Interstate 695 was planned in 1955 as an “inner belt” circumferential route in Boston and adjacent towns. When it was cancelled in 1971, construction had already begun. Rights of way that had been cleared have since been reused for roads and mass transit, but some never-used structures remain to this day, including a “ghost ramp” in Somerville that would have connected I-695 to I-93. This ramp, which is a mere stub that begins on an elevated stretch of I-93 and ends in mid-air, and which is blocked off to prevent use, constitutes technical debt in the form of incomplete implementation. Google satellite view
For safety reasons, the ghost ramp must be regularly inspected, maintained, and insured, but it provides no utility and it is not used for any civic purpose. Because the cost of retiring this technical debt — namely, demolition costs —would likely exceed the present value of the lifetime costs of inspection, maintenance, and insurance, the ghost ramp remains.
Sometimes, the best way to deal with technical debt is to leave it in place.