One goes up and down one goes side to side. Sorry been one of those days. Are you perhaps meaning the difference between a Fall Arrest Lanyard which would tend to be fastened above you such that if you fell you would be suspended from the lanyard, and a Work Positioning or Fall Restraint lanyard which would be of such a length and attached in such a way so as to stop you falling over the edge in the first place, as such these tend to run in the horizontal plane. Not sure if that's what you meant and hope it helps.

A fall arrest lanyard is typically used in the vertical plane. It is usually "flat" in section and is folded back on itself two to three times at one end (usually to a length of about 300mm. The folds are stitched together. If someone falls whist attached to this type of device the stitching is designed to "tear apart" at the end of the fall, and increasing the length of the lanyard by about 900mm. The tearing process acts as a shock absorber so that there is no sudden "shock load" on the person attached to the fall arrest lanyard (typically wearing a full safety harness). Without such a shock absorber, you can imagine the consequences! A horizontal restraint lanyard is typically a length of rope with a shackle at each end: it stops a person attached to it from moving away from the anchor point.

Guys Just reading through this discussion out of interest as I was hoping this might cover something I have come across at work. I have found a horizontal safety line which is situated around the 1 meter mark (just above waist level on a roof, to the edge of the roof (all the way along). At first glance it looks like a barrier all the way along the edge of the roof edge without a mid rail. I am hoping this is a decent enough description. My question is, has anyone come across this before or, have any idea of how this system is intended to be used? My initial gut feeling is it not been situated correctly and inadequate for use. The line has been certified for use which baffles me. Any info on this would be appreciated..........

I'm not entirely sure what you mean but assume the line is at the edge of the roof. If its meant to be a barrier it isn't suitable without the mid rail and the flexibility raises issues. In this position it's a bit pointless if intended as an anchor for a work restraint lanyard, which leaves an anchor for fall arrest. Again I wouldn't be sure what the point would be of this as it would be better to prevent the fall in the first place. Also a fall generates a lot of force even with the energy absorbing element (compared to work restraint) so I would want to see engineers design, commissioning and inspection data before allowing use (as anything)