A transportation queueing process in which taxis arrive in a Poisson process and customers arrive as a renewal process independent of taxi-arrival process is controlled by calling extra taxis whenever the total number of customers lost to the system reaches a certain predetermined number. Transient and steady state behavior of this process is studied using renewal theoretic arguments. The optimum value of the control variable is also obtained so as to minimize the total cost to the system due to the waiting taxis and lost customers.