Two recent changes in the transportation field may have a profound effect on traffic assignment techniques. The first is the increasing importance of environmental objectives, such as reducing air pollution, within the policies of traffic system authorities. The second change is the advent of the intelligent vehicle-highway system (IVHS), which, among other attributes, has the potential to be used to implement new methods of controlling vehicular emissions. The fact that historic traffic assignment techniques may be inadequate for modeling the traffic systems that will operate under IVHS with environmental objectives--primarily when the traffic follows routes that are based on equitable rather than equilibrium or optimal considerations--is illustrated. Then it is shown that when IVHS policies that attempt to reduce system travel time are implemented, other objectives such as reducing environmental pollution may actually increase. A network from Ottawa, Ontario, Canada, is used as a test bed.