GB Rail SPAD Risk Ranking Overview

Transcription

1 GB Rail SPAD Risk Ranking Methodology BACKGROUND All category A Signals Passed at Danger (SPADs) are recorded in the GB Safety Management Information System (SMIS) and were historically assigned a severity ranking and a hazard ranking index based on what actually occurred as a result of the SPAD. However, the GB Railway Group Safety Plan for the period 2001/2002 adopted a riskbased target for the reduction of the potential consequences of SPADs as the existing ranking methodologies did not adequately measure this potential risk to passengers and staff. For this reason a SPAD Risk Ranking Methodology was developed in The SPAD Risk Ranking methodology was developed to provide a better understanding of the risk associated with SPADs: It estimates the probability of the SPAD escalating to an accident and the potential severity had an accident occurred It estimates changes to overall potential risk from SPADs across the network It identifies those SPADs that are potentially significant and potentially severe It also informs the SPAD investigation process SPAD Risk Ranking Origins and development ember 2002: The methodology for version 1 was developed and rolled out by RSSB with the training course and spreadsheet tool being developed by AD Little. e 2007: e 2008: Lloyd s Register Rail carried out an independent review of the methodology to establish industry views of the risk ranking process and outputs, and to review the effectiveness of the process. RSSB reviewed and revised the original methodology, based on recommendations raised by Lloyd s Register Rail, issues raised by assessors, and using risk data from the latest version of the RSSB Safety Risk Model. ember 2008: Version 2 of the SPAD Risk Ranking Methodology was launched in ember tember 2010

2 SPAD Risk Ranking Structure The methodology is divided into three parts: Part 1 Part 2 Part 3 Initial Collision Potential Assessment Rapid preliminary assessment of the direct collision potential of the SPAD. Assessment Result: Yes or No categorisation. SPAD Accident Vulnerability Ranking Assesses how close the SPAD came to an accident and what measures were utilised to prevent the occurrence of the accident. Assessment Result: Vulnerability Ranking letter A to K. SPAD Risk Ranking Assesses the potential risk from the SPAD considering the most likely of four potential outcomes: a) Collision with another train or buffer stops. b) Train derailment. c) Collision with a road vehicle on a level crossing. d) Train entering a possession with the potential for encountering workers on the track. Assessment Result: Overrun Probability Ranking, Potential Consequences Ranking and Overall incident risk ranking score 0 to 28. It is a requirement of Group Standard GO/RT3119 Accident and Incident Investigation 1 that Network Rail completes a SPAD Risk Ranking using the SPAD Risk Ranking methodology for every category A SPAD that occurs on Network Rail Managed Infrastructure. 1 See tember 2010

3 METHODOLOGY PART 1 Initial Collision Potential Assessment Rapid assessment Assesses whether or not the SPAD had direct collision potential Based on conditions at the time of the incident ction collisions only (Head-on and Head-on/side-on) Yes or No result Part 1 of the methodology is a rapid assessment as to whether the SPAD under investigation, bearing in mind the routes set at the time of the incident, had a direct collision potential. The Assessor answers the question: In this case following the Cat A SPAD, could the train, before it reached another stop aspect, have come into conflict with another train on a cleared route joining or crossing the route ahead of the signal passed at danger? The result for Part 1 is either Yes or No. METHODOLOGY Part 2 SPAD Accident Vulnerability Ranking Rapid assessment Highlights how close the SPAD came to an accident Considers potential junction collisions, rear-end and head-on collisions, accidents at level crossings, derailments and SPADs into possessions Result is an A K ranking The SPAD Accident Vulnerability Ranking focuses on the characteristics of the actual SPAD incident that occurred, highlighting how close the SPAD came to an accident and what factors were employed to prevent an accident occurring, eg. TPWS intervention. The output of the SPAD Accident Vulnerability Ranking is one of eleven categories, as shown below. Categories A to D indicate the conflict point was reached or passed by the SPAD train. tember 2010

4 METHODOLOGY PART 3 SPAD Risk Ranking More detailed assessment Measure of risk: considers both the potential likelihood of an accident and the potential consequences Considers potential junction collisions, rear-end collisions, accidents at level crossings, derailments and SPADs into possessions Needs information on the actual circumstances at the time of the incident Result is an incident risk ranking score 0-28 Part 3 considers the risk characteristics of actual SPADs, considering both the potential for an accident to occur following a SPAD and the potential consequences should an accident have occurred. The method is not a signal risk assessment, but an assessment of the risk characteristics of an actual SPAD incident. The SPAD Risk Ranking is based on a simple scoring system considering two main areas that influence SPAD risk: 1. The Overrun Probability Ranking covering the potential for the SPAD train to reach the first potential conflict point 2. The SPAD Potential Consequences Ranking covering the potential for injuries and fatalities should an accident occur The SPAD Risk Ranking score ranges from 0 to 28 (low risk to high risk respectively) The difference between two consecutive risk ranking numbers represents approximately a factor of two change in risk. tember 2010

5 SPAD risk as percentage of benchmark GB Rail SPAD Risk SPAD Risk Ranking Excel Assessment Tool A SPAD Risk Ranking Excel Assessment Tool has been developed to guide assessors in completing SPAD Risk Ranking Assessments consistently and accurately according to the methodology. It is used to collect all relevant assessment input data and it calculates results and exports them in the form of an assessment results sheet. Uses of the SPAD Risk Ranking Results The information generated by the SPAD Risk Ranking process is used in various ways: the SPAD Risk Ranking output is regularly reviewed by GB rail industry members, for example, by the Operations Focus Group. It is also presented in the Annual Safety Performance Report and it forms a key input into the modelling of SPAD risk in the RSSB Safety Risk Model. SRMv6 data period SRMv6 data period 140% 600 SPAD Risk Ranking Change in risk with TPWS (based on one year of SPADs) 120% benchmark date 01 Change in risk with TPWS (based on two years of SPADs) Number of NRMI SPADs in the last year % % 60% % High Risk SPADs - Didcot - Lugton % 0% Norton Bridge - collision % 8.46% TPWS installation Date SRMv5 data cutoff 05 SRMv2 data cutoff 01 End of TPWS installation effect on 1yr average End of TPWS installation effect on 2yr average k I stock removed from network 05 Further information To discuss any of the content of this briefing note or to request a copy of the new methodology handbook, please contact risk@rssb.co.uk. tember 2010