Zero-emission Enviro revolution

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It is an exciting time for the industry and Alexander Dennis as it launches a brand new zero-emission model into the market. Richard Sharman takes an in-depth look at the new Enviro400EV model

There have been many iterations of the Alexander Dennis (ADL) Enviro over the years since making its debut in 2001 in single-deck Enviro300 form and under the previous Transbus International brand. The last 20 years of Enviro production have seen some major innovations from ADL, with various drive trains, fuel types, and zero-emission offerings, including the introduction of the range nicknamed ‘MMC’ (Major Model Change) in 2014; an offering that was very much built alongside bus operators to develop the perfect bus from a driver’s, passenger’s and engineer’s perspective.

Now, a little under 10 years since the ‘MMC’ range was first introduced, ADL is once again on the charge to develop a completely new offering for the industry, but this time it is completely focused on making that offering one which is zero-emission and powered by electricity.


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An exciting time

It has been just under a year since Martin West made the move to ADL, after already gaining 27 years of coach and bus sector experience from roles of increasing responsibility including his most recent position as Sales Director (Bus and Coach, Power Solutions) at Scania. Speaking about taking up his new role as Group Commercial Director, Martin said: “Having enjoyed working in partnership with ADL for many years, I am very happy to now be a part of the global NFI team as we enhance and grow our offerings to the loyal customer base, as well as continuing to establish ADL as a trusted supplier and partner for many more operators, suppliers and authorities. The coming years are going to be the most intense and dynamic we have ever seen as our industry accelerates towards a net zero carbon future for public transport, and we are determined and well prepared to be leaders on that transformational journey.”

ADL President & Managing Director Paul Davies said about Martin’s appointment: “Our world is changing rapidly and we need to ensure that the structure and responsibilities of the team are aligned to the evolving market demands and business needs. Martin’s deep knowledge of all aspects of the bus and coach sector, gained with another world class company, will give ADL the additional bench strength needed to drive our business growth agenda domestically and across all of our international markets.”

The Enviro400EV features a new design language. RICHARD SHARMAN


“We announced that a new zero-emission buses would be joining our range in August, and since then we have been eager to share further details,” explained Martin at Euro Bus Expo late last year. “We are proudly able to share the first details of the new range, and although we do not have a fully built up model on the stand, we do have a mock up of an Enviro400EV chassis so that visitors to the stand can see where the Voith electric drive system will be located and what our new future-proof batteries will look like. We also offer an innovative and immersive experience and show a detailed video with 3D images of the new range.” he enthused.

“For me, it is very important that we are at the NEC for our customers and stakeholders, to meet and talk to them face to face and explain every detail about the new models. The new bus comes at a time when operators are looking to order against ZEBRA funding, so there is a window of opportunity for us to deliver the very latest technology to our customers.

“We expect that the first of the new models will start testing in July. We are at a stage where we our ramping up production of the new product, but we are also working with new suppliers in some areas, so its getting that initial supply chain going that is important so we can manage demand for the product in the first and second quarters of 2024 when many ZEBRA-funded models will be delivered.

“We will start off production building one a week, then two a week before building up to five a week at its peak. In October we already had existing ADL customers that were ordering the new product, and I think that is testament to the quality of the products that we deliver year in, year out.”

Ground-up new vehicle

“The Enviro400EV is a completely brand new concept. We started with a blank sheet of paper, and that is what has been interesting for me. In my previous role at another company, you were working with a bus design derived from the basis of a truck product which created compromises. At ADL the engineering, design, procurement and operations team have all worked together to develop a product with absolute focus on the passenger and operator of the bus for now and the future,” explained Martin.

“This has enabled us to design a bus with some of the battery packs in the floor of the vehicle, which is the ideal solution as we have been able to future-proof the design. As technology is moving so fast, we will now have the ability to upgrade the vehicles mid-life to whatever the latest technology is at the time, without having to make major changes to the bus. It is simply a case of fitting that latest technology into a battery pack, which is already quite slim.

