Increase in axle load of freight wagons

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Increase in axle load of freight wagons

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CC 8 2 LOADING

• In order to enhance throughput to meet increasing
  traffic demands, Board has permitted running of
  BOXN BOXNHS wagons loaded up to CC82(axle
  load of 22.82t) at maximum permitted speed of 60
  kmph on identified iron/other ores routes w.e.f.
  May ,05 as a pilot project for a period of one
  year initially (currency of the project has
  been extended up to June,08).
• Initially,16 routes were identified for such
  operation. Gradually, more routes were cleared
  totaling to 34 routes up to March ,07 on ER,
  SER, SCR, SWR, ECoR, SECR, SR WCR as per list
  in the annexure I.
• However, a number of precautions and monitoring
  mechanisms have been prescribed for these trains.

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CC 62 LOADING

• To achieve further augmentation in throughput,
  Board has approved universalisation of running
  of CC62 t loaded BOXN,BOXNHS,BOBR,BOBRN,BCN,
  BCNA, BCNAHS BOST wagons for carrying
  coal,cement,rice,sugar etc. at maximum permitted
  speed of 60 kmph, except some sections where it
  will be restricted .
• Restricted sections are given at Annexure II.
• In case of emergencies such as accidents etc.
  running of CC62 loaded wagons in some
  restricted sections can be permitted. This shall
  be done at the level of PCE , who will advise
  suitable speed restrictions keeping in view the
  condition of fixed infrastructure.
• The precautions and monitoring prescribed for
  these sections are essentially similar to those
  prescribed for CC82 axle load.

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Precautions and Monitoring Mechanisms

• Installation of electronic in-motion
  weigh-bridges at loading points to stop
  overloading.
• Installation of adequate number of Wheel Impact
  Load Detectors (WILD) for recording of loading
  spectrum passing over track.
• Ultrasonic testing of rails for detection of
  gauge corner cracks.
• Quarterly review of the project by a
  multidisciplinary committee comprising of PHODs
  under GM of Zonal Railway.
• Monitoring of defect generation rates in rails
  and welds based on USFD testing.
• Monitoring systems to be installed at identified
  Bridges.
• More frequent track recording to monitor track
  geometry.

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Important technical parameters

1. Track structure Minimum 52/60kg 72 UTS rails,
   sleeper density M7 and depth of ballast cushion
   250mm with a clear cushion of 100mm for running
   of these freight trains at maximum permissible
   speed of 60 Kmph . In case of 90R rails , maximum
   speed permitted shall not exceed 30 Kmph .
2. Bridges Mostly of BGML standards are available
   on these sections.

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Specific items for action ,monitoring recording
observations

• TRACK
• 90R rails should be replaced expeditiously as
  possible . While renewing rails, rails of 90
  UTS may be used from overall economics
  consideration as rail life will get shortened due
  to increased stresses .
  
• Similarly, while replacing sleepers, sleeper
  density of 1660/km may be provided.
  
• Ballasting will have to be given thrust.
• Structural integrity of fastenings has to be
  ensured especially rubber pads.

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Specific items for action ,monitoring recording
observations

• v). As a good maintenance practice ,it may be
  desirable to destress LWRs twice every year ,
  once before winter and again before summer
  especially in Zone III Zone IV.
• Behaviour of LWRs would have be watched
  critically and data collected.
  

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Specific items for action,monitoring recording
observations (Contd.)

• vi) Due to increase in lateral forces on curves,
  increased deterioration in lateral alignment
  would occur.
• Hence, curves may have to be inspected
  more frequently .

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Specific items for action ,monitoring recording
observations (Contd.)

• vii)Due to increased bogie rotational resistance,
  rail-wear on curves will increase. Rail profile
  would be required to be monitored to understand
  rail-wear pattern. On curves, increased angular
  wear may be dangerous and need to be watched.
• The observations of rail wear will be
  useful in decisions for rail replacement.

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Specific items for action ,monitoring recording
observations (Contd.)

• viii) Due to increased load ,rolling contact
  fatigue (RCF) defects viz. head checks gauge
  corner cracking would occur resulting in more
  rail failures.
• USFD examination of rails at more frequent
  interval would be required to be done.
  
  As a preventive measure, rail grinding will be
  helpful to eliminate such defects.

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Specific items for actions,monitoring recording
observations (Contd.)

• ix) Rail/wheel impact forces due to defects
  in the rail/wheel surface, viz. dip at rail
  joint, cup formation in AT welds, flat tyres, out
  of round wheels will increase damage to
  rail-heads, fishplates, bolt-holes and fish-bolts
  , sleepers ballast. These will cause increased
  deterioration in track geometry.
  Since the track is going
  be overstressed, Wheel Impact Load Detectors
  should be installed at suitable locations to
  prevent further overstressing.

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Specific items for action ,monitoring recording
observations (Contd.)

• x) Rail corrugations may develop due to
  high dynamic forces.
• These would have to be monitored and if
  necessary, rail grinding may be done to eliminate
  the same.

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Specific items for action,monitoring recording
observations (Contd.)

• xi) Points crossings maintenance
  activities will get increased viz. packing,
  correction to alignment/level, replacement/
  reconditioning of switches crossings .
• Due to increased bogie rotational
  resistance, the increased lateral forces may
  increase the tendency of derailment on a weak
  turn-in/turn-out curve, by gauge spreading.
• Thus, PC will require close monitoring.

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Specific items for action,monitoring recording
observations (Contd.)

• xii) Transitions, viz. bridge approaches,
  level crossings, culverts, tunnels etc., where
  the track stiffness changes abruptly, will
  require special monitoring due to abrupt change
  in vertical dynamics of heavy wheels.

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Specific items for action,monitoring recording
observations (Contd.)

• FORMATION
• Weak stretches of formation would have to be
  rehabilitated by providing blanket layer as given
  in RDSO Guideline GEG-6.
  Till such time it is done, frequent
  monitoring of the track geometry at such
  locations should be done.

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Specific items for monitoring recording
observations (Contd.)

• BRIDGES Each bridge would have to be evaluated
  as an individual identity reg. safety vis-a-vis
  its physical condition.
• Speed restriction may have to be imposed
  from safety consideration,if required.
• Rehabilitation/strengthening should be
  carried out as per the increased trailing loading
  density of 8.51 t/m .
• Sample vulnerable bridges should be got
  instruemented through specialised agencies .
• NDT tests may be carried periodically.

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Specific items for monitoring recording
observations (Contd.)

• Extra maintenance effort would be
  required due to increase in inspection,monitoring,
  maintenace of track,formation and bridges.
  Therefore, a proper record should be kept costs
  worked out so that proper evaluation can be done
  at the end of the pilot project.

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Conclusion

• RDSO should be associated in the studies and
  monitoring exercises.
• Railways should put in place the monitoring
  mechanism by the Monitoring Committee comprising
  of PCE/CE,CME,COM under GM .
• Instructions for installation and functioning of
  weigh bridges for detecting overloading of wagons
  have to be meticulously observed