Sleeper bus fire safety concerns grow after 9 die in Delhi-Mahoba bus blaze: What retrofitting and overloading can change

Sleeper buses operating on highways are facing renewed scrutiny over passenger safety, overloading and unauthorised modifications after a Delhi-Mahoba AC sleeper bus caught fire on the Yamuna Expressway earlier this week, killing nine passengers.

Retrofitting firms told The Times of India that it is common for some bus operators to modify sleeper buses after obtaining fitness certificates and RTO clearances. These changes can increase passenger capacity but may also reduce aisle space and raise concerns over electrical and evacuation safety.

2x1 Sleeper Buses Converted To 2x2 Layout

According to retrofitters, sleeper buses approved with a 2x1 layout, with two berths on one side, one on the other and a central aisle, are sometimes modified into a 2x2 configuration.


The change can increase capacity from around 36 to 48 berths by adding 12 passengers. However, the additional berths reduce the available aisle space, while individual berths may also become narrower and shorter.

“Retrofitting is not a cosmetic modification. The moment you add AC units, electrical loads or alter the passenger compartment, you are changing the vehicle’s original safety configuration. Every such modification must be properly engineered, inspected and certified, otherwise a small electrical fault can rapidly become a major fire hazard,” a worker at a bus service shop in sector 44 said requesting anonymity.

“Retrofitting without proper technical checks can compromise the very safety systems designed to protect passengers in an emergency,” he said.

Questions Raised Over Fitness Testing

Former deputy commissioner (transport) Anil Chhikara said Rule 62 of the Central Motor Vehicles Rules, 1989, requires a new bus to have a fitness certificate valid for two years. Fitness testing is then required every two years until the vehicle is eight years old, after which testing is required annually.

“The VAHAN system allows online submission of fitness applications, fee payment and appointment/slot booking, but states that fitness remains a non-contactless service, requiring the vehicle to be taken to an RTO or fitness facility for verification and testing. For transport vehicles undergoing renewal, however, MoRTH has mandated fitness testing through private Automated Testing Stations (ATS), eliminating the need for an RTO visit or inspection by a regional inspector,” said Chhikara.

Chhikara alleged that in practice, some renewal checks do not involve a genuine physical inspection, with vehicle owners sometimes being allowed to upload photographs instead. “In fact, 99% of the buses that have been involved in fire incidents have not been genuinely tested even once,” he said.

He also called for greater scrutiny of private ATS operators.

Electrical Modifications Raise Fire Concerns

Chhikara said several sleeper buses involved in recent fires were BS-VI vehicles and pointed to their extensive wiring systems as an area requiring investigation. He said modifications to alternators, batteries and wiring can be carried out after the bus chassis has been built, potentially increasing the electrical load.

“Local retrofitters may switch the bus’s original alternator with another one, which is not specifically designed for it,” Chhikara said. “During my stint at a private auto company a few decades ago, I learned about power take-off (PTO) units, which are mechanical gearboxes that transfer engine power to auxiliary equipment such as hydraulic pumps. The AC systems of these vehicles should have had matching specifications, but operators change the wiring to draw more load from the ACs, which is illegal and fraught with dangers.”

Chhikara also alleged that some retrofitters use household-type wiring that may not be designed to handle the electrical loads inside a bus. Additional equipment, such as speakers, can put further pressure on the system.

“Govt has set standards for buses, but standards for electrical load have not been designed so far. This is why the local coach builders can tweak the wiring of the vehicles so much. They are totally unaware of the specific design they need too,” he said.

Illegal Retrofitting Not Permitted

Under Section 52 of the Motor Vehicles Act and Rule 112 of the Central Motor Vehicle Rules, vehicle alterations, including changes to body structure, are required to comply with prescribed standards and be carried out by authorised entities. Unauthorised modifications are not permitted.

Blocked Exits And Missing Safety Equipment

Industry sources also raised concerns about emergency exits being obstructed by luggage. In some buses, goods and luggage are reportedly placed near exits, potentially making evacuation more difficult during an emergency. Other reported concerns include inadequate fire extinguishers and missing emergency window-breaking hammers.

Safety experts said blocked exits, narrow aisles and inadequate emergency equipment can make evacuation particularly difficult during a fire, when smoke and panic can quickly restrict visibility and movement.

Bus Manufacturers And Body Builders Under Scrutiny

Shyam Lal Gola, general secretary of the Delhi Interstate Bus Operators Association, said responsibility for safety should not be limited to bus operators. He said manufacturers, bus-body builders and companies involved in installing air-conditioning systems should also be examined to determine whether their work contributed to fire risks.

[With TOI inputs]