146 Managing projects as investments: Earned value to business value
required to do each work activity. This new drag is resource availability
drag (orRAD), caused by specic bottlenecks of specic resources during
specic timeperiods.
Sometimes additional resources are unobtainable. But much of the
time they simply require nancial justication. If our project has been
allocated Henry the Hobbit only half-time, what is Henry doing the rest
of the time? If he’s assigned to another project, what would the impact be
on that other project? It is quite possible that Henry’s work on the other
project is completely off the critical path with lots of total oat. (This,
of course, is another way in which multiproject organizations that don’t
ma