A quasi-experimental study was conducted to assess the effects of routine exposure to traffic congestion on the mood, physiology, and task performance of automobile commuters. Traffic congestion was conceptualized as an environmental stressor which impedes one's movement between two or more points. Industrial employees were assigned to low, medium, or high impedance groups on the basis of the distance and duration of their commute and were classified as either Type A or Type B on a measure of coronary prone behavior. As expected, subjective reports of traffic congestion and annoyance were greater among high and medium impedance commuters than among low impedance individuals. Also, commuting distance, commuting time, travel speed, and number of months on route were significantly correlated with systolic and diastolic blood pressure. Contrary to prediction, medium impedance As and high impedance Bs exhibited the highest levels of systolic blood pressure and the lowest levels of frustration tolerance among all experimental groups. The results were discussed in terms of the degree of congruity between commuters' expectancies and experiences of travel constraints.

A quasi-experimental study was conducted to assess the effects of routine exposure to traffic congestion on the mood, physiology, and task performance of automobile commuters.Traffic congestion was conceptualized as an environmental stressor that impedes one's movement between two or more points.Sixty-one male and 39 female industrial employees were assigned to low-, medium-, or high-impedance groups on the basis of the distance and duration of their commute and were classified as either Type A or Type B on a measure of coronary-prone behavior.As expected, subjective reports of traffic congestion and annoyance were greater among high-and medium-impedance commuters than among low-impedance individuals.Also, commuting distance, commuting time, travel speed, and number of months enroute were significantly correlated with systolic and diastolic blood pressure.Contrary to prediction, mediumimpedance As and high-impedance Bs exhibited the highest levels of systolic blood pressure and the lowest levels of frustration tolerance among all experimental groups.The results were discussed in terms of the degree of congruity between commuters' expectancies and experiences of travel constraints.In recent years, behavioral scientists have devoted increasing attention to the urban environment and its impact on people (Fischer, 1976;Glass & Singer, 1972;Michelson, 1976;Milgram, 1970; Proshansky, Ittelson, & Rivlin, 1976).A sizable body of research now exists on the behavioral and health consequences of exposure to numerous urban settings, including high-rise apartment buildings