I don't know whether this has been shown in the USA or not. It has 2 series of 6 episodes. The first one is about a passenger plane that crashes halfway between JFK and London into the Atlantic. The storyline is very similar to the Malaysian Airlines plane that disappeared into the Indian Ocean back in 2014 I think it was.
Anyway, the second series is about a high-speed train crash travelling from Toronto to Chicago again in 6 episodes. Here is a brief description.
The plot featured an investigation of the crash of an automated high-speed train travelling to Chicago from Toronto. The accident leaves multiple deaths in its wake and a web of potential suspects which include, in addition to possible mechanical or software errors, the tech visionary who invented the train's control system; an anti-technology politician, and an FBI prisoner who disappears after the crash. When the feds swoop in to initiate a manhunt, Kendra's investigation evolves from finding the causes of the crash to working with federal agents to capture the fugitive.[2]
https://en.wikipedia.org/wiki/Departure_(TV_series)