"Since it uses voice recording, the system could be applied to people at the controls of any means of transport," said the official at the Engineering and Safety Department of the Land, Infrastructure and Transportation Ministry.

"On average, 80 percent of traffic accidents stem from human error ... if we can reduce human error, the number of accidents will also decrease," he said.

The system was developed by the publicly-funded Electronic Navigation Research Institute.

It can tell how tired or stressed the speaker is by detecting irregularities in frequency modulation and analysing other factors, the official said.

The ministry is considering introducing the system under a four-year project possibly starting in 2004, he said.

In February, the nation was shocked to discover the driver of a Shinkansen bullet train had fallen asleep on the job while travelling at 270 kilometres (169 miles) per hour with 800 passengers on board.

The train ran for about 26 kilometres in western Japan. No one was injured in the incident as an auto control system onboard stopped the train at a station.

The 33-year-old driver was later diagnosed as having a sleeping disorder.

SPACE.WIRE