Thanks for the reply.As you well know, railroad photography is unforgiving. You have to envision a shot without the subject and figure through factors of safety, lighting, shutter speed, composition and when to trip the shutter. Depending on train density, there's often no second chance.
Yes! Those Brightline trains can be running up to 70MPH even in metro areas.
Usually shoot manual mode. Set exposure before arrival matrix metering (if its bright off sky). AF-C, single point (BBF) most of the time on the front using 24-120 and un-zoom and pan as it approaches trying to get several decent shots in. With the Brightline train sometimes an additional shot can be had the front and back are identical.
Also have used the single shutter trip at the composition I was hoping for, may be best option for D5100. Its interesting the thing that throws me most of my game is the feeling of power from the train (especially freight) when in close proximity.
Keep those images coming.