Application of Equivalent Trunks Technique to Alternate Route Engineering

The grade of service of an alternate route is normally based on the average of several hourly blocking probabilities of the alternate route. The contemporary method for estimating the grade of service of an alternate route requires adjustment to the average traffic loads with appropriate correction factors in order to gain sufficient accuracy. This paper introduces the equivalent trunks technique, which can be used for approximating the alternate route grade of service without the need of adjustment to the average traffic loads. Thus, the technique is simple to use. In comparison with the results obtained by the present relatively complex method and the measured data, this technique is shown to give good accuracy. It is suggested that the preparation of engineering charts based on this technique would considerably further enhance the simplicity of its use for alternate route engineering.