I was just curious because sometimes the text gave me the feeling that all the locations on the map are quite near but on the other hand it seems to be a large area where you really have to travel from one location to the other.
In addition to that I did not wait until the Marines reach the Imperial Troop, attacked by Tyranids but just let it happen after some period of time. Thus they heard shooting and shouting and charged to the battle field. I am no friend of "it-happens-if / when-you-go-there".
And am I right that a number is wrong? I think the number belonging to the overturned crawler (I have not the book with me) is set next to the reinforved camp - which is the next map, which nix not explained at all in any detail?