Complex sentence: Dedicated railway lines to airports have become popular since the 1980s, with airport terminals for airport express, intercity and commuter trains, allowing direct travel to the check-in halls.
Split into simpler sentences: Dedicated railway lines to airports have become popular since the 1980s. In many cases, there are stations at the airport terminal (s) for express, intercity and commuter trains, allowing direct travel to the check-in halls.