Stephen Ullom
Software ArchitectSummary
I’m Stephen Ullom, a software architect who has spent the last twenty years pulling order out of complex, physical systems. The kind of software where determinism, observability, and the gap between simulation and reality are not abstract concerns.
I work at the seam between business visionaries, domain experts, and software execution. I lead architecture, mentor engineers, align stakeholders, and ship software products built to evolve. I also heavily leverage AI-native workflows, from human-in-the-loop collaboration to fully automated agentic execution loops.
This site is itself a small showcase: spec-driven, statically rendered, and intentionally crafted, with a few easter eggs that hint at the kind of systems I love to build.
Experience
Lead Software Architect & Product Manager Alstom Transportation
- Led architecture and product strategy for a global suite of real-time rail simulation systems
- Modernized 4 legacy systems into scalable, containerized platforms (-40% maintenance cost)
- Implemented AI-augmented engineering workflows (-40-50% SDLC overhead)
- Improved system observability (-50% MTTR)
- Directed lifecycle and delivery of 7 simulation products used for system validation
- Mentored and scaled a 14-person engineering team with 0% attrition
- Built a FAISS-based RAG documentation engine to eliminate knowledge silos
- Team leadership
- Product strategy
- Platform modernization
- Observability
- AI-Native workflows
- RAG
Software Architect Alstom Transportation
- Architected a deterministic digital-twin simulator for real-time control and testing
- Designed a common software framework reducing development/maintenance effort by 30%
- Established architecture standards adopted across the simulation product line
- Evaluated and guided architectural tradeoffs (modular monolith vs. services)
- Instituted architectural governance for stakeholder alignment (RFCs / ADRs)
- Digital twins
- Real-time
- Determinism
- Tradeoff analysis
- Architectural governance
Senior Software Engineer Bombardier Transportation
- Built real-time, deterministic train positioning and motor-response simulation systems
- Designed a hardware-in-the-loop API bridging digital simulation with physical control systems
- Led architectural design and served as scrum master for simulation/test products
- Delivered technical guidance and training to engineering teams and key users
- Simulation
- CBTC
- HIL APIs
- Scrum master
- Mentorship
Education
B.S. | Computer Science Youngstown State University summa cum laude
B.E. | Electrical Engineering Youngstown State University summa cum laude
Contact
- Email available on the home page
- linkedin.com/in/stephen-ullom-7014a455
- github.com/brokhuli