Nine weeks they lost to the dead. Nine weeks they struggled to bring to being the store, with quiche bedecked. What cunning? What buildcraft? Thomas Lane tells the tale.

The battle of Waitrose

Credit: Max Schindler

Supermarkets pride themselves on their ability to put up their stores as quickly and cost-effectively as possible. It therefore came as a nasty surprise to Waitrose when its latest project turned out to be situated on top of 300 dead bodies.

And they weren't any old dead bodies, either. The site in Wallingford, Oxfordshire, contained an Anglo-Saxon burial ground, and each corpse was packed with information about how life was lived in the Dark Ages. This meant that they would have to be carefully exhumed, body by body; a long and painstaking process of retrieval and conservation. And while this was going on, little building work was going to be possible.

Andy Taylor, the head of innovation at Pearce Group, Waitrose's contractor on the £10.8m job, explains his predicament: "It knocked a massive hole in the development programme; nothing else could be done while the bodies were being removed," he says.

In the end, the design-and-build contractor lost nine weeks out of its 52-week programme. And, as Waitrose has a certain reputation to live up to, it wanted its store to open on the date it had originally planned: Christmas 2005 - and at the same price. So, it fell to Pearce to think of some way of clawing back 17% of its programme.

Pearce has a track record of efficient construction, but its speciality was putting up the same building type time and time again. Wallingford's Waitrose, on the other hand, was a one-off project in a tight town centre location. Pearce was rapidly running out of options and decided it needed outside help. The Construction Lean Improvement Programme run by the BRE came to the rescue.

The theory behind "lean" construction is elegant. It's all about driving timewasting out of construction processes, for example by arranging things so that tradespeople do not have to hang around waiting for materials to be delivered before they can start work. It also includes spending as little time and money as possible on processes that do not directly add to the finished product, such as putting up scaffolding. The Waitrose project was an ideal challenge for CLIP to get its teeth into as Pearce was already familiar with lean principles and its sites were already admirably efficient. "Most sites are well organised so you are not going to save great gobs of time," says Taylor, "so it's all about saving small bits of time."

The answer was to radically reconfigure the construction process so each specialist would get in earlier and out faster. Work done earlier would be problem free and the process would ensure other specialists on site at the same time wouldn't be in the way.

"The important principle is that one trade delivers to the next trade as quickly and efficiently as possible so the next trade hits the ground running," says Steve Ward.

CLIP proposed a small reconfiguration that would entail the subcontractors focusing on smaller areas of the site. Steve Ward, who began the project as head of innovation at Pearce but by the end had become so impressed by "lean" construction that he had joined CLIP, gives an example of how this works. At a hotel fit-out he had observed, the specialists were working on 20 rooms at once. It would take 10 days for the dryliners to put up the plasterboard. Once they had finished, another specialist would come in and tape and fill the joints, which would take seven days. The carpenters would then spend 10 days doing the door frames, making a total of 27 days before the painters could start. CLIP reduced the batch size from 20 rooms to four. Then each trade could be in and out in a day, making it four days for a room (including the painting). "If you apply that to a programme, it reduces it by 50%," says Ward.

Credit: Max Schindler

Credit: Max Schindler

It sounds great in theory but could a similar strategy, with each specialist concentrating on smaller areas than in the original construction programme, work at Wallingford? The first problem to surmount was convincing the specialists, which, according to Taylor, is much easier said than done. "It's anathema to this industry to have a situation where someone else benefits. It only works if it's worthwhile to you," he says. "The incentive is to prove you are an effective team and get more work on other projects."

The task for Ward was to visit the directors of all the specialists to convince them to adopt this method, explaining that they would have to see the follow-on trade as their main customer rather than Pearce. The idea behind this thinking is the specialist makes an effort to ensure the work is high quality, and it hands over to the next specialist bang on time.

He asked for their best people to work on the project. And he wanted to know the names of the foreman that would be running the job. When the directors balked, Ward explained that he needed to know because CLIP was going to train the foremen in planning techniques. "Nine out of 10 played ball so it was a worthwhile exercise," he says. "It was a bit of an effort at times, though."

One of the biggest adjustments for the foremen was having to attend a weekly specialists meeting. "For the implementation of ‘lean' on the ground you need the site foreman to get involved and come to the meetings every week," explains Tim Stringer, the account manager at Pearce responsible for looking after Waitrose.

At the meeting, each specialist would outline what they had achieved in the past week, and what they planned to achieve in the coming week. Any problems or clashes with other specialists could then be sorted out. According to Taylor, a sense of impending shame, as much as anything, made the specialists sort out what they needed to do, as they didn't want to confess they hadn't done it at the next meeting. For Stringer, this was crucial. "Having that meeting every week was key to making it work and they carried on right to the end of the project. It took a lot of discipline to do that as it gets busy towards the end, but it had to be kept going."

The building was conventional. It had a steel frame clad with precast wall panels. But the site would have looked strange to anyone used to conventional construction: the strategy of using small working areas meant that piling work was carried out at one end of the site, ground beams were installed in the middle and steelwork was going up at the other end. It worked during fit-out, too, with the result that Pearce clawed back its lost nine weeks and delivered the supermarket on time, and on budget. Not quite resurrecting the dead, but a minor miracle nonetheless.

Credit: Max Schindler

Credit: Max Schindler

The five principles of lean construction

1. Identify what adds value to the customer. From a lean perspective, value occurs when something changes in shape, form or function, resulting in the project progressing nearer to what the customer wants. Activity is not a measure of productivity if no value is being added to the project.

2. Work out the value stream. This means identifying all the steps needed to deliver the project from start to finish in detail. This helps identify what is adding value (maximise), what is necessary under current conditions but doesn’t add value (minimise), and what is waste which should be eliminated.

3. Ensure the value-adding steps flow seamlessly without any waste. This means ensuring workers have the right materials, plant and information, they are not kept waiting, their work area is no bigger than necessary, there is no rework and materials and plant are not moved around unnecessarily.

4. Get the supply chain to think about their role in the whole project rather than focusing on their one part of it. If specialists can be persuaded to see the next trade as their “customer”, the job will go faster with less rework and everyone will profit.

5. Aim for perfection. There is always room for improvement, and while today we do the job in the best way we know how there is no room for complacency – a better way always exists.

Waitrose: key points

  • Contractor Pearce Group lost nine weeks from its 52-week programme when it discovered 300 bodies under the Waitrose supermarket it was building
  • Waitrose didn’t want the store to open later than planned or pay more to speed up the construction programme
  • Pearce Group turned to Construction Lean Improvement Programme to find a way of clawing back lost time without it costing any extra
  • The construction programme was successfully reconfigured, enabling the supermarket to open on time and budget

Project team

client: Waitrose

architect: Michael Aukett Architects

main contractor: Pearce Group

structural engineers: Clarke Bond Structures

archaeological: John Samuels

demolition: Wring Group

groundworks: P Construction

piling: Cementation Foundations Skanska

steel frame: Pace Structures

pre-cast panels: Trent Concrete Cladding

roofing and cladding: Briggs Roofing & Cladding

terrazzo and flooring: Arvin & Sons

ceilings and partitions: Taylor Hart

mechanical services: SIAS Building Services

electrical services: T Clarke (Midlands)

shopfronts: Anaco Systems

refrigeration: Carter RRS

sprinklers: Compco Fire Systems