How Waitrose set its own standard

Located in the town of Bracknell in Berkshire, England, the John Lewis Partnership (JLP) head office and key distribution hub is more akin to a bustling campus than an austere industrial estate – not just because of the size and scope of the company itself, but more so because of the unique business model behind it.

With revenues of £9.75 billion (€11.6 billion) in 2015, JLP – which controls the John Lewis and Waitrose store chains – is the third largest privately owned company in the UK and employs some 92,000 people. Each of them is not just an employee, but also a shareholder in the business, with ownership managed through a trust that both reinvests profits back into the company and shares them among the staff in the form of an annual bonus. The result is an almost tangible buzz permeating the Bracknell site that is considered unique in modern British business.

In 2015, JLP paid out a bonus of 10 per cent of salary to everyone in the business – including the drivers of the 3,367 vehicles in the fleet, which breaks down into around 1,000 trailers, some 530 prime movers, 80 heavy rigid trucks, 237 light rigid trucks, plus nearly 1,000 3.5-tonne vans.

As such, the in-house transport fleet is more than a means to an end, says Simon Gray, JLP’s Vehicle Engineering Manager, pointing out that everyone in the business has a vested interest in keeping costs low and running the fleet as efficiently as possible. Procuring the right equipment to do so is one of Gray’s key responsibilities, and it doesn’t just extend to fuel efficiency alone.

According to Gray, his quest for achieving both environmental and financial benefits has recently led him to examine how aerodynamic drag may influence the performance of the JLP fleet, especially in a trailer context. While JLP had been specifying large radius capping on the lead corners for a long time, Gray admits there hasn’t been a systematic effort to understand aerodynamics until a government initiative – and the subsequent involvement of the Engineering Department at Cambridge University – triggered the company’s interest and led to the formation of a dedicated research team.

Gray says the team quickly recognised that although developments in the design of the cab-trailer interface as well as the rear section of the trailer were delivering improved efficiency, there was further research to be done on the area underneath the trailer. Starting off with testing scale models in a wind tunnel, the team quickly moved on to testing the flow around a trailer body in a water tank filled with silver particles that reflect laser light when captured by a high-speed camera.

Gray says Cambridge University’s particle image photography uncovered substantial added drag due to components such as battery boxes and landing legs – and also revealed the surprising amount of drag associated with a standard rear underrun protection bar. By optimising airflow around the trailer, the research team found a drag reduction of up to seven per cent was possible, which may result in an equivalent improvement in fuel economy.

The team found changes to the design of the trailer itself would result in a four per cent improvement, with a further three per cent attributable to airflow improvements on the truck, Gray summarises – enough to justify the construction of full sized prototypes and holding an extensive field test.

The test layout included longer and deeper side guards for both truck and trailer to smoothen longitudinal airflow and reduce the amount of air rolling under the vehicle. All components that proved to be impedimental to under-body airflow – such as the air tanks – were realigned to provide a ‘clear’ path for air streaming to the back, Gray adds. Another key adjustment was changing the rear underrun protection bars from square sections to round tubes, and switching to disc brakes to make the axles less prone to air turbulence.

Also part of the package was enclosing the walkway between the truck and trailer and lowering the prime mover via the air suspension, even though the degree of change was restricted due to access considerations. “A number of stores we supply have lots of elevation changes so we had to acknowledge that a lowered truck might not be able to go there. If you pumped up the airbags, the front bumper would drag, and if you lowered them, the landing legs would,” he explains. “But that didn’t keep us from testing the setting anyway.”

Gray adds, “When we first got the report we didn’t believe it. We thought they’d got their maths wrong, so I sent two team members out for two days doing some simulated testing over a distance of 250 miles (402km, ed.) per day and swapping drivers halfway to take out any variances due to human input. We then checked the telematics data and actually did get the same results as the lab.”

JLP’s research also showed that 35 per cent of trailer air drag comes from the area of low pressure in the vicinity of the back doors, he explains, a section that is crucial for overall productivity when loading. “As part of the project to improve aerodynamics, one of the key requirements was that no load volume was to be lost. We use standardised trolley cages across the group so we needed to make sure we could continue to use them.”

To still try and improve the critical rear section, Gray explains the test trailer floors were lowered as far as possible without mismatching the UK’s standard dock height, and the sidewalls were tapered in slightly by two to three inches (approximately 50-80mm). The last 500mm of wall insulation was removed to facilitate the reduction in overall width without affecting cage capacity and with little effect on temperature control. “The most noticeable change was the overall taper of the roof, which came down a total of 1.5m over the entire vehicle length, with the most pronounced change in the rearmost two metres,” Gray says.

In case it would come into contact with fixed objects such as awnings, the rear section was reinforced and compression bumpers were mounted to the substructure so any shocks could be absorbed through the trailer chassis rather than the high-tech body.
With the aerodynamics trial proving a success, Gray says additional measures have since been taken to apply the lessons learnt across the entire fleet. For example, JLP also operates a number of dual-deck (mezzanine deck, ed.) van trailers, which had the front roof profile contoured to deflect the air that passes over the truck.

Gray explains the reduction of frontal area is especially important given standard UK trailers are built to a height of 4.2m. As a major part of drag is proportionate to height, later generation equipment actually went to a height of four metres to save fuel, with a further 20cm reduction for the following batch. Naturally, front mounted refrigeration units still dictate the ultimate height of the trailer, but Gray says local refrigeration manufacturers have been involved in changing some of the front facing angles without sacrificing cooling capacity.

In the past, JLP had also experimented with underslung refrigeration units rather than the traditional front-mounted equipment, but they proved to be not as effective in controlling load temperatures during the warmer season. “It was a classic Catch-22 situation in which the aerodynamic side guards designed to keep air from going under the trailer prevented the refrigeration unit from being effective as a heat exchanger,” he explains, revealing the concept has since been dropped.
JLP’s standard trailer design spec has still changed dramatically as a result of the work done with Cambridge University, he says, with Gray & Adams – who played a key role during the trial phase – now delivering the majority of JLP equipment. “The new trailer design has become our ‘business as usual’ spec over the past two years and we continue to see benefits from it.”

Despite the time and money invested in arriving at this optimised design, the company has no intention of protecting the findings or keeping them to itself, though. “We’re happy for others to share it as our way of helping with the environment,” says Gray – pointing out that JLP’s average truck and trailer uses 40,000 litres of diesel each year. “As a business – and that includes us staff – we are proud to be a torch bearer for its business ethics and commitment to improving the environment. And it’s good for the bottom-line, too.”

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