A train travels a total distance \(L\) between two stations, starting and ending at rest. The trip consists of three phases: first, the train accelerates from rest with a constant acceleration of magnitude \(a\); second, it maintains the resulting maximum speed \(v\); and third, it decelerates to a stop with a constant acceleration of magnitude \(a\). The total distance the train travels while its speed is changing is equal to the distance it travels at a constant speed.

Which of the following expressions correctly represents the total time of the trip?