I think your problem is in ct19: You have this:
ct19: forall(p in plant, k1 in truck, k2 in truck : k1 != k2, j1 in jobs, j2 in jobs) //only one tuck can load RMC at the same plant/time
{
...
forall(p in plant, k1 in truck, k2 in truck : k1 != k2, j1 in jobs, j2 in jobs)
...
}
You have nested these two forall statements. This will result in a large number of combinations of all these indices. I guess you don't want the second forall to be nested into the first one but to be it on the same level:
ct19: forall(p in plant, k1 in truck, k2 in truck : k1 != k2, j1 in jobs, j2 in jobs)
{
...
}
ct19_2:
forall(p in plant, k1 in truck, k2 in truck : k1 != k2, j1 in jobs, j2 in jobs) {
...
}
Note that some other constraints seem to suffer from the same issue.