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Interview:The golden touch

Len Threadgold is a director with Geotechnics

Despite working in the ground investigation sector for over half a century, Len Threadgold believes there is still much to learn.

The ground engineering industry should be re-thinking site investigation design, practice and procurement, according to Geotechnics chairman Len Threadgold who won the John Mitchell Award in 2017. He will draw on his experience working in the ground investigation sector during his award lecture to look at the challenges facing the market and how the business could be advanced.

“It’s fascinating,” says Threadgold, explaining why he chose to work in the ground investigation industry over 50 years ago. “What people don’t really understand is that every single civil engineering project is a prototype. There may be similar structures, but the ground conditions are going to vary and that is what makes each one unique.

“There is the deposit itself, but also the history of that deposit. What is the stress history? What has been the effect of glaciation for example? It’s the standing back and thinking laterally that makes the profession so good.”

“What people don’t really understand is that every single civil engineering project is a prototype”

It is this lateral thinking that Threadgold will be speaking about at the Institution of Civil Engineers on 24 January, when he delivers his John Mitchell Award Lecture. In his lecture entitled “Re-thinking Site Investigation Design, Practice and Procurement”, Threadgold will challenge the industry to take a step back and think more about how ground conditions and structures interact, and how any form of investigation needs to match the specification of the structure.

“The unknown is the ground,” says Threadgold. “We all know how much building materials cost, but the ground is the unknown. You may have an idea of what is there, but you need to find out in more detail depending on what it is you are investigating.

“We don’t tell the ground what to do, we ask it nicely.”

This knowledge is key to efficiency, often cutting down construction times, and the safety of designs, he believes.

“It has always been my view that knowledge is much better than ignorance and people design on the basis of ignorance if they ask: ‘it will be alright won’t it?’,” Threadgold says.

“It is indefensible if someone designs a very large building and puts it on the ground about which very little known, purely because they were okay last time. That is not a good strategy.

“It might cost ten bob more to carry out site investigation, but you are getting a whole lot better value,” he adds. “If you think knowledge is expensive, think what the cost of ignorance is.”

Threadgold believes that increased recognition of the importance of ground conditions is needed across the entire construction industry; from scheme funder, architect, client, to the engineer and contractor. It is collaboration between everyone involved that will help balance expectation for the end product.

“It is getting that message over topeople who see site investigation as a commodity that they may purchase, like a television. But it is not, it is a process. A necessity,” he says.

Threadgold believes that although the industry has great track record, it is inhibited by the way its services are procured.

“Sometimes it is procured very late on in the day. People think: ‘oh we had better do an investigation’, rather than thinking: ‘we should have done this much earlier in the process’,” says Threadgold.

The industry must get further up thefood chain, as site investigations are often seen as an optional extra that can be done at the cheapest price.

“It is my view it is the most cost effective and risk management action that you can ever do,” he says. “It is in every sense fundamental. “Some people will see it as a pain, but how else do you design?“ You have two options, you design very optimistically and risk failure, or design very conservatively and risk a significant increase in costs and delays to your project.

“The ideal would be to optimise the design to find out about the core of the ground in a structured way, so that this knowledge is able to be used in an assessment.”

Threadgold argues that this understanding can be greatly improved by increased monitoring before, during and after a building is completed. In particular, when predictions are given for ground movement after an investigation.

“We make strident predictions where we say we can’t have this ground settle more than x, or we can’t have this ground tilt more than y,” he says. “Often, after all this work is done, and to meet the criteria, we are going to have to pilot without any checking that the values are realistic.

“If you think knowledge is expensive, think what the cost of ignorance is”

“Would it matter if the soil settled twice as much, and the answer is we don’t know.” It is the monitoring of a building during and after construction that could fill this void of information, but that involves the sharing of information.

Something that isn’t always possible. “We make these predictions so let us monitor what happens,” he says. “Not to catch anyone out or point the finger. But sharing this information is difficult.”

