There are three reasons for giving serious consideration to technologi
cal countermeasures against driver fatigue: 1, fatigue is a persistent
occupational hazard for professional drivers; 2, some professional dr
ivers are under considerable pressure to reach their scheduled destina
tion, in spite of feeling drowsy; 3, fatigue adversely affects an indi
vidual's ability to assess their own fitness to continue driving. Howe
ver, there are two reasons for exercising caution in implementing tech
nological countermeasures: 1, their reliability under real traffic con
ditions is largely unproven; 2, they could be used by unscrupulous dri
vers to support the continuation of journeys that should have been ter
minated because of human impairment. This paper draws on the findings
of research into the origins, symptoms and development of human fatigu
e, and on recent research into driver support systems, to assess the p
rospects for implementations of technological countermeasures against
driver fatigue in the foreseeable future. (C) 1997 Elsevier Science Lt
d.