A method of modifying a time to collision threshold includes receiving data and images of an object from image capturing devices and non-visual sensors within an automobile, from infrastructure cameras, and from image capturing devices within other automobiles, determining ambient light levels and color of the object, comparing ambient light levels to a pre-determined ambient light level threshold, determining a standard time to collision threshold, and sending the standard time to collision threshold to the collision avoidance system when ambient light levels are at least the pre-determined ambient light level, and, determining a standard time to collision threshold, a lighting coefficient, a color coefficient, applying the lighting and color coefficients to the standard time to collision threshold, calculating a modified time to collision threshold, sending the modified time to collision threshold to the collision avoidance system, when the ambient light levels are less than the pre-determined ambient light level threshold.