Air Train 1.5 miles to connect La Guardia to NYC subway and LIRR. 2015 for $450 million.
https://en.wikipedia.org/wiki/AirTrain_LaGuardia
Oh wait. Scratch that. Cost overruns put it in the $2.4 billion range so far, and a total of $7 billion over 12 years to complete led to the project officially being scrapped today. March 13 2023.
https://www.nytimes.com/2023/03/13/n...-airtrain.html (paywalled, but enough there to get the gist)
Good news is this pinned thread remains as viable as ever. APC for the win.
(A real shame, NYC and LGA really could use this. Alas.)