This is something which Threadgold believes should be easier, especially as monitoring becomes cheaper to implement, and more data can be collected than ever before. This can help with collaboration.“Collaboration is key,” he explains. “Historically a consultant designs their project, then they ask for boreholes,and will instruct the contractor. Thec ontractor will do it and return the results to the consultant who will make all the decisions. Today it is different.”

At Geotechnics, which Threadgold founded in 1983, the situation is poles apart.

“Ground engineering isn’t just a dot on a path on the way to design, but an essential part there from the beginning”

“Each of us has different experiences, and I wouldn’t tell people this is the way to do something,” he explains. “I would ask them. I would use that expertise.“ This is what needs to be done industry wide. It is the rethinking relationships.”

It is the budget allocated to site investigations that undermines their importance, argues Threadgold, using a figure from research that ground engineering expert Stuart Littlejohn undertook.

“You are making a decision about the fundamental part project on 0.021% of the project cost,” Threadgold adds. Using UK motorways as an example, Threadgold explains that of the 35% of projects where costs overrun, half are due to unforeseen ground conditions. That is17.5% of the cost of the project set against 0.021% of the total cost of the project – 833 times more expensive.

“It is nonsense economics. It is nonsense engineering. Part of the problem is people see it as a cost at an early stage of the project that they are not used to. At the later stages they are used to shelling out millions, but not at the start,” Threadgold argues.

“I bet that the cost of the site investigation is half the price of the opening party. Because it is at a different phase, it is seen as irrelevant.”

It is this rethinking of the industry as a whole that Threadgold wants to herald in his speech.

“Ground engineering isn’t just a dot on a path on the way to design, but an essential part there from the beginning,” he says.

“Fundamental to everything is the ground and fundamental to its behaviour is knowing about it. “By doing investigations, you will never find everything there is to know about it, but you have a much better chance of getting it right.

There is no reason why you can’t design a building that can accommodate whatever the variability is,just as long as you know what thev ariability is.”

After 50 years in any industry most people would be thinking about plans for retirement, but Threadgold is finding it tricky to withdraw. He says: “Are there stresses and strains? Yes there are. Do they sometimes get a bit too much? Yes they do. But I still love it.”

Colleagues in the industry have asked why people do not understand what they do, and have said that Threadgold is preaching to the converted. Threadgold responds: “If you regard this as a prayer meeting then people are going to go out to the highways and byways and promote the cause, think of ways of doing it better, and to get people to understand what they are buying. 

“It is getting that message over,” adds Threadgold, “if it works then I shall have succeeded.”

For more information and to book a place at Len Threadgold’s John Mitchell Award speech on Wednesday 24 January 2018 click here. The lecture will also available to watch live online.

Ground breaking AGS Format 

Back in 1991, Len Threadgold was at the forefront of a revolution. Ahead of its time, the AGS Format was developed by the Association of Geotechnical and Geoenvironmental Specialists (AGS) to improve communication between designers, contractors and clients, by introducing a standard protocol for the sharing of factual information.

“It had to work,” says Threadgold of developing the format. “It had to be a coherent language that everybody understood, that was all that mattered.

”At the time I said to colleagues, that if we agree that is a good thing to do, then it will work. It was created by the industry for the industry. ”This new industry standard bridged the gap between parties working on a project to ensure that geotechnical data could be shared using the same format.

More than 25 years later, it is standard practice across the globe, and all members of a team can use and augment data without delays, extra costs and potential mistakes of entering data in different formats.

By using the format across a scheme, information and data can be easily transferred for use with building information modelling and in asset management, as well as achieving significant cost savings.

Clients such as Highways England, Crossrail and High Speed 2 specify the use of AGS Format on their projects and Threadgold believes if the format didn’t already exist it would need to be invented for the massive infrastructure projects in the pipeline.

“The beauty of using the format is that everybody recognises it. If in 10 years’ time someone wants to add to that, they can. If they want to redevelop the site, they can use that data. It has a certain universality to it. A commonwealth of data. It’s what we ought to be doing to help UK plc.”



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