
How do you replace a critical railway system without disrupting daily operations? LINEAS faced this challenge when security vulnerabilities made its legacy application difficult to maintain. With AI-assisted software development, SumZero found a way to modernise the system faster while keeping railway operations running.

LINEAS relies on a business-critical application to support railway signalling and manage track personnel. When security vulnerabilities in the ageing system could no longer be fixed, replacing it became necessary. SumZero used AI-assisted software development to rebuild the application up to three times faster, without interrupting railway operations.
The existing application was built on outdated technology that could no longer be maintained securely. Fixing the vulnerabilities required more than a few updates. The underlying system had to be replaced.
The migration was complex. The old application relied on a database that stored information in an unstructured format. Moving to a modern system meant reorganising that data while preserving its integrity and compatibility with the existing mobile application.
Most importantly, the railway operations that were depending on the system had to continue without interruption.
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AI-assisted engineering accelerated the system rewrite by up to 3 times
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Critical security risks were resolved without downtime.
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Automated workflows cut development overhead by over 60%.
Instead of adding AI to the application itself, SumZero used AI to improve the software development process.
AI workflows supported the entire rewrite, from analysing the existing system and planning development tasks to generating code, testing and verifying the results. A multi-agent framework automated much of the coordination and repetitive work involved in traditional software development.
Experienced developers remained responsible for architectural decisions and code quality. Meanwhile, the team migrated the existing data to a modern, structured database and maintained compatibility with the mobile application throughout the transition.
This approach reduced manual work and development overhead without compromising the reliability of a system that railway operations depend on.
LINEAS now has a modernised application thataddresses the critical security vulnerabilities of its legacy system. Thetransition took place without interrupting operations, and existing mobileusers could continue working throughout the process.
AI-assisted development accelerated deliveryby up to three times compared with traditional development, while reducingdevelopment overhead by more than 60%.
The project also established a repeatableapproach to AI-assisted software development that can be applied to futureengineering projects.


