why do aviation experts think that the biggest risks when talkng about runway excursions are aircraft ones !. Well they are not its the amount of vehicles and drivers without proper training and technology available to them that are the biggest risk. The major airports have around 30 at any one time that are able to free range around an airfield. Carrying out various tasks.
There is technology out there and I just dont mean having transponders on vehicles which in effect only help ATC and do not stop runway incursions. And what ATC controller in their right mind would want 30 transponders from vehicles cluttering up his screen at once when he is supposed to be controlling aircraft ?
The technology involves a visual airfield map so that the driver is always aware of his position and the runways are ring-fenced so that an audible alarm goes off in the vehicle. Having experience of 25 years in Ops I have dealt with vehicles involved in runway incursions and some are from experienced staff of ground handling companies or contractors. (not airside Ops)
there is also technology with infrastructure and the way stop bars are operated. there is a currently a trial at Aberdeen with a second set of lights that will illuminate if the first set is driven over. Still technically an incursion but it stops the aircraft/vehicle from infringing the actual runway.
This I believe is all down to cost and the unwillingness of airports to have this technology in all vehicles capable oif driving on the manoeuvring area. Well one day it will come back to bite them on the backside.