Alexander Dennis Enviro500 (3 Door)

For the 3-Door Concept Bus unveiled in 2016, see Alexander Dennis Enviro500 Concept Bus.

Alexander Dennis Enviro500 (3 Door)
Artist's Impression for ADL 3-Door Double Decker Bus (Photo: LTA)
Concept rendering of the ADL 3-Door Double Decker Bus (Photo: ADL)
Manufacturer Alexander Dennis Limited (ADL)
Bodywork Enviro500 MMC Facelift
Years in operation 2021‚Äď
Operators TBC
Technical Data
Length 12.5 metre
Engine TBC
Transmission TBC
Accessibility Low Floor & Wheelchair-accessible
Emission Standard Euro VI (SCR)

In April 2019, the Land Transport Authority (LTA) procured 50 units of the Alexander Dennis Enviro500 double-deck bus, configured with three doors and two staircases for smoother boarding and alighting.

These buses were procured under¬†Contract PT342 (Procurement of 3-Door Euro 6 Double Deck Diesel Buses) for ~S$34 million. In total, 100 three-door diesel buses were procured, with ST Engineering Land Systems fulfilling the other half of orders with its 50 MAN A95 (Euro 6) ‚Äď 3-Door¬†buses. Both bus types were initially expected to enter revenue service in 2020 (subject to delays).

This is the third batch of ADL Enviro500 buses supplied for Singapore’s public bus industry. Check out the main article: Alexander Dennis Enviro500 for more background information on the bus model.

Prior to the introduction of these buses, a one-off Alexander Dennis Enviro500 (3-Door) Concept Bus was commissioned by the LTA as a static display. It was first exhibited to the public in March 2016, and later received an upgraded new air-conditioning system in 2018 for permanent display at LTA’s Bedok Campus, with minor amendments to the bus cabin.

Enviro500 buses in Singapore:

These 50 new Alexander Dennis Enviro500 (3 Door) Buses would join the existing operational fleet of 216 Alexander Dennis Enviro500 public buses in Singapore, procured in 2 batches. They will also be the first Euro 6 Enviro500 buses in Singapore.

Design Features

According to Alexander Dennis Limited (ADL), the bus will feature a full-flat floor design along with three passenger doors and two staircases, one at the front and one at the rear of the vehicle, allowing commuters to move through the vehicle quickly and safely. It will also use the latest aluminium composite body technology and a host of new safety and energy-saving features.

Initial concept renderings reveal that the rearmost axle is used as the drive axle, which differs from the standard Enviro500 offering where the middle axle is the drive axle.  Significant redesigning work would also have been involved to relocate engine bay components to accommodate the right-hand-drive, third door and fully flat floor design.


Several concept renders were released by LTA and ADL shortly after the announcement of the tender result.


Contract PT342 (Procurement of 3-Door Euro 6 Double Deck Diesel Buses) was put up by the Land Transport Authority (LTA) on 15 May 2018 and awarded on 25 April 2019. Alexander Dennis and ST Engineering Land Systems would deliver 50 buses each, namely the Alexander Dennis Enviro500 and the MAN A95 (Euro 6).

Tender specifications for the three-door double-deck bus call for one entrance and two exit doors and the rearmost exit door must be behind the rear axle. In addition, the bus has two staircases and built in a low-floor design. Buses are also limited to a maximum length of 12.5 metres. These buses are also Euro 6 (or Euro VI)-compliant, representing the latest in emission standards which came into effect since 1 January 2018 for all new diesel vehicles registered in Singapore.

Existing LTA requirements for new buses include two wheelchair bays; a Passenger Information Display System (PIDS) comprising LED text displays, LCD display screens and interior speakers; Advanced Driver Assistance System and Anti-Fatigue system; high-definition CCTV cameras; and automatic passenger counters at entrance and exit doors of the bus.

Transition to clean energy bus fleet

The 100 three-door double-deck buses under Contract PT342 are the last pure-diesel buses to be procured for the Singapore public bus industry.

Authorities announced during the Committee of Supply Debate 2019 that Singapore would commit to a 100% clean energy bus fleet by 2040. This commitment was further reaffirmed in the Committee of Supply Debate 2020 held in March, where it was announced that only electric or hybrid buses would henceforth be procured in line with this clean energy goal.

Design Challenges

Prior to this tender, European bus manufacturers typically made fully-low-floor chassis targeted at their domestic left-hand-drive (LHD)-dominant market. As a result, drivetrain components are offset to the left of the chassis to accommodate a full-low-floor design and an optional third door at the rear. Given that the tender called for a right-hand-drive (RHD), full-low-floor diesel bus with a third door at the rear overhang, bus manufacturers faced the challenge of modifying existing designs to fulfil this (relatively) small batch of buses in the most economical way.

Alexander Dennis had previously delivered 3-door Enviro500 units in left-hand drive (LHD) specification to Transports publics de la région lausannoise (TL) and PostAuto in Switzerland; and to Berliner Verkehrsbetriebe (BVG) in Berlin, Germany. While Enviro500 buses typically feature Cummins engines, the BVG units are fitted with the Mercedes Benz OM936 engine from Daimler.

See Also:
External Links & References:

7 thoughts on “Alexander Dennis Enviro500 (3 Door)

    • 16 July 2020 at 2:43 AM

      The Last Unit were Delayed Registration Date till 2021 due to Covid-19 in 2020

  • 7 October 2019 at 11:45 PM

    I want 3-Door Buses Deployment on Service 88, 143, 179 & 190

  • 29 April 2019 at 4:15 AM

    Hopefully using the Euro6 Cummins L9 with 370hp 1600nm..As for ST bus can opt for the new Euro6 MAN 9000cc 360hp/1600nm

    • 16 December 2019 at 6:40 PM

      It’s actually supplied with a Daimler OM936LA.6


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