On 18 January 2026, a passenger train derailed near Adamuz, in Córdoba. 46 people died. Investigators' main hypothesis points to the rupture of a weld between two sections of track of different ages: one manufactured in 1989 and another recent one, with different degrees of hardness.
No one made a deliberate decision to build a dangerous infrastructure. What happened was more insidious: the quiet build-up of stress at a fragile junction, invisible to daily traffic, until one more train passed over it and the structure gave way. And most disturbingly: a significant anomaly—a voltage drop in the track circuit— had been registered some 22 hours before the accident.
Technical debt works in exactly the same way. It's not a bug that crashes the system outright: it's the accumulation of hastily made decisions – a quick fix here, an outdated dependency there, a module coupled to another because «it works for now» – that gradually weaken the structure beneath the surface. The system keeps running. The tests pass. Nobody sees the problem. Until a seemingly minor change makes everything collapse. And, almost always, the warning signs were there long before anyone read them.
Understanding technical debt from this perspective changes how it's managed: not as a matter of code clean-up, but as an operational risk with real consequences for deadlines, costs, stability, and the business's capacity for growth.
What is technical debt and how is it generated?
Technical debt arises when a technological solution is built with shortcuts, limitations, or decisions that make it easier to progress today, but complicate maintaining, scaling, or evolving the product tomorrow. It doesn't always stem from bad practice; sometimes it emerges from a reasonable decision within a context of limited time, early validation, or market pressure. The problem begins when that provisional decision becomes permanent. Development intended for a rapid release can remain in production for years; a temporary integration can end up being a central part of the system.
It is worth distinguishing between two types. Deliberate debt arises when a team consciously decides to take a shortcut to meet a deadline or validate a hypothesis. Accidental debt arises from ignorance, unsound architectural decisions, or a lack of quality practices. In both cases, if not managed, the result is the same: reduced speed of change, increased maintenance costs, and, eventually, in critical systems, a catastrophe.
Its most common causes are:
- Absolute priority on speed and cost control, making the exception the norm: MVPs that remain for too long without structural review.
- Lack of shared technical criteria: without common conventions or architectural vision, the system's foundation becomes irregular and difficult to maintain.
- Insufficient testing: when tests are scarce or manual, any change is perceived as a threat and the team proceeds with more caution.
- Architectural decisions that no longer fit: what works with a small team may stop doing so when the system grows.
- Roadmaps with no room for maintenance: if all the time is dedicated to new features, debt continues to accumulate, even if the team is competent.
Signs a company is accumulating technical debt
Technical debt rarely presents itself explicitly. It's usually detected through symptoms. The clearest one is that similar tasks take longer and longer: changes that used to be resolved in days now require weeks because the system demands more validation or more corrections. Another sign is the increase in recurring incidents – not just new errors, but problems that reappear or areas of the system that inspire fear when touched., Just like the section of track all drivers notice but no one formally reports.
Other common indicators include excessive dependence on specific individuals – if only one or two people know how a critical module works, the knowledge is not scaled – and difficulty in estimating, because the system's behaviour is increasingly unpredictable. The greater the technical debt, the more frequent surprises are during development.
How does it impact the business
Financial impact
The initial impact is direct: more hours to do the same thing. If implementing a functionality requires navigating a fragile system, reviewing more dependencies, and correcting side effects, the development cost rises. Not because the team works inefficiently, but because the technical environment penalises any change. Added to this is the opportunity cost: every week invested in resolving internal friction is a week not spent improving the product or reducing time to market. Delaying structural decisions for too long can also make future modernisation more expensive, turning what could have been corrected with gradual refactoring into complex and costly migrations.
Organisational and competitive impact
Technical debt deteriorates coordination between departments: sales, operations, security… When this pattern repeats, friction stops being sporadic and becomes part of normal operations. At the team level, continuously working in a fragile environment affects motivation: more energy is spent containing problems than developing meaningful solutions.
In markets where learning speed matters, technical debt can slow up responsiveness: taking longer to release improvements, adapt processes, or experiment with new products. When it also affects availability or stability, reputation and legal obligations come into play. Repeated incidents and failures at critical moments have commercial consequences., civil liabilities and sometimes, penalties; even if the origin lies in decisions made years ago.
How to approach your management
Managing technical debt doesn't mean stopping the product for months to redo everything. The process starts with four actions:
- Make it visible: identify the main friction points and translate them into impact. Does it cause delays? Does it increase incidents? Does it block new features? This translation is key to moving the conversation beyond the purely technical.
- Prioritise by value and risk: cross reference usage frequency, operational risk, and impact on future deliveries. If a component is touched frequently, fails easily, and delays strategic work, its priority is high.
- Booking capacity on the roadmap: technical debt won't be resolved if it relies on occasional gaps. It requires planned time, with improvement goals treated as part of normal product work.
- Reinforcing quality practices: code reviews, automated testing, dependency updates, and more explicit architectural decisions help prevent debt from continuing to grow at the same rate.
When these metrics—lead time, deployment frequency, incident rate, time spent on maintenance—are shared across the organisation, the conversation changes. Technical debt stops being perceived as an internal complaint and starts to be seen as a variable affecting cost, capacity, and risk. Just like a track circuit anomaly: irrelevant until contextualised, urgent as soon as you understand what it can cause.
Technical debt as a strategic variable
Understanding technical debt requires looking beyond the code. It’s a signal of how systems are designed, how technical decisions are prioritised, and how the balance is struck between today’s speed and tomorrow’s sustainability. In environments where software is the bedrock of the business, ignoring it doesn’t make it disappear: it makes it grow.
The Adamuz train gave 22 hours' notice. Software systems also give notice, almost always, before they break down.
