New emphasis is being placed on the use of the observational method. But what is stopping its wider use in the industry?
Since the launch of new embedded retaining wall design guidance last year the industry has been encouraged to use the observational method. But why has it not been more widely adopted? At a recently convened round table in association with Mabey, consultants and contractors discussed how the industry could benefit from the observational method, and questioned what the barriers and drivers were in adopting the technique.
Arup director Asim Gaba, who is lead author of the new Ciria C760 guidance on embedded retaining wall design, which promotes the observational method, kicked off the discussion citing the benefits, including cost, programme and time savings.
“It results in a much safer outcome and a much better managed process,” he argued. “It ends up with a highly collaborative environment, and most things we as professionals would want to do.”
Using Crossrail as an example, Gaba went on to explain that if the method had been used from the start of the project, there could have been cost savings of between 20% and 30% on some structures. However on a smalle rjob, he argued, it was unlikely savings would be enough to offset the cost of the additional vigilance and design.
Wentworth House Partnership director Tim Lohmann agreed there were huge benefits, but the industry was poor at communicating them. He argued that one of the greatest benefits of C760, and of using the observation method, was that the industry could continue to learn.
“The more we measure, the more we learn,” he said. “That is the joy of the observational method. The fact that we fail to report and record it needs to be addressed.”
Winning client confidence
If the savings are apparent, the roundtable was asked why is it sometimes difficult to get the client on board when using the observational method.
“It’s about being grown up when discussing things with our client,”argued Lohmann. “The observational method isn’t that we [the consultant] will take the saving, it is that there is a risk situation and there could be a saving if we don’t have to need to execute part of the design. The win is that we all win, and everybody who works on the scheme gets a benefitfrom using the observation method andthere are savings to be had.”
Lohmann said he thought a bigger issue was that triggers were set too low because people don’t trust the observational method.
“We often see triggers that are set very low to implement the next phase and that can be challenging,” he said.
Gaba argued that the method could only work if the right procurement arrangements and contractual set up for it were implemented:
“It doesn’t work if people are not allowed to collaborate and work together. It has to be a collaborative effort.
”Kier civil engineer Olivia Perkins agreed: “On Crossrail, the observational method was initially not allowed.However it was possible to use it at Tottenham Court Road and we were able to see the substantial benefits. Not only with safety, sustainability, but also the programme and cost savings benefits.
”Because we had the appropriate control process and monitoring in place, we were able to use the method, however it required open minds and collaboration between a number of teams.”
Sharing data across the industry
CGL director Mark Creighton said the industry was not sharing as much as it should or probably could. Using London as an example he went to explain how sharing data on schemes across the city could benefit all.
“We think we understand London ground conditions, but there are things we are continuing to learn as we devlop deeper. “People are holding onto the pieces of the puzzle and not sharing them. They arereluctant to share geotechnical information and it’s a terrible shame that all the data we are collecting is just sitting in cupboards. There is a huge opportunity being lost.”
Mott MacDonald project director Rob Talby thought borehole and factual ground investigation data should be released once immediate commercial matters had been resolved. “For teams who use that data in ten or 20 years’ time, all they have is the borehole and the factual data. They are not aware of which borehole is a contentious one from a previous geotechnical baseline report discussion, because that is between the team at the time.”
“We’ve got to the situation where nobody benefits commercially,” argued Mabey senior engineer Jon Barritt. “If this were all public data we would be in the situation where everyone would benefit from the data.”
Lohmann said he thought that we were moving to a new era of cheaper data recording and capture and should be capitalising on that. “We are not just poking inclinometers down tubes any more,” he said. “We can measure those inclinations better, cheaper and live.
“This is the opportunity as an industry to develop and define what we want measured and who will deliver it.”
Improving the brief
“There is a lack of understanding of what these numbers mean and how restrictive they can be,” pointed out Perkins, describing the miniscule measurements for permitted movement sometimes specified, and causing a barrier for using the observation method.
“The models for calculating these figures are often very conservative and there is a lack of time spent back analysing what actually occurs or learning from recent projects on what is possible or permissible.”
It was agreed around the table that a lack of long term baseline monitoring ahead of construction made it difficult to improve specification and design briefs.
