Sofia city prosecutors have asked national police to check the guardrails at the 36km mark of the Hemus motorway. The check follows a tip from the Road Safety Institute about how the barriers were fitted, the prosecutor's office said.
Police must find out how the guardrails were delivered and installed, whether they meet technical requirements, what checks were carried out and what payments were made. They will ask for the paperwork, and officials from the relevant institutions and companies will give statements.
Media reports say the barrier system was fitted with faults and that this puts road safety at risk.
The check must end within a month. Police will then report their findings to the Sofia city prosecutor's office, which will decide what to do next.