Analysis of German rail accident statistics for risk assessments

The statistics of German Federal Railways covering railway accidents in goods traffic from the years 1979 to 1988 and the records concerning accidents in shunting operations from the years 1987 to 1989, taking the marshalling yard in Braunschweig as an example, were evaluated in order to derive input data for a probabilistic safety assessment of transports of radioactive wastes to the planned KONRAD waste repository. The analysis of accident data had several objectives: 1) to derive the total accident rate per goods-train kilometer and per marshalled wagon, 2) to assign the accidents to an accident severity classification scheme, in order to derive relative frequencies of different accident severities, 3) to determine for goods-train accidents the number of wagons damaged above a threshold of DM 3,000 repair costs, 4) to determine the number distribution of wagons affected in goods-train accidents as function of severity category, 5) to derive the accident rate per wagon, expressed as accidents per wagon-km. Total accident rates of 0.5 relevant accidents per one million goods-train kilometers and 7.5 relevant accidents per one million marshalled wagons were established. Accidents considered as relevant were those resulting in material damage to railway vehicles exceeding DM 3,000. Over the period of 10 years examined total accident rates declined noticeably. An increase in accident rates was observed for speeds above 80 km/h due to a larger fraction of fast travelling goods trains. (J.P.N.)