A “human error” may have caused the horrific accident involving a bus operated by Mumbai’s civic-run transport undertaking BEST, as the more than six-year-old vehicle appeared to be “mechanically sound”, officials said.
The nine-metre-long electric bus, manufactured by Olectra Greentech and operated by the Brihanmumbai Electric Supply and Transport (BEST) undertaking, rammed into pedestrians near Bhandup (West) suburban railway station on Monday night, leaving four people dead and 10 others injured.
Following the incident, the BEST General Manager directed the Assistant General Manager (Operations and Engineering) to conduct a probe and submit a report at the earliest. The Wadala Regional Transport Office (RTO) also inspected the bus involved in the tragedy.
“The bus appears to be mechanically sound. A human error might have caused the accident,” a senior transport undertaking official said on Tuesday, speaking on condition of anonymity.
At the time of the accident, the bus was being driven by Santosh Ramesh Sawant (52), who has been with BEST for the past 15 years, the official said.
According to a release issued by the BEST administration, police have arrested Sawant and registered a case against him for negligent driving.
Sources in BEST said that a few minutes before the crash, Sawant had driven the bus on Route 606 to Bhandup (West) station at an average speed of just 7 kmph. The bus was then parked near the station in a crowded area for about five minutes.
After taking a brief bio break, the driver returned to the steering wheel, and this is when the accident occurred, the sources said, adding that the exact cause of the crash was still under investigation.
The air-conditioned electric bus was part of a fleet of 25 midi buses that the BEST administration had transferred to the Vikhroli depot from Dharavi in the island city a few months ago. The move followed the scrapping of seven-metre-long mini buses that had been operating on the congested and narrow roads of Bhandup after completing their codal life, or estimated lifespan.
A Wadala RTO official said the bus, which is currently parked outside the Bhandup police chowki, was inspected and no adverse or mechanical fault was detected.
“The brakes were functioning properly and there was no issue with the starting system as well,” the official explained.
The official added that the RTO has sought inspection reports from BEST and Olectra on the bus’s condition, along with details of the driver’s licence from police.
Another RTO official, who inspected both the accident spot and the bus, told PTI that as per the preliminary investigation, the vehicle was taking a right turn from its starting point.
“The driver may have panicked while taking the turn, and in that situation he could have pressed the accelerator hard,” the RTO official stated, citing observations made during the inspection.
After the driver lost control of the bus, it hit a pole and the road median, he said.
RTO officials ruled out brake failure, noting that electric buses do not move if air pressure in the braking system is low.
According to officials, the Olectra-made midi bus is six years and four months old and was registered at the Tardeo RTO in August 2021.
A BEST official said the bus underwent a fitness test in August 2025, and the renewal certificate is valid until August 2027. The vehicle also has valid insurance.
As per Olectra officials, the bus was off-road between December 6 and December 24, during which its battery packs were replaced, and no mechanical defect was found.
This was the second such accident in Mumbai involving a wet-leased Olectra bus.
On the night of December 9, 2024, an electric bus hired by BEST on a wet lease basis from the private company ploughed into a crowd in the Kurla (West) area, killing nine people and injuring 40 others.
The civic-run undertaking provides transport services in Mumbai and adjoining areas, ferrying around 30 lakh passengers daily with a fleet of more than 2,700 buses.
