German investigators are seeking to find out why safety rules did not prevent a high-speed magnetic train from powering up and rolling toward a maintenance vehicle still on the elevated test track. The resulting crash killed 23 people.

Alexander Retemeyer, a prosecutor speaking for investigators, said on Saturday they were focusing on what happened in the 32-kilometre track's control centre, where the required two employees were on duty.

"What we are looking into is why the train was given the go-ahead even though the maintenance vehicle was on the track," Ratemeyer said.

Friday's crash near Lathen in northwestern Germany was the first involving a train using magnetic levitation, or maglev, technology, in which the train rides on a magnetic field without touching rails. The lack of friction helps make possible speeds as high as 450 kilometres per hour.

The controllers, Ratemeyer said, were supposed to make sure the maintenance vehicle was off the track through several layers of checks. Only then were they to turn on the electricity enabling the train driver to start, he said.

Investigators examined the control room log book and discovered that the maintenance truck was where it was supposed to be.

It headed out at 8 am (0600 GMT) and was logged at a spot called point 120 on the rack at 9:53 am (0753 GMT) when the train started its high-speed run. Fifty-eight seconds later, the train hit the truck at 170 kilometres per hour.

The controllers had several ways to determine whether the vehicle was on the track: the log book, a check of its shed, and a GPS satellite navigational device on the vehicle, which showed it as a green dot on one of the computer systems but not the main security system showing the location of the train.

They were also supposed to get a radio call from other workers confirming that the vehicle was out of the way.

Further interviews will determine whether anyone had told it to return before the train came down the track, Retemeyer said. The two control centre employees have not been interviewed because they were in shock and undergoing care, he said.

More information was expected from injured survivors: Two workers on the service wagon as well as a train driver and a technician on the train.

"At this point, we believe the main reason is that the maintenance vehicle was not integrated into the train security system," said Retemeyer. "Safety for the maintenance vehicle is the responsibility of people, and so far we have not been able to determine any individual suspects because only now do we know the timeline of what happened."

Video cameras would not have alerted the controllers, since the crash occurred in a gap between camera coverage, he said.

The maintenance car was hit by the low nose of the speeding train and was flung upwards, ripping open the top of the first car of the train and strewing mangled seats, shards of glass and twisted metal parts below the 4-metre high track.

Transport Minister Wolfgang Tiefensee promised a "swift but thorough investigation."

"The question that we have to ask will be, was the security concept sufficient and was it followed step by step," he told reporters at the scene. "And then when we know what the reasons were, we will be able to draw conclusions."

Among the dead were two young people who had completed an apprenticeship at company working on the maglev train and were taking the ride as a reward, officials said. Officials said others included workers for Transrapid International, the company that makes the train, and one person from IABG, which operates the track. Transrapid International, a joint company of Siemens AG and ThyssenKrupp AG.

(China Daily 09/25/2006 page6)