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The general framework of capacity and travel time reliability of urban road networks is proposed by introducing the zonal reserve capacity as a measure index to network capacity and service level. Mathematically, the zonal reserve capacity is formulated as a bilevel model, in which the travel time requirements are converted into explicit link capacity constraints by adding dummy links to origin-destination (O-D) pairs. The integrated reliability of capacity and travel time is well defined under the circumstances of stochastic variation of link capacity or the demand pattern. The proposed model generalizes the capacity reliability and it also includes travel time reliability as a special case. Finally, the Monte Carlo simulation method is used to calculate the reliability and a numerical example is provided to illustrate the application of the model.