At least 29 people were killed when a bus travelling at high speed skidded off the accident-prone Yamuna Expressway in Agra and plunged into a drain, apparently after the driver had dozed off, early on Monday morning.

The accident has prompted road safety campaigners to call for efforts to address engineering concerns dogging the highways of the country.

An 18-month-old baby was among the victims. The bus was ferrying 40 passengers, and local authorities have admitted 11 injured to a medical college and hospital in Agra.

The bus of the Uttar Pradesh State Road Transport Corporation was allegedly speeding at 150kmph. The speed limit of the heavy vehicles on the expressway is 60kmph.

Conflicting reports trickled in from the ground. An injured passenger said a tyre of the bus had burst but he added that the driver was drunk and sleepy and lost control over the wheel. The driver was among those who were killed.

Another passenger said the driver had lost his way two hours before the accident. “Around 2pm, the driver took an unexpected turn and left the expressway. A passenger realised this after 10 minutes and shouted that the bus was not on the expressway. Then the driver returned on the expressway.”

Police said it appeared that the driver had fallen asleep. “The cause of the accident is a matter of investigation, but initially it seems that the driver of the bus fell asleep,” said Agra police superintendent Bablu Kumar.

The six-lane, 165km-long highway has been the site of several accidents. According to the National Highway Authority, it was the 95th accident on the Agra expressway in the past one year in which 92 people have died and 120 have suffered serious injuries.

According to RTI data accessed by NGO SaveLIFE Foundation, as many as 4,880 accidents have been reported on the highway between August 9, 2012, and January 31, 2018. More than 700 lives have been lost and over 7,488 people injured in these accidents, the NGO said.

“There’s an urgent need to improve enforcement on our highways. This is not a one-off incident. In 2017, over 9,000 people have lost their lives in preventable bus crashes,” SaveLIFE Foundation CEO Piyush Tewari said.

“The other urgent action required is on engineering issues. Most of our highways are missing crash barriers and other infrastructure measures that can prevent a crash from becoming fatal,” Tewari said.

The Yamuna Expressway Industrial Development Authority (YEIDA), which manages the expressway in western Uttar Pradesh, had identified three “black spots” on the stretch between Greater Noida and Agra where rumble strips have been created to keep drivers awake. The raised strips across a road or along its edge change the noise tyres make on the surface.

Ankur Kumar, one of the injured passengers, told reporters that the bus, called AC Janrath by the state transport department, had started from Lucknow at 9pm on Sunday for Anand Vihar in Delhi and was passing through Etmadpur in Agra when it fell into the drain, more than 60ft below the expressway at 4am.

“It ran for about 25 metres on the edge of the expressway before breaking the railing and falling into the drain. Most of the passengers were sleeping at that time. People in the neighbourhood somehow pulled us out of the bus. Some of them provided us first-aid as it took the police and other government officers 30 minutes to reach there and call ambulances,” Ankur added.

Chief minister Yogi Adityanath said he had formed a three-member inquiry committee headed by transport commissioner Dhiraj Sahu to conduct an inquiry into the accident and report within 24 hours. He has also announced a compensation of Rs 5 lakh to the relatives of each person killed and Rs 2.5 lakh to those of the injured.

• Additional reporting by PTI and Reuters