This is a d3-implemented interactive model to explain technical debt
Try it here:
http://18f.github.io/d3-technical-debt/index.html
This model is implemented with D3 starting from code (http://tympanus.net/codrops/2012/08/29/multiple-area-charts-with-d3-js/)
published by Tyler Craft on CoDrops. We thank Tyler Craft starting point and CoDrops for publishing with a license that allows us to reuse their work: http://tympanus.net/codrops/licensing/