First, lets correct your concept. Momentum is still conserved in the system. the ball is falling towards th earth and the earth is also accelerating towards the ball. the forces betwwen the earth and the ball are the same by Newton's third law. but the rate of acceleration of the earth is neglectable seemingly to have no momentum, beacuse the earth has higher mass than the ball by F=ma. Therefore momentum is still conserved.
Maintain adequate space to maneuver the direction of the car from the vehicle at the just front.
When driving in traffic it is an added advantage to the driver if the driver has an estimate of the turning radius of his/her vehicle so that he/she maintains a distance accordingly one can escape from the traffic-jam.
However is must be done with the utmost care by having a view of the situation of the traffic behind the driver to avoid any sort of accident. One should be alert and have an eye on the rear-view mirror keeping in mind that the objects appearing in the mirror are nearer on the ground than it appears in the image.