Major factors affecting the reliability of railroad or transit systems are assigned at the design stage of a project. After the design of the system has been finalized changes that can be implemented to improve the reliability are generally of the second order level and subsequently have a lesser effect. An area that has traditionally been a source of unreliable operation for railroad and transit systems has been the interfaces between the various systems. The system-to-system interfaces cover the whole of the range of areas in a railroad or transit system and are often visible to the passengers using the railroad or transit system. The interfaces to be controlled have a wide variety of characteristics and features. These interfaces can consist of mechanical issues like for the platform and vehicle interface. The interfaces can also be mainly electrical in nature as with the control of conducted interference currents at the vehicle power supply interface to achieve compatibility. Interfaces may also be a mixture of mechanical and electrical characteristics. Railroad and transit systems are becoming more sophisticated, it is now common for a rail vehicle to have multiple microprocessors on board to control the various systems needed for a modern rail vehicle. Similar technologies are also being applied to different systems of a railroad or transit system. For example the technology required to control a vehicle propulsion system is very similar to that required by the modern regenerative substation. Modern integrated systems are also spreading across the traditional system boundaries. For example an integrated passenger information system for an LRT or Metro system would span vehicles, stations, train control and communication systems. A key factor to improving the reliability of a railroad or transit system is early and effective control of the system interfaces and having the appropriate organization(s) responsible for the interface. This paper will explore the factors that would need to be considered for appropriate management of the interfaces. It will relate the management of the interfaces to the types of contract mechanisms that can be used for procurement of equipment and consider the associated advantages and risks.

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