Creating a testing process, certifying, and developing software for a railroad system of SIL4 (Security Integrity Level)

What did the client need?

The client wanted to update their present HW-SW (hardware-software) product to expand to a new market. They were searching for a reliable partner to provide them with a complete set of development and testing services and support the process of certifying the product.

The partner had to be able to provide a complete service of developing safety-critical software for the purpose of railroad traffic. Due to the scale and level of innovation of the project, the support was to extend beyond just technical or procedural competences, but most importantly, finalizing the process by certifying the product and complementing it with thorough documentation.

The software was to be produced for already existing hardware.

The system’s purpose was to control the occupancy of rail sections by detecting the passing trains and it was required to follow the CENELEC SIL-3 and SIL-4 standards.

We accepted this challenge. We used the client’s team’s extensive knowledge of the railroad industry and the potential for product development. We proved to be a reliable partner by delivering high-quality programming services based on modern hardware solutions.

What we offered

Our complete support included two complex projects: one for development and one for testing.

Due to the lack of a precise specification, we started off by setting expectations concerning the software to be created. Eventually, the project was divided into two stages with a well- defined scope to be delivered. We commenced with analytical workshops that were aimed at preparing product cards for each of the application components. They were utilized both at the development stage as well as during the approval of individual work phases. In parallel to the development process, application tests were also carried out.

The team scaled throughout the project to optimize the speed of delivery. At all times the team involved a project manager, a business analyst, and a tester. The custom software development team consisted of 4 programmers and 1 architect.

Sprint Business Reviews were held every week. On top of that, the client was granted access to the project’s JIRA, so they were fully up-to-date with the progress of the works.

Project 1: software meeting the highest security standards

The project objectives:

  • monitoring and occupancy control of railroad sections;
  • controlling the safety of trains;
  • integration with the client’s new HW platform;
  • safety-critical software.

What we delivered:

  • firmware meeting the requirements of SIL-4, the ISO50128, and ISO50159 standards;
  • developing the code crucial for communication and security;

The effect of the project:

  • developing embedded software – designing, expanding, and integrating with the railroad signaling system devices.

Project 2: software tests meeting the highest requirements of SIL-4 in railroad security.

The project objectives:

  • designing the entire process of software testing;
  • test execution;
  • preparing testing result reports for the purpose of certification.

What we delivered:

  • multi-level tests;
  • a complex testing framework for the system;
  • developing the architecture, code, testing strategy, test plan, test assumptions, and cases;
  • test automation structure (testing bundles, intermediate code, and test cases);
  • fully developed and documented test processes;
  • defining and implementing code coverage and static analysis tools;
  • test and development documentation schemes;
  • implementing DOORS in the area of testing and development;
  • well-organized testing and the reporting mechanism;
  • the laboratory (mean power density of 200W/m2),
  • technical documentation for testing procedures and test results.

The effect of the project:

  • multi-level testing and integration validation;
  • successfull TÜV SÜD audits,
  • supporting the system homologation process;
  • implementing the new culture of developing software based on automatic testing;
  • an efficient and reliable process of testing and defect reporting.

What we achieved

The product received the TÜV SÜD certification and the testing process was successfully verified and accepted by the proper certification body.

When our engineers relieved the client’s team of some of its workload it was able to focus on its other tasks. Our proposed solution: complementing the team with scalable resources provided on-demand, resulted in optimizing the cost of software development.

Solwit S.A. was responsible for the implementation of part of the embedded software for the system, in accordance with the rigors of the industry railway standards, and for ensuring the quality of the software in an automated test environment. Today, the UniAC (2) system is implemented by railway line operators all over the world, ensuring rail traffic safety in line with standards. Currently Solwit, as a permanent partner of Voestalpine SIGNALING, participates in the processes of further maintenance and development of the system, at the same time providing support in adapting the solution to the requirements of individual target markets.

Przemysław Wołoszyk, Development Director, Voestalpine SIGNALING Sopot Sp. z o.o.

The system contains the following functional modules:Six months after launching the cooperation in creating the embedded system the client offered us to expand the project by three additional engineers to include software development and testing for an application for configuring the system. It was also crucial to provide support in certification – we represented the client in the TÜV SÜD certification for the testing process. We have continued to support the engineering team of Voestalpine since 2015.

During this cooperation, the software has passed certification and the system has been successfully introduced to the market. Voestalpine has operated with high-quality software aligned with the CENELEC SIL-3 and SIL-4 standards, meeting the highest functionality and security requirements for systems controlling railroad section occupancy.

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Creating a testing process, certifying, and developing software for a railroad system of SIL4 (Security Integrity Level)
Industry and country
Project scope
safety critical
software testing
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