Alexander Dennis Enviro300

The Alexander Dennis Enviro300 (previously known as the TransBus Enviro300) is a light-weight full size single-deck bus built by Alexander Dennis (previously by its predecessor TransBus International) in the UK since 2001. The design was the first of the new Enviro range of buses from TransBus and also the first bus to be built as an integral bus by TransBus.

The Enviro300 was introduced in order to fill a gap in the manufacturer's product range. At the beginning the Cummins ISBe220 5.9 litre Euro III engine was provided as standard, but for Euro IV and V, the engine is the 6.7 litre ISBe with 225 hp for Euro IV and 225 or 250 hp for Euro V. There is a choice of 3 gearboxes: ZF 6HP504C (originally 5HP502C), Allison T280R and Voith D854.5 (originally DIWA854.3E).

It was developed to compete with the European-built heavy-weight single-decker buses sold in the UK, the most notable being Volvo. Many full-size (12m or more) single-decker buses are primarily designed for use on the continent and to carry a large number of standing passengers which is commonplace on the continent, but the Enviro300 is designed solely for the UK market where large numbers of standing passengers are not often carried. TransBus therefore believed that operators could make significant fuel savings by operating light-weight buses and produced a vehicle which is claimed to be lighter than its continental rivals but offer more seating capacity.

The Enviro300 had not sold as well as the manufacturer had hoped, though sales were not helped by the collapse of TransBus International in 2004. The majority of the original style Enviro300s sold to First Group are all operating within First Midland Red subsidiary, all but one are of 12m length. A small number of original style Enviro300 had been sold to Stagecoach Group and Cardiff Bus.

After few years since its launch, the chassis of the Enviro300 became available with East Lancs Esteem bodywork, with the first two for Courtney Coaches entered service in 2006. This is the first time the Enviro300 chassis being constructed with bodywork by another manufacturer.

In late 2007 Alexander Dennis introduced an all new 2nd generation version of Enviro300 which featured styling cues similar to the Enviro200 Dart and the Enviro400. The body is also available on MAN 18.240 and Volvo B7RLE chassis. The 2nd generation Enviro300 has been far more successful sales wise than its predecessor, including finding its way into some of Arriva and Stagecoach's operations, First has also purchased some new style vehicles for its other operating companies other than First Midland Red. For the Enviro300s with other chassis, Stagecoach placed the first order of 100 Enviro300-bodied MAN 18.240 as part of the 2007/8 order, 93 are standard 12m buses and the other 7 being 12.8m long, with the first one entered service in January 2008; further orders boosted the total number to over 350. In mid-2008 Ulsterbus ordered 45 Enviro300-bodied Volvo B7RLEs, which are the first to feature Volvo chassis since the introduction of this option, they are also built to a rural specification featuring unusual modifications such as narrower entrance doors, side wheelchair access door and 55 seatbelted seats in the form of 2+3 layout.

In January 2011, Stagecoach Group placed an order for 50 Enviro300s on the Scania K230UB chassis; further orders boosted the total number to 78. In April 2013 Reading Transport took delivery of 20 gas-powered Enviro E300SG buses based again on a Scania KUB chassis. These buses were jointly developed by Alexander Dennis and Scania, who have had a demonstrator on loan to other operators since March 2013.

In October 2012, Bus Timothy had purchased 14 Enviro300 single decker buses.