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?