Qualitative change of traffic flow induced by driver response

Microscopic dynamic properties of traffic flow are studied from the aspects of both individual vehicle behavior and driver operation. We measured the time series of single-vehicle data in urban traffic and determined the nature of fluctuations around the nonequilibrium phase transition of local vehicular traffic. The probability-density function calculated from the time series of variation of velocity is transformed around the phase transition, where a Gaussian distribution changes to a Levy stable symmetrical distribution. By analyzing the microscopic dynamic processes of traffic flow in the critical region in connection with a discrete stochastic process involving random amplification with additive external noise, we found the relation between the driver´s response to perceptual quantities and a power-law probability density distribution. The empirical data of deceleration in a car-following situation obtained from driving simulator experiments indicated a large dispersion of perceptual quantities about the relations with a preceding vehicle during operation of the brake pedal. These results suggesMicroscopic dynamic properties of traffic flow are studied from the aspects of both individual vehicle behavior and driver operation. We measured the time series of single-vehicle data in urban traffic and determined the nature of fluctuations around the nonequilibrium phase transition of local vehicular traffic. The probability-density function calculated from the time series of variation of velocity is transformed around the phase transition, where a Gaussian distribution changes to a Levy stable symmetrical distribution. By analyzing the microscopic dynamic processes of traffic flow in the critical region in connection with a discrete stochastic process involving random amplification with additive external noise, we found the relation between the driver´s response to perceptual quantities and a power-law probability density distribution. The empirical data of decele- - ration in a car-following situation obtained from driving simulator experiments indicated a large dispersion of perceptual quantities about the relations with a preceding vehicle during operation of the brake pedal. These results suggest that brake pedal operation is closely related to the random amplification in a discrete stochastic process that exhibits a power-law probability density distribution of the variation of velocity.t that brake pedal operation is closely related to the random amplification in a discrete stochastic process that exhibits a power-law probability density distribution of the variation of velocity.