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Enabling Shared-Track: Technology, Command, and Control 31 5) Train Control Technology--The Supply Side The process of creating a practical train control system is lengthy and expensive. Designs must be prepared, products manufactured, components assembled and installed in the field, and the system tested. Since the dominant issues include products and installation, the supply side is often the most significant of all to stakeholders. The signal supply industry falls into three major categories: Large, full-service suppliers; Niche or specialty product vendors; and Procurement consultants. System suppliers and consultants assume primary responsibility for transforming operat- ing requirements, standards, regulations, and design parameters into a functioning train con- trol system. The supplier is responsible for the most important phases of implementation: manufacture of hardware, assembly of components, and system testing. Once installed, sig- nal systems tend to have a long life cycle, and can serve reliably for more than 30 years with periodic maintenance and repairs. A long-term business relationship is the norm between the operator and the vendor, as specialized or proprietary parts often are necessary for repair and maintenance. This association is compounded by the vested expertise effect: when agency staff becomes accustomed to a particular product line, familiarity and experience often result in a sole-vendor relationship. 6) Proving the Train Control System Basic Testing Requirements New signal system installations must be proved in a succession of steps. The system is first cut-in by joining hard wire connections from rails to vital equipment in bungalows. Func- tionality is verified through a series of local and component tests. The tests are then gradually extended and combined to include adjacent interlockings. Once signal engineers are satisfied that the system is safe, test trains are run to confirm performance. There is nothing particu- larly novel about this sequence. The FRA establishes test requirements for signal system com- ponents and functions. 49 CFR Part 234.247 to 234.273 specifies Inspections and Tests for Grade Crossing Equipment. 49 CFR Part 236 specifies Inspections and Tests for various categories of equipment includ- ing Systems, Interlockings, Traffic Control Systems, and Automatic Train Stop and Cab Signals. While these requirements are geared towards regular maintenance and inspections, they are also the starting point for a new installation. Often a railroad will create a more detailed inspection and test plan tailored to its own installation. System and Integration Testing--Vendor Role Vendors also must test and prove other aspects of new train control systems, to verify per- formance and functionality. Such tests are witnessed or monitored by the operator, to authen- ticate the test performance and results. In a shared-track operation, such testing will be required with conventional rolling stock and the light passenger rail car. By this point all assemblies, components and equipment would have passed factory tests. Once in place on the railroad, there is typically a six-step field and wayside test and inspection program: (1) installation test- ing; (2) static testing; (3) integration testing; (4) dynamic testing; (5) design or field changes; and (6) retest.