Case study

Tideway: On the tools

We look at how health measurement scoring systems with leading and lagging indicators have been adapted for the Thames Tideway Tunnel project. 

Tideway-Tideway-West tunnel boring machine_Copyright-Tideway-West
The tunnel boring machine being used on Tideway West. ©Tideway West

The infrastructure provider behind the Thames Tideway scheme in London is racking up a first in occupational health (OH) provision. Tideway, the company appointed by Thames Water to build, maintain and operate the 25 km tunnel below the River Thames to relieve the capital of its sewage and rainwater, has mandated an OH service for the entire seven-year project – an arrangement unknown until now in large-scale infrastructure projects.

Tideway has written the requirement into the works information which forms part of the framework agreement with the main works contractors (MWCs) that will build the three tunnel sections in separate joint ventures (see Thames Tideway Tunnel box below).

This increased focus on ill-health prevention involves employing a single OH provider for clinical services at the three main drive sites and procuring occupational hygienists through a specialist subcontractor, Park Health and Safety Partnership, to advise on and monitor occupational health exposures.

In another industry first, the £4.2bn “super sewer” development, on which tunnelling will begin in the spring, is the subject of a longitudinal study by Loughborough University and funded by IOSH to track and inform occupational safety and health (OSH) leadership, policies and practices at Tideway, its MWCs and the subcontractors.

Thames Tideway Tunnel

Tideway’s new super sewer will capture the huge overflows caused by London’s antiquated sewerage system. The capital’s Victorian sewers are overloaded and release millions of tonnes of raw sewage into the tidal section of the River Thames every year.
Due for completion in 2023, the project will run a 7.2 m diameter tunnel for 25 km up to 65 m below the river. The system should be able to capture, store and transport the combined raw sewage and rainwater discharges that overflow into the Thames for at least 100 years.
Construction is divided into three sections: west, central and east and three joint ventures comprising eight tier-one contractors will undertake the building work. The partners for the west section are BAM Nuttall, Morgan Sindall and Balfour Beatty. Ferrovial Agroman UK and Laing O’Rourke Construction are the main works contractors for the central section. Costain, Vinci Construction Grands Projets and Bachy Soletanche will build the east section.
To read more about the project visit: www.tideway.london

Researchers rarely forge relationships with schemes on this scale and in construction few projects are so lengthy. Most research is carried out only after project completion.

“One of the problems of cross-sectional research looking backwards is that you are relying on the selective memories of individuals,” says Professor Alistair Gibb, who heads Loughborough University’s research team on Tideway. “In some cases, those individuals weren’t in post anyway and corporate memory is poor.”

A major problem with the retrospective approach is the temptation for participants to talk only about the successes and ignore the decision-making stages. As Gibb points out, longitudinal research provides a chance to track how approaches are tested and changed, creating valuable data to ensure missteps are not repeated in other large projects.

“What we are trying to do is [look at] how these [big projects] work in practice,” he says. “How does policy become a reality on the ground? How do people cope when things go wrong? How do we build resilience in organisations or how do we develop the resilience that is already there so they can cope better than they otherwise would?”

By studying the Tideway Tunnel’s evolution Loughborough’s researchers, embedded in the three main drive sites, will offer real-time advice that Tideway can use to develop its OSH processes. The lessons will also be shared with the wider industry, most significantly on projects such as the Crossrail 2 rail link and the Lower Thames Crossing tunnel between Kent and Essex.

Tools of the trade

Alistair-Gibb-Loughborough-University-research-team-headBefore preliminary construction began in February 2016, Tideway drew up performance indicators to measure OSH performance across the three tunnel sections. But it needed a tool to measure OH performance and identified the health impact frequency rate (HIFR), which had been designed and piloted during the construction of the Olympic Park for the London 2012 games and was adapted further during work on the first Crossrail scheme in London.

The HIFR is the health equivalent of the accident frequency rate (AFR) measure and works by counting workers’ exposure to unmanaged health risks such as dust exposure without water suppression or respiratory protective equipment.

Eric Ball, partner and occupational hygienist at Park Health, was brought in to lead the hygiene team for two of the Tideway contracts. The hygienists began using the HIFR tool in July 2016.

Findings from the hygienists’ weekly two-hour observation tours were fed back to the local project teams and to Tideway so they could act on the findings and use the data to programme training.

Ball says being on site familiarises the hygienists with everyday activities and lets them strike up conversations with the workforce.

He points to an observation at one Tideway site where two workers were breaking ground with a vibrating tool. Both workers were wearing hearing protection and gloves. They were also rotating the work, in line with good practice.

