Recently, researchers in the eld of transportation network planning have become increasingly interested in network reliability, publishing research works focused on the calculation of various types of network reliability. Calculation of network reliability has led the transportation network optimizers toward new approaches in which the maximization of reliability is considered as an objective. Travel time reliability is among the most important reliabilities investigated when analyzing urban transportation networks. For this purpose, various approaches have been taken based on di erent assumptions proposed. In the present research, the uncertainty associated with the demand for travel and the ows passing across links along with the correlations among the links comprising a route were considered in order to calculate the travel time for each of the network links. Moreover, it was observed that the process followed Shifted Log-Normal (SLN) distribution. These calculations are hoped to serve as a basis for the employment of travel time reliability within the modeling of transportation systems so as to increase the accuracy and reliability of simulations. The results were validated by an urban network with 12 nodes, 21 links, and 4 origin-destination pairs. Travel time reliability assessment was conducted by calculating travel time over all the forming links.
