Ratter, I used to carry steel a few years ago & would never ever travrel as close as those two HGVs! Why, the way that 2nd unit braked would cause the load to go straight through the Headboard ( Front ) of the trailer & taking the drivers life, I have seen this happen, there are different loads that the driver drives accordingly, Bottles on pallets would be all over the road, Timber would damage the trailer, Fluid tankers even with baffles within the tank can "push" the hgv forward, Farm animals can also "push" the HGV forward and can kill whatever animals that's inside, I am talking about experience, It's taken me near 40 years to gain experience within the Haulage industry & I think I have transported near everything that made, a computer may be good but it can not make an immediate decision like a pilot / driver, I have been in positions that require's experience eg / Fog / Ice / Snow, how can a computer decide what action to take?