Creighton felt that this was especially true on privately funded schemes. “For infrastructure projects we can afford to invest in that monitoring, but in a commercial building project it is not until a contractor is appointed and they are going to start in two or three weeks’ time,” he said.
“There just isn’t the time to have six weeks of baseline monitoring before the programme kicks in. “It comes down to clients being willing to invest in monitoring from the onset rather than just seeing it as a protective measure.”
So could sharing data help reduce the need for baseline monitoring?
Byrne Looby director Richard Thiemann said that data sharing would help. “If that information was out in the public domain, then everyone would know the surrounding structures can move 10mm or 20mm,” he said. “This would help them realise that setting a 1mm trigger measurement is unworkable.”
Perception of the industry
Could the perception of the industry be affecting the adoption of observational method?
“We’re not going to change the perception of our industry overnight. It is about striking an appropriate balance between risk and opportunity to realise benefit for all,” argued Gaba.
“As engineers we’ve been talking about engendering truly collaborative working to implement the observational method, to achieve this for as long as I can remember, and it doesn’t seem to change very much.”
Gaba thought it was the industry’s responsibility to promote this: “We need to influence and stress the benefits of this type of approach, where everybody benefits and gains something from it. Not only the industry, but the profession, learn on an ongoing basis.
“The key is to try and come up with a different approach, or try and influence a change in the procurement arrangement or environment that currently exists.”
Careys technical director Sam Wong, said that the more we share about the observational method, the more confident the industry would become. He added: “The more that is shared, the more confident we would be with the observational method and people would understand more.
“At the moment, because we are not sharing information, as there is no money in sharing that knowledge or lessons learned, this isn’t happening. We need to be more confident in using the method.”
Creighton acknowledged that his organisation did share their project data, but like for many in the industry it is not purely altruistic. He explained: “As a business, we share our experiences as a form of marketing. Subliminal marketing maybe but it is brand awareness.”
Quality of data
Cementation Skanska chief geotechnical engineer Dimitrios Selemetas, felt that the industry should not be collecting just any data. “It is easy just to measure movement but what is difficult is to find the whole story,” he said.
“Knowing the measurement is one thing, but understanding what is the excavation level, what else is happening on site, what is the weather like. We don’t just need data, but good quality data.”
“It’s a big ask,” responded Creighton, who said he thought that there was not enough time for someone to collate that level of detailed information. “There are copious records and someone needs the time to plot the timeline and relate it back to the movement data.
“Projects are so complex, and to go back through all that electronic or paper data is a big task and most of time there isn’t anyone with time on their hands to manipulate it.”
Mabey engineering director Dave Holland explained that in the future it could become easier with live BIM. “At Mabey we have taken the BIM model and imported it into a custom 3D engine and created a model with a timeline,” he said.
“We can see how the structure behaves, add the metadata to the live building information modelling (BIM), and scroll across a timeline to see the effects and cross correlate between projects on one model. We are not far from having this data.”
Observation method in the future
“HS2 will make a big difference,” explained Gaba, “but only if we articulate the benefits from its use in a truly collaborative working environment. The improvements will only get better as time goes on. The more we use the observational method the more effective it becomes.”
Lohmann suggested that we could be seeing on average 25% to 30% more efficiencies in major infrastructure projects using the observation method. More specifically in geotechnics, he estimated 15% to 20% savings in the next 10 years.
“But we are in danger of plodding the same path. Major infrastructure projects can be the big winner but there will be little improvement, unless the appetite is there to change.
“Where is the courage going to come from? From clients? Because as contractors, we are ready.”
Around the table
Jon Barritt senior engineer Mabey
Ben Chivers engineer Mace Group
Mark Creighton director CGL
Asim Gaba director Arup
Dave Holland engineering director Mabey
Wilson Kesse project lead engineer Laing O’Rourke
Tim Lohmann director Wentworth House Partnership
Olivia Perkins civil engineer Kier
Dimitrios Selemetas chief geotechnical engineer Cementation Skanska
Claire Smith editor Ground Engineering
Rob Talby project director Mott MacDonald
Sam Wong technical director Careys
Richard Thiemann director Byrne Looby
Sita Shah civil engineer Mace Group