/* POSITIONING OF BEARERS PRECEDE FILLING. */
  model.add(V1.startsAfterEnd(T1));
  model.add(V2.startsAfterEnd(T5));
 

Some of the temporal constraints specify minimal and maximal delays between start and end times of activities. For example, the following statements specify that no more than -3 days can elapse between the end of a particular foundation (or excavation for the pillars with no foundation activity) and the beginning of the corresponding formwork.

  model.add(A1.endsAfterStart(S1, -3));
  model.add(A2.endsAfterStart(S2, -3));
  model.add(P1.endsAfterStart(S3, -3));
  model.add(P2.endsAfterStart(S4, -3));
  model.add(A5.endsAfterStart(S5, -3));
  model.add(A6.endsAfterStart(S6, -3));
 

The negative delay A1.endsAfterStart(S1, -3); can be read as "A1 ends after the start of S1 minus three units of time." This states that no more than 3 days can elapse between the end of A1 and the beginning of S1.

Another particular constraint is the one that states that the delivery of the preformed bearers occurs exactly 30 days after the beginning of the project. As we can arbitrarily decide to use 0 as a beginning date for the start of the project, this constraint translates into setting the start time of activity L to 30. This is done by simply setting a lower bound for the start time variable of L, like this: L.getStartVariable().setLb(30).