What were/are the biggest blunders in mass transit history in your opinion? Not referring to disasters like plane crashes or ships sinking, but rather transportation that is/was just really bad or really poorly thought out awi4nitgkwffwskkieyazq. Only count things that made it into widespread public use.

Include:
-Projects that went way over budget
-Things that turned out to be bottomless money pits after completion
-Obviously bad ideas/lack of market research/lack of foresight
-Flaws in engineering due to incompetence
-Bad implementation
-Poor public reception
-Things that never came close to meeting expectations
-Anything that makes you facepalm

Don't include:
-One off prototypes
-Ideas that never saw the light of day
-Anything that was never used by the general public