As long as you make enough tally marks across the entire site, you generally get a good feel for whether activities are being managed

“I asked them, ‘What’s the maximum [duration of work] you can do?’,” he says. “They had no idea. They knew everything apart from when to stop.”

It’s this value added by close monitoring that Ralph Ashwood, health and safety manager for the BAM Nuttall, Morgan Sindall and Balfour Beatty joint venture delivering the west section of the tunnel, cites as critical to improving the project’s OH provision.

Artist’s-impression-of-tunnel-cross-section-Copyright-TidewayAshwood says Tideway West’s joint venture partners could do the HIFR measurements themselves but he reiterates the wider benefits of embedding the hygienists in the site team, an arrangement that allows workers to express any concerns to the specialists.

“They are faces on site, they are known and the site teams know what they can offer, what support and guidance they can give,” he says. “Instead of coming to the health and safety team, workers will, for example, phone Eric with control of substances hazardous to health [COSHH] assessments straight away.”

Most of the frontline operatives employed by the joint venture partners had worked previously on Crossrail, so the calibre of the workforce was already high, says Ashwood. They were familiar with ill-health prevention measures and receptive to being challenged further.

“Although Crossrail didn’t have the embedded hygienists to the same extent [as Tideway], they did work hard on health risk management,” says Wendy Jones, Loughborough’s occupational health specialist on the research project.

“Crossrail laid the foundations for what Tideway is doing because they set high expectations so that managers and OSH professionals started to get their heads around, for example, dust management. They did research and work on dust control.”

Ashwood felt that the HIFR, however useful it is for measuring OH exposure, was a negative, lagging indicator, like the AFR. The emphasis on counting incidences of exposure to health risks could suggest the overall picture was worse than it was. He wanted to find a way to record and reflect the hygienists’ observations of good practice.

Finnish formula

Ashwood and Ball looked overseas for inspiration and were drawn to the Finnish TR observation system, which has been used by labour inspectors on construction sites in the country since 1993.

The measurement, which mainly covers safety measures, records on an inspection sheet observations of correct and incorrect practice under six headings. These include working habits, scaffolding and ladders, and protection against falls. The sheet comes with a guidance document with pointers to aid the inspectors in their scoring.

The recommended limit for observations per site visit is 100. “As long as you make enough tally marks across the entire site, you generally get a good feel for whether activities are being managed,” says Ashwood.

Each observation carries equal weight when calculating the safety level. However, the inspectors can emphasise more important areas by increasing the number of observations on specific issues, such as work at height. Once the scoring has been finalised, the correct observations are divided by the correct and incorrect observations. The observer multiplies the total by 100 for a percentage score as follows:




To put this in context, Ball returns to the observation of the two workers using the vibration tool but who didn’t know when to stop even though they were using the correct procedures.

“It would be quite easy to jump on that and say, ‘That’s wrong for vibration’,” he says. “But it doesn’t account for the fact that they’ve got the right tool and they know how to do the job.

“If you just do a negative score, that’s one black mark [with the TR system]. One hundred per cent of my observations of that task are incorrect. But you need to contextualise that and say ‘four observations are good and one is bad’. That is 80% correct rather than 100% incorrect. That’s the main driver for this.”

Ball adapted the TR model, substituting the safety elements with health ones, including noise and vibration, manual handling and asbestos. COSHH was separated into different elements: dust, gases and fumes (including anything airborne) and general direct contact, such as wearing the right type of gloves for concrete pours.

Ball is planning to add thermal comfort and lighting as headings later. “Lighting isn’t a particular issue for us, but it may be when we start to go underground and start [work on] connection tunnels,” he says.

