Statistical Analysis of Driver Incidents
Clients: Various British train operators, 1999 - Ongoing
One of the key risks on the railway is when drivers, for whatever reason, do not obey signals or other operating instructions such as stopping at particular stations. Fortunately, these events are rare, with years of historical development having designed out many of the potential causes, whilst the introduction of the TPWS system has also much reduced the potential implications. However, train operators are correctly still concerned to understand the types of condition which lead to these incidents. There are perhaps two main types of analysis which might be carried out to understand the issue more fully - behavioural analysis of individual members of staff, and statistical analysis looking at a wider range of incidents and near misses, of which Signals Passed At Danger (SPADs) are amongst the most-recorded.
The Railway Consultancy has undertaken this latter type of analysis for a number of train operating companies, which requires a good understanding of both railway operations and statistics. Our method involves the development of plausible railway operating hypotheses, and the application of chi-squared statistics to them; it compares the actual number of SPADs with the number which would be expected given the characteristics of the situation. For instance, if a train operator has twice as many trains of type x as type y, one would expect twice as many SPADs involving trains of type x as of type y. If this is not the case, one then needs to consider why this is the case and what might be done to remedy the situation.
A particular area of development of our work has been in the analysis of drivers’ shift patterns. Although some aspects of driver management are heavily-regulated (e.g. the number of hours driven per shift, or hours between shifts), there are fewer limitations about the construction of rosters; for instance, the movement of shifts around the clock during a period of consecutive days is not prescribed, whilst other rules (e.g. regarding Sunday working) can make some shift patterns at best unpleasant. In fact, our analysis has demonstrated that a number of train operators have shift patterns which appear to be contributing towards the propensity of train drivers to have incidents, and we have made specific suggestions to a number of companies about the ways in which rosters might be put together to minimize this problem.
Last updated: Sunday, 18th December 2016
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