Application of Queuing Theory Models in Planning of Transportation Terminals

This study constitutes an analysis of the application of the Queuing Theory Models in the context of planning of transportation terminals. When the volume of traffic desiring service at the terminal exceeds the capacity of the service facility, queues inevitably occur. Time spent queuing is economically undesirable, while on the other hand, there will be costs associated with idle service facilities.

A major purpose for studying queues is to enable prediction of what would happen, if certain parameter changes are made within the system or its components. Another reason is to gain an understanding, which may assist planners in developing methodologies that may improve the system in some way, thereby attaining a balance between waiting and service costs.

The Principles of Queuing Theory and its mathematical fundamentals are outlined. Field measurements, computations and analysis of Queuing data from an existing weighbridge terminal are presented.

Data analysis reveals that inter-arrival and service times are exponentially distributed, and the system's performance parameters are functions of the arrival rate, service rate, the number of servers and the system's optimum capacity.

The study indicates that the proportion of time the facility remains idle depends on rate of arrivals, rate of departures and on the number of operational servers. Employing a high number of servers results in high proportions of idle time being experienced at the facility. It is, therefore, more economical to increase the rate of offering service rather than to increase the number of servers.

It has been shown that Queuing models can be used in the determination of proposed future models of transportation terminals, and the optimum spatial size for maximum operational efficiency for an existing weighbridge has been (determined. An operational weighbridge terminal has been re-designed using performance parameters determined from field observations, its efficiency tested and the potentials for designing minimum - cost models demonstrated.

It is proven that Queuing Theory models can be used as objective, reliable analytical decision-making tools in land-use planning and management.