Linienzugbeeinflussung - Malfunctions

Malfunctions

The LZB system has been quite safe and reliable; so much so that there have been no collisions on LZB equipped lines because of the failure of the LZB system. However, there have been some malfunctions that could have potentially resulted in accidents. They are:

• On June 29, 1991, after a disturbance, the train driver had the LZB system off and passed a stop signal with two trains in the tunnel at Jühnde on the Hanover-Würzburg high-speed line.
• On June 29, 2001, there was nearly a serious accident at the Oschatz crossover on the Leipzig-Dresden railway line. The crossover was set to diverging with a 100 km/h (62 mph) speed limit but the LZB system displayed a 180 km/h (112 mph) limit. The driver of ICE 1652 recognised the diverging signal and managed to slow down to 170 km/h (106 mph) before the crossing and the train did not derail. A software error in the LZB computer was suspected as the cause.
• A similar near-accident occurred on November 17, 2001 in Bienenbüttel on the Hamburg-Hanover rail line. In order to pass a failed freight train an ICE train crossed over to the opposite track going 185 km/h (115 mph) through a crossover that was rated at 80 km/h (50 mph). The suspected cause was the faulty execution of a change to the interlocking system where the crossover speed was increased from 60 to 80 km/h (37 to 50 mph). Without that speed restriction the LZB system did continue to show the 200 km/h (120 mph) pass-through line speed on the in-cab display - the train driver applied the brakes on recognising the line-side signal lights set to diverge and the train did not derail.
• On April 9, 2002 on the Hanover-Berlin high-speed rail line a fault in the LZB line centre computer brought four LZB controlled trains to a stop with two trains in each line direction being halted in the same signalling block (Teilblockmodus - divided block control). When the computer was rebooted it signalled 0 km/h (0 mph) to the trains in front and 160 km/h (99 mph) to the following trains. The drivers of the following trains did not proceed however - one driver saw the train in front of him and the other driver double-checked with the operations centre which had warned him prior to departure, so two possible collisions were averted.