Since I have a son who was crazy about trains when he was younger, I always note stories about new uses for public transportation. Here is an interesting story from Massive Science that describes an new initiative by Salt Lake City to measure air pollution across the city by putting sensors on their TRAX light rail as it moves back and forth across the city. This allows them to monitor where the pollution is coming from and how it is changing over time due to weather variations, time of day, and other factors. You can read more here.
