Groundworks & Infrastructure: Breaking new ground

Tunnelling on the Victoria Station Upgrade in London has progressed twice as quickly thanks to BIM, compared to similar schemes

How is BIM changing practice within the piling and ground engineering sector? Will Mann talks to the contractors and consultants using the technology.

By its nature, ground engineering is one of the most challenging sectors of the construction industry. Finding ways to visualise and map unknown obstacles that lie beneath the ground is complicated and time consuming, designing and planning construction projects around them even more so.

But BIM may be changing that. One of the biggest infrastructure projects to use the technology to date, and an exemplar for BIM in the sector, is the £700m Victoria Station Upgrade (VSU) in central London.

The scheme includes construction of a 400m tunnel between ticket halls. “BIM has enabled us to double production rates on the project,” says Taylor Woodrow project manager Craig Prangley.

“Compared with similar tunnel jobs in the past, tunnel construction would typically proceed at a metre a day; here we have achieved two metres,” he says.

Alasdair Henderson, chairman of the Federation of Piling Specialists (FPS) and a divisional director of geotechnics specialist BAM Ritchies, is similarly enthusiastic about BIM’s potential for the sector.

“We can improve productivity by 10% using BIM simply through better processes – capturing as-built data on tablets, feeding information about piles, ground anchors, grouted injections and so on into the model saves the need for checking and reanalysing the information manually,” he says.

“And that’s not factoring all the benefits from using a 3D model to help upfront planning. BIM allows a more structured approach because all existing asset data can be combined with new information, such as from borehole investigations, in one model.”

This has been an important factor on the VSU scheme. Consultant Mott MacDonald is another member of the project team, and geotechnical engineer Alan Willoner feels that an important advantage of BIM is that it “provides better clarity about the spatial position of the known data”.

He elaborates: “3D ground models are not necessarily more accurate than the original 2D sections as they are reliant on the same data. However, bringing all of this already existing data and information into one ‘geo-referenced’ environment allows the data to be better understood.”

Compensation grouting on the Keller-BAM Ritchies Crossrail projects at Tottenham Court Road and Bond Street has used real-time monitoring

Willoner believes that Level 2 BIM is most likely to add value on “complex grouting schemes, such as jet grouting, or compensation grouting” in urban environments.

Phil Hines, group managing director at Bachy Soletanche, says: “If you are working in a congested area, where there are a lot of underground obstructions, it is essential to have a 3D model to avoid hitting services and existing foundations.

“We have been using 3D models to plan grouting for 20 years. But the difference with BIM is it allows us to share and make better use of data to enhance our operations.”

With piling, use of BIM may prove trickier, according to Willoner. “It is difficult to say what value can be added in the majority of UK piling jobs, as ground variability is generally high and often requires manual verification of pile lengths.

“There may be opportunities for BIM to improve productivity in piling schemes where the design of ultimate compressive resistance is determined directly from ground test results, rather than by calculation. This has been a common approach in other countries such as Holland,” he says.

The next steps in exploiting BIM technology for ground engineers may involve greater use of the models in real time.

“We are using real-time monitoring for compensation grouting on our Crossrail contracts at Tottenham Court Road and Bond Street, in joint venture with Keller,” says Henderson. The monitoring is provided by Keller subsidiary Getec, and was originally developed in Germany.

Prangley says monitoring ground movements in a real time environment would have been beneficial on the VSU scheme. “We were only 2.7m away from the Victoria Palace Theatre and it would have helped if we could monitor vibration and noise levels in real time,” he says.

“We had automated text messages to notify our engineers when they were above a certain level, but obviously the future would be to automate and link that into the BIM model.

“We never really exploited the model’s possibilities in real time – we would still take drawings off the model and print out for our site engineers in 2D,” Prangley adds. “We need to give our site engineers the technology so that they can see the model as the project progresses in real time, on tablets.”

BIM has helped plan construction on the complex and congested Victoria station site

Another advance Prangley predicts is greater automation of plant, again in a real-time environment, a view shared by others in the sector. Other future developments are likely to include greater use of 5D and 6D BIM.

 At VSU, this is already happening to a degree, where quantities for materials are being drawn off the BIM model, and its asset information will be used by London Underground to plan the long-term management of the station.

The use of digital sensors, to provide information about asset performance, will also become more commonplace on infrastructure projects, according to Henderson. (See also, “Infrastructure gets smart”).

“On BAM Ritchies’ Loch Arklet Dam project in Stirlingshire, which is a fairly conventional ground anchoring job, we have installed barcodes in the tops of the anchors which provides vital information about when it was bored, installed, grouted – and will be incredibly valuable for the asset manager,” he explains.

But despite all these advances, ground engineers often face blockages to using BIM further up the supply chain. When working as subcontractors, they report limited interest in BIM among main contractors.

“There is a high degree of BIM awareness among FPS members, but based on BAM Ritchies’ experience, we are seeing less than 20% of tenders calling for BIM use,” says Henderson.

Hines says the same is true of Bachy Soletanche’s experience. “There is a lot of talk,” he says. “But not many main contractors want to interface with us on a high-level BIM model. Rarely do we supply information into a common model.”

“We need to collaborate better and BIM presents an opportunity for us do this,” says Henderson. “There is huge operational skill among FPS members, but too often we see what we do or what we can do replicated at tier one level.”

Getting past that obstacle may prove to be harder than learning how to use the BIM technology.

Digital rigs? The potential for automation in ground engineering plant

Use of BIM to plan jet grouting at Victoria station

As CM reported last month, digital technology is beginning to emerge in earthmoving equipment, to automate the digging process – so why not in piling and grouting rigs too?

Based on his experience using BIM at Victoria Station, Taylor Woodrow project manager Craig Prangley believes automating the use of ground engineering plant will become more commonplace.

“We took data from the BIM model to orientate grouting masts at the correct angle, but we did it manually,” he explains. “But now we would probably send data from the model to the rig, and use GPS technology to align the masts.”

Alasdair Henderson of the FPS also envisages greater automation. “By comparison with another sector, we operate quarry drilling rigs which are fully robotised,” he says.

“They have fuel consumption of just 50% of the levels of manually operated rigs. They also have a longer consumable life. Because they are automated, the driller can focus more on the specification and outcome rather than how the drill is performing.

“Use of BIM and digital technology with piling and grouting equipment could yield similar big savings on fuel, plant wear and tear and all-round productivity and efficiency. The fuel consumption, the torque level and the feed pressures could all be pre-programmed.”

Mott MacDonald geotechnical engineer Peter Fair says: “In terms of plant movement, BIM technology can certainly assist with the planning and movement of the rigs. With the transfer of data and common data formats becoming more prevalent, then the position and depths of piles could be uploaded onto the machine direct from the design files, reducing time and potential human error.”

“There may be some instances where ground conditions are sufficiently uniform for the full automation of rigs in the future, particularly for friction piles.”

They will be the exception, Fair thinks: “It is unlikely that piling in UK will move towards full automation of rigs as ground variability between known data points generally requires experienced judgement on site.”