This is the 11412th most frequent Russian word.
длительные
Prolonged or long-lasting.
In this sentence, 'длительные' is an adjective describing trips as being prolonged or extended in duration.
Длительные поездки требуют тщательной подготовки.
Long trips require thorough preparation.
Here, 'длительными' is used to describe training sessions as being extended in time.
Он занимается длительными тренировками, чтобы улучшить свою выносливость.
He engages in long training sessions to improve his endurance.
In this example, 'длительные' is used as an adjective to characterize negotiations that took a significant amount of time.