EXCLUSIVE: Inside ADL’s skunkworks

B&CB is first to get a look behind the scenes at ADL’s test and development site

The decision by Alexander Dennis to close the former Dennis chassis unit in Guildford in November 2020 may have brought to a close all ADL manufacturing in southern England, but the creation of its base in Farnborough promised some continuity.

The swanky offices and industrial unit sited on the perimeter of Farnborough Airport have been off limits for journalists since inception, with only a sketchy explanation of their function available as ADL commissioned the building.

Now, Bus & Coach Buyer has been granted exclusive access to ADL Farnborough, and been inside the ADL ‘skunkworks’ which trouble-shoots new designs as the company goes through one of the most dynamic periods in its history. Electrification of buses has created a raft of new challenges, especially as ADL under NFI ownership has developed its own range of vehicles alongside those with BYD-chassis.

Tucked behind the smart office frontage is one of the biggest development facilities in the UK, which runs a fleet of ‘mules’ to push every design element and modification to its limits. But ADL Farnborough is so much more than just a test facility, as we discovered.

Generational change

The Farnborough building was vacant for a number of years before ADL moved in. With Farnborough Airport on the site’s doorstep and the town’s association with aviation, there is no surprise a hangar-sized site was available.

ADL’s move to Farnborough was started in late spring 2022 and the site opened last June.

Stefan Baguette, Group Marketing Communications Manager, said: “When we decided to stop production in Guildford, it was never a question of closing down the entire south of England operations. We have so much expertise in engineering and we wanted to keep that.”



Some of the design and engineering work is done in Farnborough, with a slant more towards chassis engineering. But there is a significant number of body engineering specialists here too. Stefan said: “It used to be that Guildford did the chassis and Scarborough did coaches, but that is not the case any more. The work is spread across all of the sites. For example, the Enviro400EV is being led by someone in Larbert and the Enviro500 is being led by someone in Scarborough.”

The new facility is part of wider changes at ADL. Stefan notes the company has been using contract manufacturers in Leyland, MI Vehicle Integration for a long time. He explained that when the bottom fell out of the market in the pandemic, ADL was faced with substantial overcapacity. It was a very uncertain time in terms of understanding how demand would develop, so the decision was taken to cease some in-house manufacturing. “This gave us more flexibility,” Stefan said. “The pressure to do this was there even before the pandemic and our response to that is to be flexible. For example, in Scarborough, we converted the line from coach building to produce Enviro400s for Berlin.”

ADL still has its own engineering team, who give direct oversight on the ground every day at third-party manufacturers. Stefan added: “And if demand required it, we would do chassis manufacturing in Falkirk. But the market is still far behind where it was before the pandemic.

“We are going to retain this flexible model to build chassis and body at third party sites. Some of it will be owned by us, some of it won’t, but we will still have direct oversight.”

He describes the recent shifts at ADL as ‘generational changes’: “Inevitably when it came to closing the Guildford site, some people had really tough choices to make. But on the whole, there has really been a generational change. It’s been a generational change at the helm too, with Colin Robertson stepping back from his position as Chief Executive.”

Replacing Colin is Paul Davies, President & Managing Director. As the Farnborough site was opened last year, ADL introduced a fresh brand identity, unveiling a new logo. “This is the flagship office; it’s what we want our facilities to aspire to,” said Stefan. “It’s a modern space, fit for the future and fit for our requirements.”

Specially adapted for the manufacturer, the Farnborough facility is split into two broad sections: the workshop area and the open-plan office section that the engineering department is based in. Site lead, Rob Williams, said in total there are 110 staff based here, in the loosest sense of the term, with a hybrid work regime meaning many frequently work from home. Most here are long-serving employees, with Rob himself having worked for the company for 30-plus years.

This part of the building houses the technical authoring team, who put together manuals and guides for ADL’s vehicles and systems.

Technical assistance and product information is dispensed from the offices, with the AD24 aftermarket service’s phone centre based here. Rob said of this offering: “It was consciously modelled on NHS24, as it provides a full-time, all-encompassing solution where the customer knows they are going to be helped with whatever they need by professionally trained staff.”

The solution is available across its ranges and includes genuine parts provision to technical support, training, service centres and mobile technicians.

Stefan said: “We’ve always had the expertise. It’s about making sure that expertise becomes more easily accessible.”


“We train people to spot problems before a breakdown” – Geoff Range, AD24 Training Academy instructor

Heading from the offices, the tour takes us into the spacious workshop area, the layout of which can be altered to suit the work ADL has in. It is currently used for durability testing.

A section has been walled off with temporary partitions into an area that can be used for a number of purposes, including presentations or training. On B&CB’s visit, a team of technicians were learning about bus door diagnostics and repair.

AD24 Training Academy instructor, Geoff Range, is one of three trainers tasked with sharpening technicians’ knowledge. He said: “We want to ensure engineers are best trained to understand the vehicles. You don’t want a bus sitting around because the engineer doesn’t know how to fix it.

