Government corruption and deteriorating roads caused a fiery multiple car and truck crash in Nigeria that killed at least 18 people in 2010, a coroner said Wednesday, highlighting major challenges facing Africa’s most populous nation.

Police set up an illegal checkpoint August 2010 along a major expressway in Lagos, using tires to funnel traffic down to one lane as officers demanded bribes from motorists, witnesses said. The driver of a speeding truck carrying sugar for the nation’s largest industrial company tried to stop, but the vehicle’s bad brakes failed and the truck slammed into waiting traffic, witnesses and officials said.

Those details, long denied by authorities, came out Wednesday when a coroner investigating the deaths ruled against Nigeria’s federal police and the Dangote Group, owned by billionaire Aliko Dangote.

However, lawyers say this is merely a first step toward winning justice for victims of the crash in Africa’s most populous nation, where corruption and incompetence strangle government agencies responsible for protecting citizens.

“The culture of lying, misrepresenting facts and denying responsibility is something we see over and over again,’’ said Joseph Otteh, the executive director of Access to Justice, which took part in the inquest. “We have these deep problems in Nigeria, but the thing is we have a process to reach down to the truth.’’

The coroner’s inquest focused on only one of the horrific multiple car crashes that happen almost daily in Nigeria, the third worst country for traffic fatalities behind China and India, the World Health Organization has said. Drivers travel at high speed and overtake slower vehicles, leading to such head-on collisions. Main cities are linked by pitted, two-lane roads crammed with passenger buses, trucks laden with goods and rickety private vehicles.