The master schedule says what must be finished. The three-week lookahead says who will do what, with which crew, on which day. When the two drift apart, the site stops using the schedule, and the schedule stops describing the site.
What a good lookahead does
- Stays tied to master activities, so it cannot quietly become a second schedule.
- Breaks each activity into steps with a named crew.
- Lets steps overlap where the work really overlaps.
- Shows clearly whether the steps still fit the master duration.
When the steps no longer fit
If the steps run past the master duration, that is not a field error. It is the earliest warning you will get. The scheduler should see it, check the effect through the logic, and either accept it or send it back with a reason. Silently keeping both versions is how a schedule loses its credibility.
See the field lookahead on a phoneIs your own schedule healthy?
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