The Harmonised Guidelines and Space Standards for Barrier Free Built Environment Persons with Disability and elderly persons, which was released by the Ministry of Urban Development in 2016 has specified the features that accessible buses should possess.

Apart from having low floors, buses should have handrails and foot flights installed in addition to a hydraulic lift or a pull-out foldable ramp.

While the doors of the vehicle should be at least 1,200 mm wide, there should also be enough space inside for wheelchairs, such that they do not hinder passenger movement. Wheelchair stoppers and safety belts need to be installed. Alighting buzzers with visible push buttons are to be installed, and the information should be displayed in Braille and raised numbers for the benefit of the visually impaired. Information signs with the names of all stops should be easily readable.

Disability rights activists have been stressing on the need to focus on future procurement rather than retrofitting existing buses with inadequate equipment which might be dangerous.
In 2019, a demonstration and trial was held for disabled persons where a bus was retrofitted with an electric lift and a ramp. While participants in the trial had raised concerns about the height of the platform, a wheelchair user also toppled and fell when she tried to use the ramp.
 

Visually impaired persons who attempted to use the ramp also found it challenging.

“When we say buses should be accessible, this also means that it should be safe and comfortable for persons with invisible disabilities and senior citizens. All health disabilities should be taken into consideration,” said Smitha Sadasivam, member of the Disability Rights Alliance. She said that sensitivity of the conductors and drivers too was important.

“They need to wait not just until we have gotten onto the first step but till we are safely inside or seated. Buses should have earmarked seats right next to the entrance for persons with disabilities, so that they can be seated immediately as well,” she added.
Source: https://www.thehindu.com/news/cities/chennai/features-and-standards-essential-for-accessible-travel/article36216002.ece