"Boston Common shuttles. The efficiency is amazing. School buses line the entire length of Boston Common along Tremont Street, and a volunteer waves a flag when a bus is full. They all pull away and another wave comes through immediately. It took me about 20 minutes to get on the bus. (Another helpful expo tip: Don't drink a lot of coffee because there's a wait to get on the bus and about a 30-minute ride to Hopkinton.)"