B2/​1998R Haz­ardous sit­u­a­tion in train traf­fic at Ker­ava, on De­cem­ber 7, 1998

29.10.1999

On Monday, December 7, 1998, in the southern end of Kerava railway yard, a hazardous situation arose when a passenger train travelling from Helsinki via Kouvola and Pieksämäki to Iisalmi ran into a turnout at too high a speed. The trainset consisted of two Sr1 electric locomotives and ten passenger coaches carrying a total of about 300 passengers. No personal injury or material damage occurred.

The train passed Korso station at a speed of 120 km/h. After Korso in a curve there is the distant signal of the arrival main signal at Savio. The distant signal displayed two yellow lights, i.e. a “wait stop” aspect, implying that the next main signal displays a “stop” aspect, which in fact made the driver brake quite intensely all the way to emergency braking. Before the stopping of the train the aspect in the main signal changed to a “proceed” aspect, and then the driver started to accelerate. However there was something wrong with the power regulation in the locomotives, and as a result the power fully switched on only after some attempts.

The departure main signal at Savio displayed a “proceed” aspect and the distant signal below displayed a “wait sn 35” aspect. According to his recollection, the engine driver perceived the aspect of the distant signal. The driver was running at a speed of 80 km/h towards Kerava up to the arrival main signal at Kerava and the distant signal of the departure main signal there below. The main signal displayed a “proceed sn35” aspect, as expected according to the distant signal aspect. The distant signal displayed a “wait sn 110” signal with a yellow “11” figure aspect below the yellow and green lights. According to the main signal aspect, there were turnouts allowing a maximum speed of 35 km/h on the track after the signal in the southern end of Kerava railway yard. The distant signal aspect indicated that succeeding the next main signal, i.e. on the track in the northern end of the railway yard, there were turnouts where the maximum permissible speed is 110 km/h.

Normally the train would pass Kerava and run straight forward on track 2; however the night preceding the incident two fuses of the melting resistors of a turnout in the northern end of the railway yard, had burnt. As a result the turnout had stuck, and all trains heading northwards had to be run via track 3. The drivers are informed of any exceptional routes by signal aspect indications.

The driver ran to the sn 35 turnout at a speed of 77 km/h. The direct reason for the speeding was a misinterpretation of the signal aspect, which was mainly due to the driver’s short night sleep, the “unnecessary” emergency braking operated after Korso, the power regulation fault in the locomotives, the exceptional running route, the running late of the train, and the combination of the main, distant and figure signal aspects, being difficult to interpret.

The investigation of the hazardous situation has focussed not only on the incident itself but also on the usability and intelligibility of the new signalling system adopted in Finland. Furthermore a comparison was made with the operating principles of the signalling systems used in some other European countries in view of possibly discovering some guidelines for the developing of the Finnish system.

In the end of this investigation report, the Investigation Committee sets out its recommendations for improvements in terms of train safety. The recommendations suggest that the signalling system be simplified, the “proceed sn 35” aspect be rendered more distinct from the other signal aspects, the stopping times of the trains be lengthened, and that a 80 km/h speed limit be adopted when running without an ATC system in operation.

Recommendation S105
Recommendation S106
Recommendation S107
Recommendation S108