Is American highways worth of the lives killed and damaged by accidents?

How should we calculate the values of life and compare it with other things? Are three lives more precious than two? I always feel wordless when people raise the question about if some act is worth of the life cost. If we agree life is priceless, that is to say from math point of view: life value -->infinite, 2*life value=3*life value. unless you give every deferent life a different kind of infinity, then if the same kind of infinite number is assigned to life, the equation still holds. It may be indeterminate in math, but in this case, if it goes beyond any affordable amount, it is the same. Then we have to say some people are more precious than others.