SYSTEM INTEGRATION TESTING IN THE FACTORY FOR TRAIN CONTROL AND SIGNALING SYSTEMS

Complex and large brownfield or greenfield signaling projects require a robust test regime to mitigate deployment risks, reduce delays to migration and reduce operational risks. Specifically, tightly coupled wayside and onboard signaling systems like CBTC signaling systems require a test regime that focuses on resolution of all major non-conformances, a.k.a., software/hardware defects, prior to deployment at site. While the technology has been advancing and agencies are ready to adapt, the contractors and suppliers who provide this technology are constantly persevering to improve their system integration approach. Integration risks increase when new functionality and / or new hardware are introduced. In addition, absence of a robust productization strategy by the supplier results in the supplier integrating the entire signaling system on every project, leading to additional time and cost for the agency. To achieve a robust integration approach and test regime, the factory test setup and integration test setup must mimic the real-world system as closely as possible. This includes integration of: 1. The signaling subsystems that make up the core signaling system, 2. The core signaling system with external interfaces, e.g., the existing railway infrastructure, and 3. The core signaling system with types of rolling stock the agency uses for operations and maintenance. Factory testing begins with validating that the hardware is built to specification, followed by validation of software and interfaces. System integration and functional testing may be performed using a virtualized environment instead of target hardware. In fact, some signaling system suppliers have moved from using the target machine factory setup to using Virtual Machine (VM) environment for their factory testing. There are several advantages with utilizing the virtualized environment for factory testing and software interface integration. To mitigate the risks involved with a purely virtualized environment for system integration, a mix of target and VMs for system integration may also be considered. This paper will discuss the different approaches to system integration, while considering the advantages, disadvantages, risks, and mitigations for these approaches, ultimately resulting in a smooth migration to the new/upgraded signaling system, highly desired by agencies, and safe operations at site. This paper will also touch upon the advantages of integrating the signaling system hardware and functionality as a product, to be deployed on multiple projects, and the advantages of product integration for projects and hence to the agencies.