Controlling the risk of derailments in S&C Brian Whitney Principal Engineer [Track & Civils] Network Rail brian.whitney@networkrail.co.uk 27 th November 2014 / 1
1-Dec-14 / 2
Introduction NR/L2/TRK/0053 issue 5 Inspection and repair procedures to reduce the risk of derailment at switches Purpose Facing switches require robust inspection procedures that drive timely maintenance intervention that will: minimise the risk of derailment maximise the asset life deliver good operational availability This specification describes the inspection regime, monitoring procedures, immediate actions and essential maintenance to be undertaken at switches to reduce the risk of derailment. It identifies the particular derailment hazards associated with switch wear and damage and the remedial measures necessary Recent changes to Switch Inspection to reduce the risk of flange climb derailments via a letter of instruction / 3
Why the changes? Derailments at Shrewsbury and Princes Street Gardens Need to control risk of flange climb derailments of all at risk facing switches Promote understanding of the risk associated with switches made from hardened steel grade Need to improve and reduce risk / 4
Biggest Risks Similar flexure turnouts a turnout radius of 300m and below and a through route radius of 1000m and below e.g. through line radius of 1700m, with similar flexure Dv turnout of 277m Not high risk by design Worn switches or switches experiencing high wear rates poor track geometry poor installation no or ineffective lubrication / 5
Assessment to Identify Switches which present the highest NR/L2/TRK/0053 - Inspection and repair to reduce the risk of derailment at switches Detailed Inspection Interval Risk Assessment Location: RH/LH ELR: Miles Yards risk Produce a register of high risk switches by each DU Action: subject high risk switches to 8,13, 26 and 52 weekly detailed 053 inspections Interval can be varied by risk assessment by TME Point No: High Risk/ Non High Risk Normal/AMS/MHT/HP Item Factor Risk Level Comments 1 2 3 4 5 6 7 8 Overall Assessment All red All orange or red 1-4 greens 5-9 greens All green Flexure Through route radius Turnout radius S053 History Traffic density in facing direction Number of tracks (including all tracks that could be affected Route environment Traffic type 9 Track geometry 10 Switch rail condition Action Through route speed (mph) Turnout speed (mph) SF- Similar Flexure CF- Contraflexure TS- Out of Straight <300m 300-1000m >1000m <300m 300-1000m >1000m 053 related derailment Repeat S053 failures Never repaired / Last remedial work past 12 months More than 50 per day 20-50 a day Less than 20 a day Running lines including more than 2 tracks Running lines up to 2 tracks or sidings Totally within sidings Within 200m on the approach side of a major structure, station or embankment / On Viaduct Cutting and/or within 200m on the approach side of an underline structure Open Freight and passenger Passenger Freight Very poor Poor Satisfactory Worn / high wear rate Uneven wear Noticeable wear Carry out detailed inspection at 8 weeks interval* Carry out detailed inspection at 13 weeks interval* Carry out detailed inspection at 26 weeks interval* Carry out detailed inspection at 52 weeks interval* No specific detailed inspection needed unless required by the SM(T) walk Through route radius (m) Turnout radius (m) * Frequencies may be risk assessed by the TME and may be reduced/increased as appropriate depending on deterioration rate / 6
Risk Assessment 9 questions. NR/L2/TRK/0053 - Inspection and repair to reduce the risk of derailment at switches Detailed Inspection Interval Risk Assessment - Only for High Risk Switches Location: RH/LH ELR: Miles Yards Point No: Normal/AMS/MHT/HP Through route speed (mph) Through route Turnout speed (mph) Turnout radius Item Factor Risk Level 1 2 3 4 S053 History Through route radius Track geometry Number of tracks (including all tracks that could be affected S053 related derailment Repeat S053 failures Never repaired / Last remedial work past 12 months <300m 300-500m 500-1000m Very poor Poor Satisfactory Running lines including more than 2 tracks Running lines up to 2 tracks or sidings Totally within sidings / 7
Cont Within 200m on the approach side of a major structure, station or embankment / On Viaduct 5 Route environment Cutting and/or within 200m on the approach side of an underline structure 6 7 8 Traffic density in facing direction Traffic type Switch rail condition Open More than 50 per day 20-50 a day Less than 20 a day Freight and passenger Passenger Freight Worn / high wear rate Uneven wear Little wear No grease or lubrication 9 Lubrication Presence of some grease Effective lubrication regime Overall Assessment All red Orange and red 1-3 greens 4-8 greens All green Action Carry out detailed inspection at 8 weeks interval* Carry out detailed inspection at 13 weeks interval* Carry out detailed inspection at 26 weeks interval* Carry out detailed inspection at 52 weeks interval* No specific detailed inspection needed unless required by the SM(T) walk * Frequencies may be risk assessed by the TME and may be reduced/increased as appropriate depending on switch deteriorat / 8
Other updates to switch inspection standards NR/ L2/TRK/0053 / 9
Revised Switch Blade Repair Angle 20mm down Current practice At least 5mm New requirement 40mm down < 2mm Contact angle of 44 76 Target region is the flange contact zone, i.e. between 20 and 40mm below the stock rail head. This is a top down grinding process i.e. aligning the grinding stones at the switch rail gauge corner and grinding downwards until the depth of 40mm to achieve a uniform angle of 65 at the critical region 76 65 / 10
Modifications to the Protractor Gauge 40mm depth mark 20mm depth mark Removal of the two wider spaced nibs 20mm depth mark 40mm depth mark / 11
Existing Protractor Gauges / 12
Modified TGP8 Gauge Currently the majority of TGP8 gauges only have the 60 line marked on the P8 profile. The additional two lines situated 2mm above and 2mm below the 60 line illustrate approximately the 65 and 55 contact angles, respectively 65 60 55 Switch Sidewear Angle < 55 50mm length or more Ban any facing moves < 60 200mm length or more 60-65 200mm length or more Ac@on As mandated in S053, apply lubrica@on and grind within 36 hours or ban facing traffic Grind within 13 weeks or monitor wear every 13 weeks / 13
2 Key Changes Hazard 5 Inspection Detailed inspection includes derailment hazards 1 to 5 for rail sections made from any grade of steel. Action: all high risk switches failing the hazard 5 inspection, the switch shall be ground within 3 days or ban all facing traffic; all other switches, the timescale is to be determined by the TME Clause 10.2 of NR/L2/TRK/053 (Issue 5) shall only apply to high risk switches that are: Newly installed premium grade steel Newly weld repaired (all grades of steel) / 14
Why change? High Performance (HP) Steel Switches are increasingly being used HP steel is of premium grade, a similar hardness as AMS and MHT Derailment Hazard 5 is of relevance and importance; the risk is relevant to all steel to steel contact between surfaces with significant differential material hardness Property R220 R260 350HT 400 MHH HP Crown Hardness (HB) 230-260 284 290 Consistent throughout section 350 390 388 401 340 350 Consistent throughout section Comparison of Steel Hardness / 15
AMS Switch Profiles that Led to Derailments Possible point where sharp edge on gauge corner bites into wheel Glasgow Central 1991, Pts 332A Din$ng 1990, Pts 16 Neither flange contact angle nor the rail sec@on type are relevant to this / 16
Why we must do better Edinburgh 2011 Avoid similar flexure turnouts Increase turnout radius where possible Zero cant if possible Shrewsbury 2011 Waterloo x 1 2007 Glasgow 2007 Victoria 2007 Waterloo x 2 2007 / 17 17
Complexity - It s Not Easy / 18
Thank You / 19