Fully-Low-Floor vs Low-Entry buses – A minor detail that makes a huge difference

The type of bus a city chooses affects how many people it can move, how easily they can board, and the experience they have onboard. India has traditionally favored high-floor buses, which still make up the majority of the fleet in several city transport units today.

In recent years, however, low-floor buses have gained popularity. With the rollout of EV policies, cities are moving away from high-floor buses, which are inconvenient to board – especially for women with strollers and people with disabilities.

However, “low-floor” is a broad term that can be further categorized into fully low-floor and low-entry buses. To the average person, they may seem identical, but there are key differences between the two.

Similarities

Both types of buses offer the same ease of boarding and alighting through the first two doors – one near the driver and the other in the middle of the bus. The absence of steps makes getting in and getting out quite a breeze.

The entrance to the bus often aligns with the footpath, further reducing the height to board it. People with reduced mobility or with luggage can easily hop onto one.

The middle section in both the models can accommodate standing passengers, strollers or wheelchairs. Some transport agencies install foldable seats that can be pulled down for sitting.

Large doors allow passengers to easily get in and get out, and the low floor nature allows agencies to meet the accessibility targets, and deploy them in large numbers.

Differences

Significant differences emerge in the rear section. Low-entry buses have a raised seating area, allowing for more passenger seats compared to fully low-floor buses.

This inclination at the rear is to house the engine underneath the seats as seen in the image below.

Here’s what the rear section typically looks like – a row of seats with decreasing headroom as you move further back.

Access to the raised rear section requires steps, which begin in the middle section of the bus. The issue with stairs is that they can cause people to trip and fall, making it one of the most common complaints.

Another problem is that as the bus gets crowded, passengers tend to cluster in the middle section rather than spreading out toward the back. This is due to the reluctance to stand on a steep platform and the lack of headroom in the rear.

A fully low-floor bus, as the name suggests, remains completely flat throughout, all the way to the back. The engine is typically placed at one of the bus’s corners, as shown below, and is positioned vertically rather than horizontally.

This bus design prioritizes space for standing passengers over seating, as it features fewer seats overall. The advantage of the fully-flat design is that the third door at the back can also be low-floor, unlike in low-entry buses, as shown below.

Indian transport agencies typically opt for low-entry buses. I have personally used Volvo buses with BMTC (Bengaluru Metropolitan Transport Corporation), and to my knowledge, there are no agencies in India that have adopted fully low-floor buses.

When to choose what?

Fully low-floor buses are mechanically more complex than the commonly used low-entry buses. They are also more expensive to buy and maintain, with some costly components positioned close to the ground.

However, they are a great addition on routes for maximum accessibility and fast boarding/alighting. Completely step-free access throughout the bus, improving mobility for all passengers, and sections of the bus are equally crowded.

Low-entry are value for money and allows greater seating capacity. On long distance routes within a city, it makes more sense to deploy these. They also have a better ride stability on wide traffic-free roads due to a more conventional chassis layout.

How’s it in EV buses?

Since electric buses (EV buses) don’t have bulky internal combustion engines, they offer better passenger ergonomics overall and have addressed this issue to some extent. While most EV buses are fully low-floor, some are designed as low-entry buses.

The design of the rear section depends on where the batteries are located. They can be placed under the rear seats, on the roof, or at the back of the bus.

Here’s a fully-low-floor model from Isuzu that places battery on the roof of the buses freeing up the space in the rear. To help matters further, it also uses “in-axle motors”, where a motor is built into each side of the rear axle.

If the batteries are stored under the rear seats, it raises the rear section like a low-entry bus, though typically to a lesser extent. However, there are various buses that combine both designs, depending on the range required.

Here’s a model from Switch Mobility EV bus that is low-entry with a raised rear section. This particular model has already been deployed in a few cities in India.

Here’s a bus design where the batteries are located at the back. This allows the floor to remain low throughout most of the vehicle, while concentrating the battery pack in a compact area at the rear.

Ultimately, the choice between the two depends on your specific priorities— whether it’s maximizing accessibility, optimizing seating capacity, reducing costs, or balancing performance and maintenance needs.