I finished the series so though, might as well make an entry that references each for easy access.  Here's the four entries that make up the series.

1. Bus Advantages – The Work Horse of the Transit Industry
2. Light Rail Advantages – The Sexy Intermediary Between Bus & Heavy Rail
3. Heavy Passenger Rail Advantages – The King of People Moving
   
4. Streetcar Advantages – The Slick Fun Rides on the Streetcars