemented soon.”
STANDARD IN DEVELOPMENT
European standards for earthworks are currently being developed and round table guest, Arup associate director Alan Phear, is currently working on this with standards body BSI.
The B/526 committee is responsible for drafting standards for earthworks and providing UK input to the European CEN/TC 396 Earthworks committee.
Phear said: “It aims to create a harmonised approach to earthworks across Europe. At the moment most countries follow the same general principles, but each has its own particular national practices.”
The European board intends to provide standardisation in terminology for earthworks, test methods, classification systems of soils and rocks suitable for use in embankment construction, characterisation of extraction, design of earthworks and quality control of works and monitoring.
It is being developed to share European knowledge and experiences, provide better interpretation in contracts for earthworks contractors and designers, and to deliver a base for establishing common criteria of performance-based requirements as well as future research.
It is difficult to know exactly what changes this will bring to the UK construction industry, but the harmonised approach is expected to have a positive impact across Europe. It is expected to raise awareness of the acceptability of machine control in works such as continuous compaction control using vibrating rollers.