The block is a 'corridor block' - which means no trains (passenger or freight) will run in that period. All routes have a corridor block everyday for monitoring and maintenance.
With increase in traffic, most major routes are not getting sufficient time for maintenance. A few years, there was a flurry of accidents in SR, as track maintenance was not done properly due to lack of sufficient corridor block period.
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That said, they could have rationalized the halts and altered schedules to get sufficient maintenance time instead of cancelling trains.