Original sentence: Skylink replaced the original Airtrans system (part of which was later operated as American Airlines' TrAAin System), which was notoriously slow at a top speed of 17 mph, uni-directional (though it was a state-of-the-art automated system when the airport opened) and whose stations were outside security
Edited sentence: Skylink replaced the original  Airtrans system (part of which was later operated as American Airlines' TrAAin System), which was notoriously slow at a top speed of 17 mph, uni-directional (though it was a state-of-the-art automated system when the airport opened) and whose stations were outside security