From a very good Wired article
Komanoff found that every car entering the CBD causes an average of 3.23 person-hours of delays. Multiply that by $39.53—a weighted average of vehicles’ time value within and outside the CBD—and it turns out that the average weekday vehicle journey costs other New Yorkers $128 in lost time.
He translates all traffic impacts—delays, collisions, injuries, air pollution—into dollars and cents; that way, it’s easy for users to compare the benefits and costs of different plans. He has even come up with a plan of his own that would, according to his calculations, collect $1.3 billion in motorist tolls per year—all of which would be spent on improving public transit—and save $2.5 billion in time costs by reducing delays. To that, add $190 million from decreased mortality as a result of making streets more bicycle- and pedestrian-friendly, $83 million in collision damage reduction, and $34 million in lower CO2 emissions.
he produced a detailed statistical analysis of pedestrian and cyclist deaths—it showed that casualties are not random, unpredictable accidents but the foreseeable result of given traffic conditions.