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A low-floor bus is a bus or trolleybus that has no steps between the ground and the floor of the bus at one or more entrances, and low floor for part or all of the passenger cabin. A bus with a partial low floor may also be referred to as a low-entry bus or seldom a flat-floor bus in some locations.
Low floor refers to a bus deck that is accessible from the sidewalk with only a single step with a small height difference, caused solely by the difference between the bus deck and sidewalk. This is distinct from high-floor, a bus deck design that requires climbing one or more steps (now known as step entrance) to access the interior floor that is placed at a higher height. Being low-floor improves the accessibility of the bus for the public, particularly the elderly and disability, including those using and walkers. Almost all are rear-engine, rear-wheel-drive layout.
The main reason for choosing a low-entry configuration is to allow better placement for the powertrain and other technical equipment in the raised floor section, in addition to allowing a more comfortable ride on rough roads. Some manufacturers use the initials LF or L in their model designations for fully low-floor models (or in the case of German manufacturers, NF or N, based on the German word Niederflur, which means low floor), and in North America buses that are partially low-floor are often also designated LF. In some countries, LE, short for Low Entry, is used by some manufacturers in their model designations for low-entry buses.
Many low-floor buses, including the Irisbus Citelis (also in Skoda 24Tr trolleybus version), have the engine in a vertical cabinet at the rear of the bus. Van Hool have a series of "side-engine mid-drive" buses that puts the engine off to one side of the cabin longitudinally between the first and the second axle, to maximize usable cabin space. The same concept was also utilized by Volvo on their B9S articulated chassis.
For smaller buses, such as , the low-floor capability is achieved by placing the front wheels ahead of the entrance. One of the last types of buses to gain low-floor accessibility as standard was the minibus, where a similar front-wheel arrangement allows around 12 seats and a wheelchair space to be accommodated in very small low-floor minibuses, such as the Optare Alero and Hino Poncho. Accessibility was previously achieved in paratransit type applications, which use small vehicles with the fitment of special lifts. The inception of small low-floor buses has allowed the development of several accessible demand-responsive transport schemes using standard 'off-the-shelf' buses.
A disadvantage of the low floor is accommodating the bus's own wheels. With the low floor, the wheels protrude into the passenger cabin, and need to be contained in wheel pockets of waist height, and this occupies space which would otherwise be used for seating. To allow space for technical equipment, many low-floor buses have the seats mounted on podiums, making a small step up from the floor, while others are able to mount the seats directly to the floor, avoiding the step. Seating layout for a low-floor bus therefore requires careful design. Low floor configuration is also known to have poor side to side dead load distribution within the chassis due to the asymmetrical off-centre placement of driveline components - mainly engine and transmission. As a result, many of such buses require electronically controlled air suspension to compensate the lopsided configuration.
Low floors can be complemented by a hydraulics or pneumatic 'kneeling device', which can be used when the bus is not in motion, tilting it or lowering it at the front axle even further, often down to normal curb height. Depending on how close to the curb the bus is parked and wheelchair design, this can allow wheelchair users to board unaided. Though such technology has been available and in use on high-floor buses since the 1970s, it is of significant utility on low-floor vehicles only where it enables less-mobile passengers to board and leave the vehicle without help from others. Many vehicles are also equipped with wheel-chair lifts, or ramps which, when combined with a low floor, can provide a nearly level entry.
An implementation of the low floor design exists in Australia where custom coaches make a "hybrid" variant of its CB60 bodywork. These buses combine a smaller low floor area with a small underfloor bin for some luggage. Whilst these buses do not provide a full amount of luggage space, they can be used to house more luggage than what can be held inside the bus itself. Another drawback is the arrangement means the section of the bus that is at curb height is very short—consisting of enough space to house the wheelchair area and then rising up, to accommodate the luggage bin. These buses also lack the ability to have a center door.
Some transit agencies refused to order low-floor buses altogether, such as New Jersey Transit and MUNI owing to terrain conditions in the service area. DART still has a preference for high floor buses. Although New York City Transit runs some 40-foot low-floors, it originally refused to order low-floor buses, namely D60LFs from New Flyer, after the D60HF, a high floor model, was discontinued mid-delivery. However, they have demonstrated both the D60LF and NovaBus LFSA, the latter of which they have decided to order.
In order to keep the bus ticket prices low, the BMTC operates the majority of their services using Non-Airconditioned Semi-Low Floor (SLF) buses that have a floor height of 650mm as against the 400mm floor height of the true Low-Floor buses. These buses are from Ashok Leyland and Tata Motors, with future procurements planned to be from Eicher (VECV). These cheaper alternative to low-floor buses do not have kneeling or wheel-chair accessible ramps, but they have air suspension and use the same or better seats as those found in the Volvo buses. They also feature manual transmission as against automatic transmission
The term non-step bus may also refer to a high floor bus where the floor is flat in order to align with the high platforms in certain Bus Rapid Transit systems. Thereby, referring to it as a non-step high floor bus.
