Alexander Dennis Enviro400

The Alexander Dennis Enviro400 is a 2-axle double-decker bus built by Alexander Dennis from late 2005. It is designed as the replacement of the Alexander ALX400 and the Plaxton President body.

The Enviro400 was designed by TransBus International until its collapse and reformation as Alexander Dennis. The Enviro400, like the other products in the Enviro range, is a complete bus, but the body is also available on the Volvo B7TL/B9TL and Scania N230UD chassis for sale in the UK market. The Enviro400 chassis can also be built with body by other manufacturers.

Internal layout
The Enviro400 features an innovative seating layout that maximizes use of seating space on the lower deck by placing 2 forward-facing moulded seats onto the front nearside wheelarch box with a small luggage shelf on the rear-half, and also a single forward-facing moulded seat on the front off-side wheelarch hub between the driver's partition and the staircase.

Powertrain
The engine is a six-cylinder Cummins EEV driving through a Voith or ZF automatic transmission. An electric hybrid version is available.

United Kingdom
London operator Metroline was the first company to order the Enviro400, with the first of 28 entering service in January 2006. One dual door demonstrator, named "Spirit of London", was delivered to Stagecoach London to replace the Dennis Trident destroyed during 7 July 2005 London bombings and a single door demonstrator was delivered to the then Travel West Midlands (now National Express West Midlands) for evaluation. Both prototypes were exhibited at "Coach & Bus Live 2005" in the National Exhibition Centre in Birmingham, UK and then entered service in January 2006. Metroline, National Express West Midlands and the Stagecoach Group were large customers of the Dennis Trident.

The Enviro400 had sold well in London with a number of operators, such as Travel London (now known as Abellio London) and London General (which received the first Euro IV-engined Enviro400 in May 2006), operating these buses. It is also popular with Stagecoach, who placed its first order of 130 low-height models in February 2006, later followed by another 389 buses with Euro IV/V engine. Arriva also received Enviro400s for their UK operations, Arriva Merseyside relaunched their Wirral - Liverpool 'Cross River' services with a batch of 23 in January 2009, and a further batch of 12 were introduced to Arriva Merseyside's cross-Liverpool service 60 linking Bootle with Aigburth in September 2009.

On 13 October 2006, Solent Blue Line received a Volvo B7TL/Enviro400 meeting the Euro III emission standard, with the interior in Wilts & Dorset livery. This remains a one-off as all subsequent Enviro400s on Volvo chassis were built on the B9TL chassis. An Arriva demonstrator was shown at Euro Bus Expo in 2006 to the latter standard.

In the UK, East Yorkshire Motor Services took delivery of 5 Enviro400-bodied Volvo B9TL in December 2007, which entered service in January 2008. London General also received 3 Enviro400-bodied Volvo B9TLs in October 2008, which are being evaluated against integral Enviro400s and Wright Eclipse Gemini-bodied Volvo B7TL/B9TLs that are extensively featured in Go-Ahead's London Central/General fleets.

Stagecoach announced on 28 February 2007 that it had ordered 25 Enviro400s with Scania N230UD chassis, which were subsequently delivered in early 2008. These were followed by another 56 for delivery in 2009, 100 for 2009/10, 100 for 2010/11 and another 91 for 2011/12. 57 are planned for delivery in 2012/13. Oxford Bus Company and Wilts & Dorset also received some examples.

There is also a hybrid version af the Enviro 400 that has been bought by a number of operators including East Yorkshire Motor Services, Reading Buses, Lothian and First Glasgow.

In 2008, one Enviro400 was built for the 2008 Summer Olympics and 2008 Paralympic Games as a Handover Bus.

In 2012, Go-Ahead's Southern Vectis business submitted an order for 20 Enviro400 double-deckers for School Contracts on the Isle of Wight. These were delivered during late-December 2012 and early-January 2013 and entered service on a wide variety of school services on the island from 7 January 2013. Southern Vectis then proceeded to order another 16 Enviro 400 Double Decker Buses to be used on Public Routes, mostly route 9, with the first 6 going to Oxford for a few months. 10 of these buses have been delivered and on 3 January 2014, commenced operating.

Ireland
Irish state run operator Dublin Bus was the first bus operator to order the Volvo B9TL-based Enviro400, it ordered 50 with the first of these entered service on 14 August 2007, later followed by another 50.

Hong Kong
In 2009, Kowloon Motor Bus and Citybus of Hong Kong received two (one for each operator) air-conditioned Enviro400 for evaluation, both of them entered service in February 2010. Citybus introduced one more in July 2010.

In November 2010, Alexander Dennis had confirmed an extra order of 38 Enviro400s from Citybus at press conference of Euro Bus Expo 2010 held in Birmingham, UK, these buses entered service in 2011. Further orders of 20 Enviro400s had been placed and the buses started to enter service in 2013.

MTR Corporation also ordered 9 Enviro400s for MTR Bus service, these buses entered service in 2012.

Kowloon Motor Bus received a further 50 Enviro400s between 2012 and 2013.

America and Canada
On 11 November 2010, Alexander Dennis announced they received an order for 10 Enviro400s from Coach USA subsidiary Twin America, in New York. The Enviro400 is only available in North America as an open-top tour bus and was introduced in 2011. E Noa Tours of Honolulu received three in early 2012.

Some examples had also been sold to Canadian operators.

Nepal
Kathmandu had also bought 18 Enviro400s for their service to complement with their latest Ashok Leyland Titan (fitted with Enviro500 bodies).