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Published byInge Dharmawijaya Modified over 6 years ago
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Reviewing differential speeds: potential route linespeed improvements
STE-PR V/T SIC seminar Reviewing differential speeds: potential route linespeed improvements Mark Burstow Principal Vehicle Track Dynamics Engineer December 2017 December 2017
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RSSB T996: Sprinter differentials
STE-PR V/T SIC seminar RSSB T996: Sprinter differentials T996 (2014) recommended characteristics to define ‘sprinters’ on GB railway Useful for new vehicles Did not address reasons for SP differentials on network How can we determine if current differentials on infrastructure are appropriate? Original reason for application of SP differential may not be clear Following renewals/enhancement original reason for differential may no longer exist Could it be acceptable to raise linespeed to SP differential for all traffic in some cases? December 2017
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Bottom-up approach: sample route
STE-PR V/T SIC seminar Bottom-up approach: sample route Request from V/T SIC: Can we do a ‘bottom-up’ approach to determine the ‘design’ speed profile for the current infrastructure? Choose York – Scarborough Currently has SP differentials applied Candidate for operating wider range of vehicles whilst maintaining current timings e.g. Class 185 restricted to lower speeds December 2017
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Current infrastructure data
STE-PR V/T SIC seminar Current infrastructure data Curvature Things that have an impact on linespeed: York Malton Seamer Scarborough December 2017
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Current infrastructure data
STE-PR V/T SIC seminar Current infrastructure data Things that have an impact on linespeed: Curvature Switches & crossings December 2017
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Current infrastructure data
STE-PR V/T SIC seminar Current infrastructure data Things that have an impact on linespeed: Curvature Switches & crossings Level crossings December 2017
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Current infrastructure data
STE-PR V/T SIC seminar Current infrastructure data Things that have an impact on linespeed: Curvature Structures Switches & crossings Level crossings December 2017
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Current infrastructure data
STE-PR V/T SIC seminar Current infrastructure data Things that have an impact on linespeed: Curvature Structures Switches & crossings Signals Level crossings December 2017
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Current linespeed profile
STE-PR V/T SIC seminar Current linespeed profile December 2017
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Criteria for speed assessment
STE-PR V/T SIC seminar Criteria for speed assessment Linespeed principles (for infrastructure) laid down in NR/L2/TRK/2102 ‘Design and construction of track’ Track category definitions Cant deficiency limits Cant/cant deficiency ratio Rate of change of cant deficiency Track components: Rail weight/section Jointed/CWR Sleeper types Fastenings Gauging Structures (RA rating) Signalling limitations Signal spacing Level crossing approaches December 2017
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Infrastructure issues
STE-PR V/T SIC seminar Infrastructure issues Jointed track Will limit linespeed and cant deficiency Only 2 sections of jointed track- both within ‘station limits’ December 2017
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Fragile infrastructure- LTSF
STE-PR V/T SIC seminar Fragile infrastructure- LTSF LTSF: Local track section factor Used in VTISM to account for different geometry deterioration rates Can be used to identify locations where geometry is sensitive T996 report suggested LTSF as an indicator of fragile track: LTSF<1 suggests good track performance: could be used to challenge SP differential LTSF >2 suggests worse than average performance: a case to impose SP differential December 2017
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Track categories Track sections allocated a ‘Track Category’
STE-PR V/T SIC seminar Track categories Track sections allocated a ‘Track Category’ Based on speed and tonnage carried Prescribes frequencies for maintenance/inspections Assume do not want to change Track Category What linespeed is possible without increasing maintenance burden? December 2017
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Linespeed: cant deficiency
STE-PR V/T SIC seminar Linespeed: cant deficiency Possible linespeed profile based on 50:50 cant/cant deficiency ratio In many cases the linespeed is limited by the Track Category speed December 2017
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STE-PR0033-00092 V/T SIC seminar
Ongoing work Work so far suggests that there may be a good case for raising linespeeds, but… …need analysis to consider (e.g.) Track construction Structures Signal spacing Level crossing and UWCs Gauging December 2017
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