1.  Car will accelerate (a=gu) until it reach maximum speed under the following condition:
 there is no car in front and it can pass the next street light before light turn red.
2. Car will de-accelerate(a=-gu) until it reach zero velocity if it is too close to the car just in front of it.
 The minimum distance is related to reaction time, d[sub]min[/sub]= V * t[sub]reaction[/sub].
3. Car will keep at the same speed if it reach maximum speed.