“There is an eight-year warranty on the battery, with the opportunity to increase that to 12 years. When it is time for those batteries to be replaced, it will be a simple swap, out with the old technology and in with the new.

Stagecoach West will be the first to take delivery of the Enviro400EV, with 55 examples for its Oxford depot. ALEXANDER DENNIS

“We are thinking about the longevity of the bus, so we have chosen mechanical isolation of the batteries from the frame. They are not hard-mounted; with the flex and movement of the body the battery cells are protected as they are soft mounted. We have gone heavy duty with the under floor battery packs as you will always have a risk of road humps and kerb strikes, so the casing is made of a higher grade of steel to protect them. We have achieved the fine balance between the highest level of efficiency, strength and longevity.

“Away from the mechanics of the vehicle, we have designed the Enviro400EV to be a modal shifter. The flexibility we are known for will remain, so anything we can do to help operators attract more passengers, we will happily do.”

To this end, an attractive new design language, developed in house by one of the manufacturer’s industrial designers with input from students of Coventry University’s Automotive & Transport Design course, will give the new models kerb appeal and will highlight their zero-emission credentials, which ADL says will allow operators to make a bold statement that both underlines and showcases their clean transport investment.

Martin explained: “When designing the exterior we have looked at every piece of legislation due to come in for passenger carrying vehicles in the next few years to ensure the new model will be compliant when delivered and for many years to come.

“Everything has been built to ISO 26262 standard, which isn’t yet mandated in law, but we wanted to make sure the vehicle is going to be as safe as possible, and to that end it also meets the Level 5 London Bus Safety Standard, so every operators no matter where they operate will benefit from the highest safety standards. An interesting consequence of this is that the Enviro400EV is a standard 10.9m bus, but due to the rake and styling of the front of the vehicle to ensure it complies with safety standard means that it is actually now an 11.1m bus. The design also complies with the new R155/6 cyber security regulations that will come in during July 2024.

“A key point when it comes to the interior is that we plan to have a completely flat floor all the way to the rear five seats, something that is currently not possible with the BYD product. This and the fact that the batteries are located in the floor means we are able to increase the number of passengers carried to similar numbers to that of our diesel-powered vehicles, with 80 seated.

“The first three vehicles built will be for test and development, and after that initial production vehicles will be built. We expect serial production to commence in August, with the test and development vehicles being completed and certified during the late summer.

Driver comfort

Group Engineering Director Chris Gall joined ADL in August 2022, having come from Jaguar Land Rover where he was Chief Engineer for a number of products including the Defender. He had been in working in the car industry for 27 years, but wanted a new challenge where he could make a difference to the environment: “I want to make a difference in a proper decarbonisation industry. If I can leave a legacy that helped to get people out of cars and onto buses to help save the planet I will be a happy man,” he enthused.

“Since I joined I have been talking to many bus drivers that use our products to get their feedback. This is why we have done some work on the chassis dynamics to ensure the driver gets the same smooth ride the passengers will enjoy. It is very important to us that a driver is comfortable in the cab, as they could be there all day, so we provide a decent HVAC system, an ergonomic dashboard layout so that everything is within easy reach, a driver’s seat – with a seatbelt if required – that is comfortable, and then something we have really worked on is driver visibility. This is centred on ensuring the window pillars, security screen and windscreen are all perfectly placed so that drivers have the best opportunity to see what is on the road ahead and react to that accordingly.

“The new model will feature our next generation electrical architecture, which we call ADEPT, which uses a digital TFT screen rather than multiple dials, and this will be built into a brand new dash binnacle that will make use of both hard and soft keys. We don’t believe in removing all the buttons in favour of touchscreens, as that can be difficult to operate.

