Human error and brake failure are the likeliest cause of yesterday’s bus crash that claimed 56 lives.

Four out of every five crashes in Kenya are caused by reckless driving, according to the National Transport and Safety Authority.

This includes freewheeling in an attempt to save on fuel and breaching speed limits.

In either circumstance, drivers are likely to lose control of the vehicle, as could have been the case in the crash.

It was easily the worst traffic accident in recent years. NTSA has 4am as the time travellers are least likely to die with 8pm as the worst.

A survivor said the bus could have been speeding when the dawn accident occurred, raising renewed concerns about the structural strength of locally-assembled passenger vehicles.

An assessment of the wreckage suggests the shell was ripped apart, with the roof separated from the body.

Traffic officers involved in the rescue efforts said the driver lost control of the vehicle that was headed to Kakamega from Nairobi.

Investigations will indicate whether the bus was in good condition to ferry passengers, with the police claiming it had not been permitted for night travel.

Joel Mokola, an automotive engineer, said brake failure and human error were intertwined and urged drivers to be keen to rectify mechanical faults before they ended up in crashes. He added that the braking system for heavy vehicles such as buses use compressed air rather than fluid, which is common with smaller cars.

“There are several reasons that could lead to failure of the braking system. Loss of pressure along the system linked to leaks is the most common cause of failure. Worn out brake pads would also mean a driver cannot regulate the speed, thus the inability to control the vehicle,” he said.