The Analog Incident Story Trainyard Lantern Map: Designing a Tabletop Paper Network That Reveals Hidden Reliability Blind Spots

Digital systems are abstract, invisible, and sprawling. When they fail, they fail in ways that are hard to picture and even harder to explain to people outside the immediate team. Dashboards, graphs, and runbooks help, but they often reinforce existing mental models instead of challenging them.

This is where analog tools can do something surprisingly powerful. In this post, we’ll explore the idea of an “Incident Story Trainyard Lantern Map”—a tabletop, paper-based, Reliability Block Diagram-inspired map of your systems that illuminates the hidden blind spots in your reliability thinking.

We’ll connect a few key practices:

• Reliability Block Diagrams (RBDs) for modeling how systems actually stay up (or go down).
• Incident reviews / postmortems for extracting patterns from outages instead of just patching symptoms.
• Dependency mapping for surfacing the components and packages you didn’t even realize you rely on.
• Analog, tactile visualizations that create shared understanding across engineers, managers, and adjacent stakeholders.

The result: a living, physical map that turns incidents into lanterns highlighting where your reliability assumptions don’t match reality.

From Reliability Block Diagrams to Story Maps

Reliability Block Diagrams (RBDs) are a classic tool from reliability engineering and safety-critical domains. They model a system as a network of blocks and connectors, where each block represents a component (a service, database, API, or even a person or process), and the connections represent how those components combine to deliver an outcome.

At the simplest level:

• Series components: All must work for the system to work. One failure = total failure.
• Parallel components: Only one needs to work. This implements redundancy.

RBDs shine because they:

• Force you to be explicit about dependencies.
• Make it easy to ask “what if this fails?” in many scenarios.
• Help you prioritize where to add redundancy or invest in hardening.

But in fast-moving software organizations, RBDs often live as static diagrams on Confluence or in a modeling tool that only a few specialists open. They’re powerful—but not often social.

The Incident Story Trainyard Lantern Map takes the spirit of RBDs and turns it into a shared, analog artifact laid out on a table, wall, or whiteboard that everyone can gather around and modify together.

Why Map Incidents on Paper at All?

Teams already have Jira tickets, incident timelines, and architecture diagrams. Why add paper to the mix?

1. Analog maps slow the thinking down—productively.
A physical map forces you to step out of autopilot. You can’t just scroll past a subtle dependency or group of microservices. You have to place them, connect them, and look at them from a distance.

2. They create a shared language across roles.
Engineers, SREs, PMs, and even execs can all point to the same shapes and arrows. Complex reliability conversations become more like looking at a subway map: “Here’s the main trunk line; here’s the fragile branch; here’s where we had the delay.”

3. They surface “shadow dependencies” and hidden components.
When you physically map the path of an incident from user action to failure, you bump into:

• Third-party APIs you forgot were critical.
• Shared libraries and packages that many services rely on.
• One-off scripts or cron jobs no one really owns.

These are classic reliability blind spots that digital diagrams often gloss over.

4. They complement, not replace, digital tools.
The point isn’t to abandon your service catalog or observability platform. It’s to create a bridging artifact that helps different perspectives meet in the middle and then feed discoveries back into your systems.

The Trainyard Metaphor: Blocks, Tracks, and Switches

Picture your system as a trainyard:

• Trains = user journeys or key workflows (e.g., “checkout,” “signup,” “data export”).
• Tracks = dependency paths through your services, databases, and third-party integrations.
• Switches = decision points, feature flags, or failover mechanisms.
• Yard sections = subsystems or domains (payments, auth, analytics, etc.).

An RBD fits naturally into this metaphor:

• Series blocks become single-track segments: if any segment fails, the train can’t pass.
• Parallel blocks look like branched lines: trains can reroute if one track is blocked.

Now add the “lantern” aspect: each incident you review becomes a lantern hung over the part of the yard where something went wrong, dimly exposing other parts that might also be vulnerable.

How to Build an Incident Story Trainyard Lantern Map

You don’t need special tools. Start with:

• A large sheet of paper, whiteboard, or pinboard.
• Sticky notes in multiple colors.
• Markers, tape, and string or yarn.

1. Choose a Critical Workflow

Pick a single, high-value workflow such as:

• User sign-up
• Checkout & payment
• Data ingestion pipeline
• Report generation

This is your main rail line. Draw a starting point and an end point.

2. Map the Dependency Tree (Not Just the Architecture)

For each step in the workflow, ask:

"What must succeed here for the user to get what they expect?"

