The integral calculus formuln of physical quantity of traffic flow system is obtained. The first derivative of physical quantity of the system with respect to time equals the partial derivative of physical quantity of control field to time plus clear flux of physical quantity passing the control line in unit time. According to the law of conservation of mo mentum, traffic momentum cpuation in integral ealculus form is obtained. The rate of the momenturn change of the systcm is balanced by the force acting on this system. The rate of the momentum change in contro...
