Advanced Train Control Systems (ATCS) bring economic benefit to railroads through the automation of existing procedures and the provision of new features. Many of these benefits are realized through integration of ATCS with the railroads' management information systems (MIS). The integration of ATCS with MIS poses technical challenges to both the ATCS community and the MIS community. The ATCS and MIS must adopt compatible data communication protocols. ATCS must be able to adapt to changes in the MIS community--among them, a move toward distributed and diverse systems. Being able to adapt to these diverse systems may require adapting ATCS protocol standards. The interface protocols must also provide for appropriate implementation of security procedures. The procedures must be provided to prevent breeches of security in either the MIS or the ATCS. This is necessary because of the sensitive business nature of MIS data and because of the safety-critical nature of some ATCS functions. Another technical challenge is the formulation of an appropriate strategy for distribution of information throughout combined ATCS-MIS. This strategy must account for the fact that ATCS have limited capacity for data transmission and that MIS applications share that capacity with other ATCS applications. Overloading ATCS data networks can seriously degrade the operational benefits that are the prime benefits of ATCS.