We looked on the place you can find anything (photo courtesy of eBay) and there are actual old brass whistles for sale. We might buy it just so it doesn't find its way back to a real life train and toot at 530.
These whistles, by the way, have a code. We won't list them here but this is a link that will tell you all you want to ever know. The one we hear is Two long and two short (or two long, one short, one long) - and if you have read that little article at the end of the link, you'll know that it means the train is going to cross a "crossing point" and watch out; so the 4th Street crossing is the culprit.
More than a few of us wake up to this sound and there was a time more than a few were on it every morning. We didn't like catching it but we would miss it if it went away. We suppose that trains and tracks were just a part of our lives growing up as most small towns and rural communities had them in some fashion - leftovers perhaps from before endless trucks clog our roads and they were either terminus points or crossing points (meeting points or waiting points in railroad talk) and we built towns and societies around them. What journeys we missed. What greetings and waves goodbye.