My favorite metaphor: bridge and road maintenance. Every now and then you have to fix potholes and repaint the bridge. Sometimes in order to do this you have to close some lanes to traffic. If you don't do this, you will accrue more and more potholes, and the bridge will start to rust. The longer this goes on, the harder it becomes to fix. If you ignore the problem long enough, the bridge will collapse one day with very little warning.
I think that metaphor is not very apt, because it doesn't capture the drag on future work. Bridges and roads are stationary.
This is why I don't like this kind of metaphor, and I don't like the Technical Debt metaphor. Because it doesn't convey the right concept. It conceals, obfuscates actual truths.
- Bad code
- Bad decisions
- Bad design
- Lack of maintenance
- Lack of proper business concept understanding
Those things mean something, you can make them more precise, but they could be actionable. Technical debt always needs a follow up question: so what is actually going on?
I use the example of publics works projects in San Francisco. There's a road called Van Ness that is going to have a bus rapid transit lane running down the middle of it. Should be really easy to do. But it's been about a decade and they're just hitting the last steps now. Why? Well, they needed to also upgrade the utilities below. But when they dug they found layer after layer of abandoned utilities, undocumented utilities, etc. So what should have been a simple operation dragged out for years because each action revealed something new.
The city now wants to add bike lanes to Market Street and is anticipating the same issues.
> I think that metaphor is not very apt, because it doesn't capture the drag on future work. Bridges and roads are stationary.
Poorly maintained roads and bridges ARE obviously a drag on future work, since nearly all other work depends on them for transportation, it drives up costs (eg. potholes start to drive up maintenance costs for vehicles and increase commute times), and reduces tax revenues (whether it is through depressing real estate prices or other mechanisms).
To say nothing of the fact that it is much more likely to fail when it is under load, so it's not just a question of replacing the bridge, but also the likely loss of vehicles and possibly lives.
Additionally, proper maintenance (or its analog to other disciplines) will usually identify when it's time to do a full replacement. Which is much better than finding out by way of catastrophe.
I wonder if this is an area where, if you can get the initial agreement, a special tax district or some kind of cooperative with dues makes sense. That way the bridge stays maintained.
The I-35W bridge collapse in Minneapolis is the perfect example of this. A contributing factor in the collapse was the weight of the maintenance equipment they had on the bridge at the time.
