Where to Spot a Train in Iowa City?

Hello,

I am taking a photography class and our next assignment is to shoot a moving object. I would like to take some photos of train engines. Can anyone recommend a good spot where I can set up my camera safely and catch a few trains go by? It needs to be a spot where I am not trespassing and where I can get a few shots at different exposures (i.e. where I have to see a few trains go by.)

The only spot I can think of is the bridge on Summit street. Let me know if you live by the tracks and you can recommend a spot and a time where it will be busiest!

Thanks!