We have some very busy tracks coming through our town, and four crossings. The tracks are used by BNSF. There is also a private switching company, the Clopuet Transfer Railroad, which moves stuff around the wood yard (SAPPI) and processing mill as well as a couple other industries, they also do rail car maintenance.
I notice the small company often simply makes a short toot at the crossing. Thy are usually only moving about 5 or 10 MPH, pulling one to four cars. Their bell is ringing the whole time.
BNSF, however, is all over the place with their horn blowing. Some of the engineers pull long blasts for the entire 3 miles through town. Effectively waking up everyone in town. There have been several letters to the editor in our town about this, so this is not a fabircated issue.
Other operators do the 2short, 1 long, 1 short routine. I assume it is voluntary as far as how they sound the horn, although mandatory that they do it.