Add blocks (sticky notes) for:

• Internal services and microservices
• Databases and queues
• Caches and storage layers
• Third-party APIs or SaaS tools
• Shared packages or libraries
• Configuration, feature flags, or scheduled tasks

Draw lines to connect them in series (must succeed together) or parallel (redundancy / fallback).

You’re effectively building a reliability block diagram on paper, tuned to one user journey.

3. Layer in Real Incidents as Stories

Now bring in your incident reviews / postmortems.

For a given incident:

1. Mark the components that were directly involved with a bold border or a specific color sticky.
2. Annotate the path of the incident like a story:
   • Where did the symptom first appear?
   • Which component actually failed first?
   • What made the impact bigger or smaller?
3. Note contributing factors on small stickies or flags:
   • “Alert didn’t fire”
   • “Runbook outdated”
   • “Hidden coupling to billing service”

You’ve now turned a linear incident timeline into a spatial narrative anchored in your dependency network.

4. Use “Lanterns” to Highlight Reliability Blind Spots

For each incident, add a lantern marker (e.g., a yellow circle or special sticky) at the root cause or key amplification point. Then ask:

• What other trains (workflows) pass through this same track?
• Which nearby blocks share this component, library, or configuration?
• Is this block implicitly treated as “always up” in our mental model?

When you repeat this over multiple incidents, patterns emerge:

• A third-party provider that appears in many workflows but rarely in official diagrams.
• A shared “auth helper” package that nobody truly owns but everyone depends on.
• A “reliable” database that actually has a single-point-of-failure configuration.

Those lantern clusters are your reliability blind spots made visible.

Turning Visuals into Action: Prioritizing Reliability Work

Paper maps are only useful if they change what you do next.

Once you’ve layered incidents onto your RBD-style trainyard, step back and:

1. Identify the most critical blocks.
Look for components that are:

• On the path of many key workflows
• Regularly touched by incidents
• Single-point-of-failure in a series chain

Those are your high-leverage reliability investments: add redundancy, improve failover, or strengthen SLOs and alerting.

2. Decide where to add parallel tracks.
Where a single component is carrying disproportionate risk, design and mark potential parallel paths:

• Alternate data stores
• Backup providers
• Cached or degraded modes

Then feed those ideas back into your architecture and roadmaps.

3. Improve observability where the map is “foggy.”
If there are parts of the map that feel hand-wavy—“something something ETL script over here”—that’s a sign you need:

• Better ownership and documentation
• More instrumentation and metrics
• Clearer incident runbooks

The analog map reveals not just technical weaknesses, but gaps in shared understanding.

Building a Feedback Loop: Incidents → Map → Design → Incidents

The real power comes when you use the map not as a one-off workshop artifact, but as a living feedback loop tying together:

1. Structured modeling (RBDs / dependency trees).
   These give you a principled way to understand how failures propagate and where redundancy helps most.

2. Disciplined incident reviews.
   Postmortems aren’t just storytime; they’re inputs that update the map:

   • New blocks added
   • New connections discovered
   • New lanterns revealing patterns

3. Iterative design and prioritization.
   The clusters of lanterns and critical series paths influence:

   • Reliability roadmaps
   • SLOs and error budget policies
   • “Day 2” engineering priorities

Over time, you should see the map change shape:

• Former single-track segments gain redundant paths.
• High-risk lantern clusters shrink as mitigations land.
• New blind spots occasionally appear—but in a context where you’re already used to finding and fixing them.

This is how you move from reactive firefighting to a culture of systematic reliability improvement.

Conclusion: Make Reliability Visible, Together

Complex systems fail in complex ways. Tools like Reliability Block Diagrams and incident reviews give you structure and data—but they can still leave critical dependencies hidden in plain sight.

By building an Incident Story Trainyard Lantern Map—a tangible, tabletop paper network of your systems and their failures—you:

• Transform scattered incident knowledge into a shared, visual narrative.
• Expose hidden components, packages, and third-party services that quietly hold enormous risk.
• Give teams a common artifact for prioritizing reliability work where it matters most.

Most importantly, you create a continuous feedback loop: incidents illuminate new parts of the yard; the map guides design and prioritization; and improved systems feed back into fewer, clearer, more instructive incidents.

You don’t need fancy tools to start. Just a big sheet of paper, sticky notes, and the willingness to put your assumptions on the table—literally. The blind spots are already there. The map just helps you see them, together.