(24-03-2010, 03:02 PM)Archie Wrote: Can somebody give me an explanation on headway, and it's meaning please?
Many thanks.
In very simple terms, it is the minimum interval that one train can follow another (at the designed speed) without the following train receiving a cuationary aspect. For mainline three aspect signalling, this means that the back of the first train must just clear the overlap of a signal before the following train reaches the sighting point of the signal that will have just stepped up from yellow to green (ie it will be a distance of [two complete signal sections plus an overlap length, plus a sighting allowance, plus a train length] behind the first train).
Given that headway calculations form a significant part of the module 2 paper, such a short explanation cannot hope to have covered everything!