Next generation Enviros revealed

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The new generation Enviro100EV and Enviro400EV. JONATHAN WELCH

Alexander Dennis has unveiled its next generation of electric buses. Jonathan Welch was at the launch to have a first look

We’ve known It was coming for a while, and on Wednesday 1 November operators were introduced to the latest generation of the Alexander Dennis (ADL) Enviro range. The new Enviro100EV small bus was presented alongside an Enviro400EV double-decker built on the manufacturer’s own electric chassis, as well as an Enviro500EV for KMB in Hong Kong. An Enviro200EV is expected to follow, and for now the new electric buses will sit alongside the BYD chassis offering in the same way that existing buses have been available on Scania chassis as well as Alexander Dennis’ own underpinnings.

Speaking at the launch, ADL Engineering Director Chris Gall said it was a pleasure and an honour to be able to lead the team behind the new buses and to present them to operators and the press. Engineered in house, Alexander Dennis says the new next generation range will offer more choice, more flexibility and more value thanks to industry-leading energy throughput and warranties. “We’ve done everything we can to ensure they meet customer needs using engineering principles,” Chris said, adding that ADL’s customers means operators, passengers and drivers, and praising the work of the design team, behind the new range.

The new Enviro generation also introduces a new design language that ADL says emphasises their zero-emission credentials and allows local authorities and bus operators to make a landmark statement of their investment in a cleaner fleet. Describing the new style at the launch, Chris said that they have been styled to reflect modern building trends, taking cues from modern cityscapes and buildings such as the Shard. The philosophy behind the new look is to show that operators have invested in something new and modern, whilst still retaining a style which is recognisably that of Alexander Dennis, and one which won’t date quickly. Looking at the double-decker, given that both previous generations of Enviro400 still sit well alongside newer models despite being launched in its original incarnation in 2005 (the ‘classic’ version remained in production until 2016, replaced by the ‘MMC’ which was launched in 2014).


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The driver

“We started with the driver,” Chris explained, taking guests aboard the Enviro400EV. “We recognised the fact that we’re in the middle of a driver shortage. Drivers spend seven or more hours per day in the cab, so we wanted to make their office space as good as possible. We feel our current cab is one of the best in the industry, so it was a case of evolution not revolution.”

Simple improvements include a new, more car-like steering wheel with a high quality feel, and two coat hooks. A climate control system from Grayson Thermal Systems has been designed to heat the cab from zero to up to 30 degrees in nine minutes, ensuring a pleasant working environment in the shortest possible time, helped by additional air vents on the dashboard. The new Grayson units also deliver a lower maintenance cost than previous units, Chris pointed out, delivering a benefit for operators too.

The dashboard binnacle has been redesigned to present sufficient but not excessive information to the driver in a clear format.

Outside the cab, a redesigned front geometry helps to give drivers better direct vision and protects vulnerable road users. As Chris explained, “we’re applying proven principles from the car industry to buses: provide improved visibility for the driver, modify the form of the front end to offer angles that deflect rather than impact, and reduce system stiffness to mitigate the risk of any impact that does occur.”

A deep windscreen, slim A-pillars and low cab side window back up this assertion, though the windscreen is not so low as to present an easy target for damage in minor accidents. ADL has also sought to give drivers good upward vision as well through the top of the windscreen, enabling a better all-round view as well as reducing the closed-in feel of a cab, especially on a double-decker.

Moving into the saloon, Chris commented that some bus designs felt like an engineering solution into which passengers were fitted, whereas the new generation Enviro range has very much been designed around its occupants first and foremost, with the technology fitted around them. Drawing on his 27 years in the car industry, Chris was keen to ensure that the bus had appeal to passengers and drivers alike.

The cab has been designed to give drivers the best possible working environment. ALEXANDER DENNIS


As well as the buses on display, ADL had a separate double-deck chassis available for viewing to better demonstrate the layout of the components. Chassis are constructed to ADL’s own design by existing chassis assembler MIVI, based in Leyland and now ADL’s only chassis supplier following the closure of its Guildford plant as a result of the pandemic.

Starting at the front, a single battery pack resides above the nearside front wheel, allowing the luggage rack above to still be at a low enough height for easy use. Beneath the stairs, two further battery packs can be found, whilst more are located within the floor structure behind the front axle, helping to balance the weight of the bus from front to rear and keeping it as low down as possible.

