Drivers are not to be blamed for delays; They are under strict orders to maintain certain speeds between stations or 'block sections' If there is delay it may be because of track conditions, delayed trains ahead of them, which locks signals for the trains behind them. When this happens i.e. when trains are delayed, controllers look to see whether a normally running train can overtake them at an intermediate station. Drivers do not normally intentionally slow down trains unless there is some technical snag which has to be reported in writing. In order to protect data, all diesel/electric locos are now fitted with computer based recording devices which record the acceleration rate,deceleration, with date and time stamps.. this is compared with the data already logged into the system by the Train Control Office (someone more informed may elaborate on this). Trains into north ARE delayed in months of Jan/Feb due to...
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fog conditions... and after a few accidents... drivers have been instructed to maintain visible conditions before passing THRU signals also. If there is apprehension about visibility, and Working Time Table shows train ahead of them... they will slow down irrespective of the 'passing through guidelines' based on the principle of SAFETY FIRST. When doing this over-ride of regulation of speeds, they have to justify in their log books why they are delaying .. and this is countersigned by the guard. Note also that passing thru stations also record visibility signed by the concerned Station master. Therefore, the scope for drivers to deliberately slow down trains gets counter checked in multiple locations. Of course the results are not visible immediately but the ultimate report goes to the DRM who then initiates action IF rpt IF there is some mis-match in the data collected. This has been computerised to a large extent, but scope still exists for making it real time data for quick analysis and consequent action where drivers are 'deliberately' delyaing trains. It is NOT a simple case of drivers slowing trains deliberately. Good wishes.