The bill in favour of the Elizabeth Line was only put to parliament in 2005, receiving royal assent in 2008. Construction work began in 2009, faced some delays during COVID, but was completed in 2022 (total construction time: 13 years)

Construction on New York's Tunnel #3 began in 1970. It was 28 years before any part of it was operational. A second section came online 15 years later (2013). The final stage isn't expected to be completed until 2032, a full 62 years after construction began. I'm unaware of any comparable tunnel project which has progressed at this slow of a pace.