Allows pipes to randomly fail. If a failure occurs, the failure costs (repair + damage) are calculated and subtracted from the budget. Note, that this may result in a negative budget.
fail(state, prob.failure)a state object
function returning the annual failure rate; i.e. the probability of a
pipe failing in the current year of simulation.
prob.failure must take age, age.last.failure, n.failure as input arguments.
Note that in the case of a pipe with zero previous failures (i.e. n.failure=0),
age.last.failure=NA.
inventory with new failures