Resumen
The urban transportation network is susceptible to degradation in its performance because of various measures. It would be of interest to a planner if this risk can be quantified. In this paper, we present a methodology to do so by estimating the n most probable states of a network. A particular network state is a combination of capacity levels on all links and is defined by defining the different capacity levels at which all the links are operating at. The probability of occurrence of that state would be the product of probabilities of occurrence of capacities of all links. Suppose there are m links and n capacity levels. Each link can function in any of the n capacity levels. So the maximum number of states enumerated would be nm. A most probable state (MPS) is that state which has highest probability to function on a network. For each state consequence were found out. Consequence is the extent of variation from the minimum system travel time. Thus a graph is plotted between the consequence and the probability of its occurrence for all the states of the network. Risk associated to the network is defined by the probability for an event of negative impact to occur and the extent of the resulting consequence once this event has taken place. The routing assumed was static user equilibrium.