“Despite the growing amount of electronic equipment onboard modern PCVs, there are still mechanical parts that move hundreds of times a day. We train people to spot problems before a breakdown.”

He believes the next technological innovation that his training will be required on even more is electric drivelines. He said: “We try to pick up on new technology as soon as it comes through. And there is going to be a requirement for training on hydrogen vehicles.”

The training available covers a vast range of topics to ensure technicians can keep ADL and Plaxton vehicles in top condition. It involves classroom-based material and a practical element, often seeing the training team recreate common faults in systems for trainees to find and rectify. Courses Battery technology is also tested by ADL’s T&D team, with this set installed on an Enviro500 specified for California An Enviro200 converted to drive autonomously for the CAVForth project with Stagecoach is in for some work “We train people to spot problems before a breakdown” – AD24 Training Academy instructor, Geoff Range 26 FEATURE can be tailored to companies’ individual requirements.

Geoff said: “We do all sorts of training, some more basic and some more advanced. We have set courses we offer that give accredited IMI certification, but if it’s a one-off course we would just give an ADL certificate to show they have been through that course.”

ADL also provides courses for apprentices, often seeing applicants come in for one of its programmes during their third or fourth year of training. The duration and content of its programmes are flexible and can be tailored to operators’ needs.

The apprentices are not just 17- or 18-year-olds, Geoff notes; they can also be older. It’s not unheard of for a driver who shows promise to be initiated into the world of mechanics.

An Enviro200 converted to drive autonomously on the CAVForth project operated by Stagecoach

As well as training on-site, Geoff also trains in depots across not just the UK but overseas, having travelled as far afield as Hong Kong and Canada.

Geoff has extensive experience working in engineering. He started his career on the spanners with buses, before moving to BP where he worked in the R&D team to help build engines. He joined ADL around 20 years ago, starting out in technical support, until a job came up in the training department in 2010. “It’s been nice to pass the information I’ve built up over the years on to other people,” he said.

Over those years, he has seen significant advancement in bus and coach technology: “I think in general it’s got more technical. You now have to plug in a laptop to diagnose a problem; it’s a more analytical approach. But you do still need to understand the systems; it’s not just a case of plugging it in and saying: ‘It’s that bit there’.”


ADL’s Head of Chassis T&D, Peter Richardson, says the new facility is long overdue, and brings with it the room needed for sound development.

“This is certainly a massive improvement in the space we have available” – ADL’s Head of Chassis T&D, Peter Richardson

Formerly based at the Guildford site, Peter says Farnborough is a welcome relief: “Training and development had become squeezed,” he told us. “This is certainly a massive improvement in the space we have available.”

The Training and Development team of 29 aren’t all based at Farnborough; there are engineers at Skelmersdale and Scarborough, too. In the main, the team takes the first two or three production vehicles off the line to find out whether the CAD design and manufacturing between them achieve the design parameters and fine-tune systems or even individual components.

“In simple terms, we resolve issues which can’t be resolved by the field teams,” says Peter, who has 26 years’ engineering experience. “The reality is that you can do all the pre-production testing you want but customers can take the testing to the next level in the real world.”

It’s in the nature of fast-track modern design and production: “We always see the vehicles late; orders can be taken and we have to catch up. It’s not so much Ford as Formula One,” says Peter. In the main, the buses are heading down from Scarborough and Falkirk but sometimes they come back from China: “The decision you have to make is whether to take the bus to the test people or the people to the bus.”

Typically, buses which are either designed or modified for export need the Farnborough treatment. New Zealand Enviro200s with three axles are an example, says Peter: “The axle loadings are different. The handbrake is on the drive axle and the tag axle is heavier.”

Cast iron weights are still used to simulate loadings

To get the testing done, Farnborough has a highly-modified Dennis Sabre fire tender, the usual load of water tank and equipment replaced by a huge retarder. It’s this that the bus will tow around facilities such as Millbrook, the Sabre simulating and measuring huge hill climbs, and cutting in half the time it would take to conduct the testing without it.

The T&D facility carries stock of a variety of test equipment and components, together with a variety of mules drawn from production stock, none of which will ever go back into circulation. While we were there, we were shown aboard a ‘decker which was filled with cabling for electrics and test sensors, and the huge Proterra battery packs lashed to the floor.

There’s a poignant reminder of the Dennis factory outside; a large number of 500kg cast-iron weights which were actually cast back in the day when Dennis had its own foundry. Although ADL Farnborough’s quiet corners are occupied by Dennis museum pieces, these aren’t among them. They’re still used for the same thing; stand-ins for a full loading of people.

A highly modified Dennis Sabre is used by ADL for its test processes

Leave a Reply

Your email address will not be published. Required fields are marked *


This site uses some unobtrusive cookies to store information on your computer, these are in place to ensure that you receive the best possible experience when using the Bus & Coach Buyer website.