They'd reduce traffic jams simply by behaving consistently over time. A very large number of traffic problems are caused by distracted/daydreaming drivers, aggressive drivers, overly cautious drivers over-braking, etc.
Consider the situation of lane-merging. Studies have shown a zipper-merge at the end of the disappearing lane to be the most efficient method. Yet human drivers create huge traffic snarls in these situations based almost entirely on their emotional reaction to what they perceive as 'fairness', which hinges on a thoroughly baseless concept of 'winning' in traffic.
Introduce driver-less cars and --with no other changes to traffic patterns at all-- the rising incidence of proper zipper-merging will reduce the frequency and severity of traffic problems.
Consider the situation of lane-merging. Studies have shown a zipper-merge at the end of the disappearing lane to be the most efficient method. Yet human drivers create huge traffic snarls in these situations based almost entirely on their emotional reaction to what they perceive as 'fairness', which hinges on a thoroughly baseless concept of 'winning' in traffic.
Introduce driver-less cars and --with no other changes to traffic patterns at all-- the rising incidence of proper zipper-merging will reduce the frequency and severity of traffic problems.