“The driver will also benefit from much more information and configurable screens on the digital display. There is a term I use which is to make everything ‘as common as possible, as different as necessary.’ One size certainly doesn’t fit all in the bus industry, and operators are investing a lot of money into these vehicles, so why shouldn’t they have a vehicle that has had a lot of thought put into it to give it a more premium feel, where everyone has been catered for, and importantly, which has been engineered well.

The rear wheels are driven independently. RICHARD SHARMAN

Next generation driveline

The Enviro400EV and international models such as the Enviro500EV for Hong Kong share key technologies including a next-generation electric driveline. The Voith Electrical Drive System (VEDS) has been developed specifically for the requirements of buses with an efficient permanent magnet traction motor that delivers substantial torque and power in a compact footprint, freeing up vehicle space for passengers and helping to improve ride quality through a low unsprung mass. The Enviro400EV uses the heavy-duty variant (VEDS HD), giving the double decker a 410kW peak power output as well as a high maximum running speed. Martin explained: “Some of our competitors are using medium-duty motors, but we believe that is not good for the longevity of the vehicles. That solution could be suitable for some applications, however the more rural routes call for a heavy-duty option.

“Having a heavy-duty motor means that you have driveability and durability on the road from day one, but importantly for an operator, it gives them the flexibility to move that vehicle around routes as required. We all know that in this industry you could build the perfect bus that suits one particular route, but in a few years things could change and that bus will need to be redeployed elsewhere on the network, so fitting the vehicle with a heavy-duty motor pays off throughout the life of the vehicle.”

The new future-proof ADL battery system is assembled by Impact Clean Power Technology to an ADL proprietary design that standardises packaging and interfaces to the vehicle. Dual sourcing is possible at pack, module and cell level, protecting customers and the vehicle design from adverse impacts of rapid development in battery technology, ensuring continuity of supply throughout vehicle life and allowing operators to benefit from technology advancements when the vehicle becomes due for a mid-life refresh without the need for extensive modifications.

ADL says particular attention has been paid to battery system reliability. The underfloor battery packs are mechanically isolated rather than directly bolted to the chassis, protecting them against external loads from twists and impacts that could cause premature failure, and feature a stainless-steel container and aluminium cooling plate to limit the risk of perforation or damage from road debris and infrastructure. String-level redundancy also ensures that the bus remains able to drive home in case of a single fault, reducing the likelihood of breakdowns.

In its initial application in the Enviro400EV, the ADL battery system will use heavy-duty, high-density prismatic nickel-manganese-cobalt (NMC) cells that are less susceptible to cold weather performance degradation and have a more gradual state-of-health decline. “With the Enviro400EV we have tried to address the issue operators have when moving the vehicle around different routes or depots,” said Martin. “We can use a three- or four-string battery, giving 354kWh or 472kWh options. The operator can change this mid-life or if the bus is redeployed, so a bus bought with 354kWh batteries can be upgraded to 472kWh to give it an increased range.”

Launch customer

Last month, ADL revealed that Stagecoach was the first operator to place an order for the Enviro400EV, with 55 examples heading for Stagecoach West’s Oxford depot later this year. Stagecoach is working with Oxfordshire County Council to decarbonise buses in and around Oxford thanks to funding from the UK Department for Transport as part of the Government’s Zero-Emission Bus Regional Areas (ZEBRA) scheme. Engineering Director Sam Greer explained: “We’re pleased to be continuing our commitment to move to a zero-emission UK bus fleet by becoming the first operator to make major investment in the new fleet of Enviro400EV buses to operate on our services in Oxford.

“We have a positive track record of working with Alexander Dennis to decarbonise our fleet across the country, including in Scotland where we will shortly be introducing the UK’s first all-electric bus cities. We look forward to working with Alexander Dennis and our partners in Oxfordshire to roll out these new electric buses as part of the important plans to improve air quality in the region.”

Welcoming the order, President & Managing Director Paul added: “We are delighted to have our long-standing partner Stagecoach as the launch customer for the next generation of battery-electric buses, partnering with us to lead the future success of our bus and coach industry. This investment keeps funding from the Government’s ZEBRA scheme in the country, improving the lives of passengers and residents as well as accelerating decarbonisation.”