“We wanted to take as many batteries as possible away from the traction bay,” Chris explained, “to offer the best use of space and allow a low floor throughout.”

This adds to both practicality and the premium feel, he explained, by ensuring the layout could be maximised in the best interests of passenger comfort. Headroom at the rear appeared more than adequate, as did rear seat legroom, something which the first generation BYD ADL Enviro400EV drew criticism for.

The batteries are housed between the chassis rails, and mounted on resilient mounts to isolate them from chassis movement or vibration. They do not form part of the chassis structure, to protect them from premature failure, and have been designed to be easily removable and replaceable should that become necessary. ABS plastic covers are also fitted to minimise the ingress of road dirt and water into the areas housing the batteries.


The 11.1m double-decker promises a range of up to 260 miles with a 472kWh battery pack. For operators not needing to max out the power storage, a 354kWh option is fitted, which reduces the range but also the weight, allowing for a maximum of 97 passengers, which Chris points out brings the capacity in line with diesel models.

Of course, maximum range figures are very much route-dependant, and ADL will work with operators to determine the best package to suit individual routes or depots and use standard automotive industry software to work out what performance can be expected or achieved in any number of different conditions. As Chris pointed out, there’s often a difference between what operators want to know – the maximum range – and what then need to know – whether the bus will be capable of fulfilling their needs.

The batteries are provided by Impact Clean Power Technology, a Polish manufacturer which supplies batteries for the highly successful Solaris range of electric and hydrogen buses, and whose batteries ADL had already used on its hydrogen-powered Enviro400FCEV. Using NMC lithium-ion cells, the battery packs deliver a higher total energy throughput over the vehicle’s lifetime, including recharging and on-the-road regeneration, of up to 1.4GWh in the Enviro400EV, which ADL says will allow operators to meet operational requirements with the original set of batteries for longer. Those figures are based on a 472kWh battery pack and a battery life down to 70% of original capacity.

Mounting and connection points are standardised, meaning that upgrading to new battery technology in the future should be straightforward; Impact is already planning a future iteration of NMC batteries for Alexander Dennis that is expected to increase range even further.

Moving towards the rear, the bus is propelled by Voith’s Electrical Drive System, or VEDS, which has been specifically developed for the requirements of urban and interurban buses. The heavy-duty version is employed in the Enviro400EV for gradeability and maximum reliability, even at higher operating speeds; the bus can operate at a maximum speed of up to 60mph.

Chris added: “Impact and Voith both stood out with their innovation and attention to detail when we chose the technology partners for our next generation of buses. Our engineers’ work has extended beyond finding the best solutions for our customers as we have spent the time to design future-proof vehicle interfaces that also protect these critical components so that authorities and operators’ investment will stand the test of time.”

With battery life an ever-important consideration, ADL expects that, the Enviro400EV will be able to cover two consecutive seven-year contract terms on typical Transport for London routes without a battery change, or typical provincial routes for up to 20 years with just one mid-life change of batteries.

Old and new: the KMB Enviro500EV dwarfs the 1925 Dennis 4-ton bus. JONATHAN WELCH


Moving on to the all new Enviro100EV, it is an all-new bus which has been designed to step into the gap previously occupied by the shortest length diesel Enviro200, a length not available using the heavyweight BYD chassis found under the electric examples of the Enviro200 range. Said to be highly manoeuvrable at 8.5m long and 2.35m wide, the bus has been designed to still feel like a larger vehicle, and to offer a range of up to 285 miles on a single charge, which Alexander Dennis describes as class-leading. Although a shorter version is technically possible, ADL says it only plans to produce the bus in an 8.5m format. With options for 236kWh or 354kWh battery packs, the Enviro100EV uses the medium-duty version of VEDS more suited to its size, but as with the double-decker, it comes with a five-year warranty as standard plus an eight-year warranty on the batteries, with an extension of the latter to 12 years on what ADL says will be “a sensible commercial basis.”

The manufacturer explained that the configuration of the small bus had been chosen to give the best environment for passengers and drivers alike, including the choice of a ‘door forward’ layout to give a ‘big bus’ feel. Again, some batteries are housed in the chassis, supplemented by additional roof-mounted packs. Both buses also feature an electronic handbrake, first introduced to the ADL range on the Enviro400FCEV.

