Definition of "right away"

The locomotive was the now inevitable American 2-8-0, No. 2623. There she stood, effectively blocking the level crossing, simmering gently, massively inert. It was almost dark, and one's final sight was of her high, firelit cab, the enginemen nonchalantly leaning out, waiting for the right-away, while impatient road convoys piled up on both sides of the crossing.

1945 January and February, “Notes and News: American Locomotives in France”, in Railway Magazine, page 46