ADL’s new ADEPT electrical architecture is seen in the dash binnacle of an Enviro400FCEV for Liverpool. RICHARD SHARMAN

International market

The international market has not been left out, with a three-axle Enviro500EV heading for the Asia Pacific region showing that the model continues to be a worldwide player. In March 2022, ADL announced that it was to build an initial 10 Enviro500EVs for Hong Kong operator Kowloon Motor Bus (KMB). The buses will be ADL’s first electric double deckers in the Asia Pacific region and will continue a the marque’s long-standing involvement in the Hong Kong bus market.

The 10 air-conditioned double deckers will be delivered in 2023 and, says ADL, will come with new and innovative features that will continue to raise the bar for efficiency, safety and comfort, as well as the capacity to carry up to 130 passengers, vital on Hong Kong’s busy bus services.

ADL has had a presence in Hong Kong for more than half a century, introducing features including air-conditioning to the market as well as low floor buses, before pioneering hybrid and now electric drivelines, in response to changing market demands. In all of those developments, ADL partnered with KMB, which operates on over 400 routes with a fleet of around 4,000 buses, mostly double-deck, including more than 2,500 diesel-powered Enviro500s.

A second order for the Enviro500EV came from Hong Kong’s Government-owned MTR Corporation, which provides Hong Kong’s Mass Transit Railway urban rail system, including a network of feeder bus services for which it operates a fleet of 169 buses, most of them supplied by ADL from its Enviro200, Enviro400 and Enviro500 ranges. Talking about the orders, ADL’s Managing Director for the Asia Pacific region Andy Boulton said: “With the next generation of electric bus technology, fully integrated by our own engineers, we are now in a position to deliver a zero-emission solution for Hong Kong’s world class transport system.”

Deliveries of both orders will commence this year, with the first example already build up in Hong Kong.

BYD partnership

The successful battery-electric BYD ADL Enviro200EV and Enviro400EV products built in partnership with BYD will continue to be offered in the UK, Ireland and New Zealand. “The BYD partnership has been fantastic for us,” Martin said, “We have over 1,500 BYD ADL buses on the road or on order now, so we will continue to also develop vehicles with them. We know what their next generation battery technology looks like. In addition, we don’t rule out building on Scania or Volvo chassis if the demand is there either.

ADL’s second-generation hydrogen bus, the Enviro400FCEV, will also continue to form an important part of the company’s zero-emission bus range, with the first examples already starting to be delivered to launch customer Liverpool City Region ready for launch later this year. The FCEV product shares technology and key driveline components with the upcoming new battery-electric models.

The end of diesel?

Talking about the current ADL diesel range and demand, Paul said: “We are heavily invested in the diesel product range and we believe that we have got a compelling, well known and reliable products with good residual values. Whilst we have a new EV range, we are still happy to build more of everything that the industry requires.

“This year we have seen many operators ordering more diesel-powered Enviro400, as if you think about it there was a level of underinvestment pre-Covid, UK-wide new bus registrations were on a downward trend and we have had three years of little growth, some of that because operators were waiting on confirmation of ScotZEB or ZEBRA funding, but I think the clock is fundamentally ticking on the average fleet age and they are going to have to invest, and whether it is diesel or electric, we are here to support them going forward.”

Alexander Dennis never fails to innovate when it comes to new challenges, and this is another example where it is showing that it is willing to invest in a completely new vehicle from the ground up in order to assist its customers in being as environmentally friendly as possible. The same also applied when Euro VI was introduced, and the ‘MMC’ models were launched.

With an expected operational range of up to 260 miles on a single charge with a four-string battery, a flat floor throughout, an improved cab and built to a whole host of safety standards, the Enviro400EV looks set to become a very familiar sight on the streets of the UK later this year and into 2024 as production ramps up.