Whilst the double-decker chassis is built in the UK, the Enviro100EV is an integral vehicle, with the painted and glazed frame arriving from Alexander Dennis’ production partner’s facility in Zhuhai, where buses for the Australasian and Far Eastern market are produced. The company was keen to emphasise that this is solely for the Enviro100EV model, to enable it to meet the price point expectations for a vehicle in that segment. Once the frame arrives in the UK, shipped on a containerised flat rack, it will be constructed at an expanded production line in Scarborough, where large components such as axles will be attached along with wiring, driveline, seating and interior components.

Alexander Dennis noted that it has campaigned for more incentives to enable UK production, but says that no help has been forthcoming, and that the model would not be cost-effective if produced entirely in the UK at the current time, though points out that it has taken care to ensure that as much of the value and skill is retained in the UK as possible.

The Enviro400EV will be manufactured at Larbert, where the manufacturer has installed two new production lines. Alexander Dennis President & Managing Director Paul Davies commented: “We are introducing a split-build philosophy for our new ‘big small bus’ that is founded on the success of almost 4,200 buses we have assembled in Zhuhai over the last 15 years. Taking a more global view to our manufacturing strategy will allow us to increase our overall capacity and keep us competitive.”

Looking at the interior of both models on display, it was notable that ADL has chosen Lazzerini seats for both, rather than the Kiel-supplied SmartSeats, although these remain an option. Overall, the interiors appeared bright and well laid out; the spaciousness of the rear of the lower saloon on the Enviro400EV was particularly noteworthy.

Access to the upper deck via Alexander Dennis’ familiar ‘squarecase,’ with no angled steps, offers practicality and safety, and once upstairs passengers will find depth windows as well as a new panoramic upper front glass and optional skylights. Two wheelchair spaces have been included, to meet the latest ZEBRA and ScotZEB funding requirements.

A complete chassis was on display showing the layout of the batteries. Provision is made for a centre door. (The pale blue components are used to support and strengthen the chassis in transit prior to body construction). JONATHAN WELCH

Pace of change

Speaking about the launch, Paul said: “The pace of change in our industry is rapid. We are proud of the progress we’ve made with electric buses over the last seven years, and our wide range of low-emission technologies before that. Now it’s time for us to take the next step and take zero-emission buses to the next level.

“We’re giving authorities and operators more choice, more flexibility and more value with our next generation of battery-electric buses.”

Using route modelling and by factoring in finance options, power supply, maintenance costs and available grant funding, Alexander Dennis says it can offer its customers a 20-year total cost of ownership calculation, as well as recommend funding partners, including those ready to underwrite a full 20-year term, and infrastructure providers, or can work with customers’ existing partners.

The new generation buses will of course be fully supported by the manufacturer’s AD24 aftermarket division, whilst technical publications have been taken to the next level by introducing fully interactive manuals that link to technical support options and parts ordering in a single-login digital solution. Completing the support suite is AD Connect, a new, bus-dedicated telematics solution that gives operators the vehicle and fleet performance data they need as well as enhanced diagnostics, parts and repair information to further increase vehicle uptime.

Production of customer orders for both vehicle types has already begun, with deliveries expected in the first months of 2024. Homologation is ongoing, and some of those buses are expected to arrive ahead of its completion to allow driver and engineering training to begin ahead of a launch into service.

Wider view

The new generation range also includes the three-axle Enviro500EV double-decker for international markets, launched earlier this year in Hong Kong, and an international version of the Enviro100EV is under development, as is an autonomous Enviro100AEV and an open-top variant of the Enviro400EV.

The line-up for the UK and Ireland will be completed in 2025 with a new Enviro200EV single decker that will also be fully engineered and built in house, and offered as an alternative to the current BYD ADL product. Alexander Dennis says it will continue to sell and support electric buses built in partnership with BYD, of which over 1,500 examples are currently in service across the UK and Ireland. Unlike some other manufacturers, there are also no plans to set an end date for diesel production, which the firm says will continue for as long as there remains a demand.

Overall impressions of the new line-up are very positive; we look forward to testing the buses in real-world conditions in the new year. In the meantime, video footage of the launch event can be found on the CBW YouTube channel.

See our YouTube channel for more views of the new Enviro100, 400 and 500EV range

The next stage will see a new Enviro200 released, along with an open-top version of the Enviro400EV. ALEXANDER DENNIS
The interior of the Enviro100EV. JONATHAN WELCH