A demand model based on the concepts of transit accessibility and route directness was developed. Transit accessibility was expressed in terms of transit service coverage and transit service frequency. Route directness, on the other hand, was measured by a meandering penalty. The two measures were then combined into a single index, on which the estimation of transit demand was based. The development of the current model ensures a sensitive relation between the design of network configuration and the estimation of transit demand, therefore providing transit planners a better tool in bus network design.