Consistent marks


Tideway Tracer research project

Commissioned by IOSH, a multidisciplinary team of Loughborough University researchers led by Professor Alistair Gibb (pictured above) is undertaking a longitudinal study of occupational safety and health (OSH).
Researchers are working closely with each of the project’s contractor teams (see Thames Tideway Tunnel box above). They will monitor how OSH practices develop in Tideway (the project lead), the three main works contractors (MWCs) that are building the three sections, and the subcontractors.
Apart from the work-related ill-health prevention report which includes the occupational hygiene arrangements and use of the health impact frequency rate tool, preliminary reports have been published on three other aspects of Tideway’s OSH arrangements:
  • Communications assessment – a computer-based English-language tutorial, which is designed to aid OSH communication on site and must be taken by everyone involved in the project regardless of whether English is their first language. The researchers note that links have been made between poor communication and poor understanding and accidents or near misses. 
  • Employer Project Induction Centre (EPIC) introduction – an immersive and interactive induction, which uses actors to take participants through a scenario involving a construction site incident. EPIC allows participants to discuss and influence the scenario’s outcome and is compulsory for all workers.
  • Occupational health (OH) arrangements – Tideway has developed a strategy to manage workforce health and ensure consistency across the joint venture teams. It has employed a single occupational health provider to offer services to the MWCs (allowing worker health data to be collated in a single database). The OH arrangements include nurses and technicians at the three main drive sites and occupational hygienists who are procured through a specialist subcontractor.
The reports will be developed and updated as the research progresses and further reports will be added on topics including welfare and Tideway’s overall “Right Way” health, safety and wellbeing strategy. To find out more and to read the four reports published to date, go to http://tideway.lboro.ac.uk/

To meet the challenge that lies in benchmarking the “occupational health inspection sheet” scoring system, the three hygienists award consistent weighting to positive observations. Ball admits there is a degree of subjectivity to the approach, so it is important the whole team adopts the same process. To help improve consistency, he has explained his rationale for scoring to his colleagues and joined them on site visits to monitor their observations.

Ball began to trial the latest iteration of the scoring sheet on Tideway West in December and his plan is to use it alongside the HIFR for the first few months of this year to collect data. This, he says, will enable the hygiene team to get a “taste” for what is an acceptable score. It will also establish a strong baseline against which to track improvements.

“We have to have this transition and keep on collecting data using the HIFR,” he says. “I do like the data we are getting so I’d like to keep doing that alongside [the TR system] to give us a broader context and an overall score for the site.”

Ball explains that he will need to consult Tideway’s OH working group to discuss how the new system will be used in the future. Ideally, he would like it to replace the HIFR as the system Tideway uses to report against the safety and health performance index.

Then there is the potential for it to be adopted by upcoming projects such as the High Speed 2 rail link between London, Leeds and Manchester.

This is where Loughborough’s research comes in. As a relatively small resource covering such a large project, Jones sits on meetings in which she has access to HIFR outputs and the data gleaned from the new system once the hygiene team has collated it.  

Leap forward

“This is a big jump forward in occupational health terms,” she says. “It’ll be interesting to see how [the new system] works, how it gets embedded and who gets to do it. [With health], if you are not careful, it becomes the sole province of the experts.”

Ashwood and Ball are already looking at how the tool can be taken up by OSH professionals. One possibility is training Tideway’s health champions to use the tool. Ashwood says Tideway has yet to appoint the champions but the plan is to place one on each site to lead on the organisation’s OH and wellbeing programme.

“This is the challenge,” says Ashwood. “For many of our engineers, if you said, ‘We are going to use a breaker for two hours, what are the risks?’ I would hope most would say, ‘Noise, dust and vibration’. Would all of them have the skills to be able to assess that risk? No, but would they all know what the general principles of control are? Yes, and I think that’s where we need to do some upskilling so they can measure the exposures.”

As independent observers, the Loughborough researchers will speak to managers and supervisors as the development progresses, reviewing how their management of health risks compares with other sites. They will also ask whether they are receiving data from the HIFR tool and how this can help in the management of health risks.

It is also important to look at how exposure to health risks can be designed out.

Tideway-West-Dormay-Street-site-copyright-Tideway-West“We are asking [Tideway’s designers] what they’ve been able to do to design out health risks and where it has not been possible, what they’ve done to mitigate them,” says Jones. “We can then come at it from the other end and look at what happens on site. If there are health risks, we can then think ‘could they have been designed out?’ and look back to see if it was realistic and what would have had to happen to get a different outcome.”

The Tideway project is in its early stages. The boring machines have been delivered to the main site drives and are expected to begin work soon. As the project progresses and an increasing number of microsites open within the three tunnel sections, the research team will have a wealth of data to mine.

One notable challenge will be how the lessons can be applied to smaller projects where there are only a few construction workers. This is especially the case with the OH inspection sheet.

“What will be exciting to see is just how it goes down the supply chain,” says Jones. “Whether the contractors come away [from Tideway] and say, ‘I’ve learned this and I’m going to do this now somewhere else’. That’s got to be your goal: how you change the industry further down.”



Nic Warburton is acting editor, IOSH Magazine

 Nick Warburton was previously acting editor of IOSH Magazine. Before that he was editor of SHP and he has also worked on Local Authority Waste and Recycling and Environmental Health Practitioner

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