The college should run a free bus to the grocery store every Saturday. [...] When our residence hall organized a grocery trip last month, twenty students signed up and every seat was taken. Several people said they normally ask a friend to drive them. Since the bus was full, a weekly service would reduce the number of cars on the road. It would also mean fewer students bringing cars to campus just to shop. The interest in that trip makes me think the service would be used throughout the year.
[...] The main problem is that not everyone can shop on Saturday afternoon. Some students work then or need to buy food during the week. Others might want to go to a different store. [...] The bus would not have to replace every car trip to be useful.
After a semester, the college could decide whether to add another trip. The driver could count passengers each week and ask how they would have reached the store otherwise. Those answers would help show whether the bus was replacing car trips or mostly carrying students who would not have gone shopping. If the main goal is to reduce driving, the college needs to know more than whether the seats are full.