A new equilibrium model is proposed to determine the equilibrium market penetration of the advanced traveler information system (ATIS) in a network with heterogeneous users and elastic demand. User heterogeneity is considered by assuming a continuously distributed value of time (VOT) across users, and demand elasticity is considered by using a deterministic mode choice model for public transit and for equipped and unequipped private cars. The user equilibrium of mode choices for a given ATIS service charge, transit fare, and frequency is so determined that no one can reduce his or her generalized travel cost by changing to an alternative travel mode according to his or her own VOT. Furthermore, assuming provision of ATIS and transit services by competitive profit-maximizing firms, the market equilibrium is studied using game theory by determining each firm's service charge and service quality and its resultant market shares. Through numerical simulation, the benefits generated from a given combination of service charges and service qualities to transit and road users, transit and ATIS service providers, and society as a whole are investigated.