Low-floor buses are used on city bus networks in Metro Manila, Metro Cebu and Davao City, and on some provincial routes, and most Point-to-Point Bus services, although older coaches are still largely used for such services.
Buses used on the EDSA Carousel are usually equipped with 1-2 doors on the left side for boarding at the median stations, although not all units currently have them installed.
Low-floor buses often use upholstered coach-style seating in a 2-3, or 2-2 configuration, although plastic seats may be found in some buses.
In 2007, SBS Transit procured 1101 units of low-entry Scania K-series buses bodied by Gemilang Coachworks of Senai, Malaysia. Afterwards, all new city buses procured by SBS Transit, SMRT Buses and the Land Transport Authority are low-floor.
As of July 2025, all public buses in Singapore are low-floor.
London Buses was one of the earliest major users of low-floor buses, with the first low-floor single decker vehicles entering service in 1993 and the first low-floor double decker vehicles entering service in 1998. Following withdrawal of older, high-floor vehicles such as the AEC Routemaster, the bus fleet became fully accessible at the end of 2005, 10 years ahead of the national requirement. London was one of the first major cities in the world to have a fully accessible bus fleet.
Due to the bus deregulation of the public transport system in the UK, adoption of the higher cost low floor buses was usually in conjunction with some sort of grant or quality partnership with a local authority, as the profitability of many routes was not high enough to justify conversion based purely on increased revenue. It has been reported however that adoption of so-called Easy Access buses does have a positive effect of ridership and revenue levels.
Under the Transport Act 1985 the Disabled Persons Transport Advisory Committee (DPTAC) (or commonly DiPTAC) was established to provide independent consultation on accessibility issues. UK government In the same year, the first low floor bus specification was drafted by DPTAC. The Disability Discrimination Act 1995 provided for the completion of the Public Service Vehicles Accessibility Regulations 2000, Transport for you which specified that all new public service vehicles over 22 seats should be low floor from 31 December 2000, with smaller vehicles mandated from 1 January 2005. The 2000 regulations do not require retro-fitting of pre-existing vehicles or the enforced sale of non-compliant existing vehicles, allowing operators to retain a high floor vehicle until "the end of their economic life". In reality, as the prevalence of low floor buses spreads, combined with grants/incentives, it is likely that the prevalence of high floor vehicles in the national fleet will markedly reduce before all buses were de-registered by 27 October 2014. In the past, in times of reduced economic investment, it was not uncommon for service buses to be used for 15 to 20 years.
While some coaches have been produced with a small front low floor section at the driver's level, most coaches in the UK are being made accessible through the use of , with the 2005 Caetano Levante being one of the largest introductions. BBC
While another widely stated benefit of low floor buses is quicker boarding for able-bodied passengers due to the lack of steps, studies have found the opposite effect in the UK. This is apparently due to the prevailing system of operation where passengers enter and exit through one single front door. It has been suggested that the previous 1980s/90s high floor step entrance buses which featured a centre rail, encouraged a bi-directional flow of entering and exiting passengers simultaneously. The removal of the pole to allow wheelchair/buggy access created the situation where the quintessentially polite British bus passenger would wait for all passengers to alight before boarding, leading to an increase in dwell times.
In Saint Petersburg the transition to low-floor-only city bus services was completed only by 2021. Besides LiAZ-5292 and LiAZ-6213 and other full low-floor models that account for 85% of the city buses, there are also semi low-floor buses in service, with elevated floor in the rear end of the bus. The same applies to trolley buses that are mostly of low-floor design.
Other cities that use low-floor buses on the regular routes are Kazan, Sochi, Tyumen, Pskov and more. Most of these vehicles are domestically manufactured by LiAZ, GAZ, Kamaz and Volgabus.
Structural, which connect the large terminals of the regions to the center, or connect two large terminals of two regions passing through the center
Regional Articulation, which connect distant neighborhoods to the center without passing through large terminals, or connect two distant neighborhoods passing through important regions.
Locations/distributors, which connect neighborhoods to large terminals or stations. None of these lines pass through the city center.
Low-floor buses have become popular on the Structural and Regional Articulation lines, and have been a mandatory model to be purchased for these since 2015. Until then, exceptions for local lines with low-floor buses were rare, but this has been changing since 2019 and especially since 2023. In 2023, the city banned the purchase of new diesel buses. With the mandatory use of electric buses, new buses on local lines are also being made with low floors, as there is a very low or non-existent availability of high-floor electric buses.
The majority of standard and truncated vehicles were and are the Caio Millennium and Millennium BRT "toco" models, on Mercedes-Benz O500U, Scania K270 and K310, Volvo B7RLE and B290RLE and Volkswagen 17.240 and 17.260 chassis.
For articulated vehicles, Caio Mondego HA and Millennium BRT vehicles with Mercedes-Benz O500UA and O500UDA chassis were and are used.
The Biarticulates were made with Caio TopBus PB and Millennium BRT TopBus bodies on Volvo B360S and B9Salf chassis.
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