It's not your imagination. Almost two years ago (during August of 2006), the federal govt started requiring trains to blow their whistles louder, for four toots prior to EVERY grade-level crossing. It is now at 95 decibels.
So, yes, trains are blowing their horns louder. Some engineers lean on the horn virtually all the way through town, instead of making a few short toots at each intersection. Why? Who knows.
To put it in perspective, people who live near the airport in the Twin Cities receive roof insulation and in-home air conditioning if routine airline noise exceeds 65 decibels.
We live near the tracks and immediately noticed that train noise--which we had become accustomed to--was now waking us in the middle of the night--especially when we have the windows open.
The only solution (besides earplugs, which might keep you from hearing your alarm clock!) is to get "quiet zones" established in town, which requires the city council to put additional curb barriers in the crossings to prevent vehicles from driving around downed cross-arms. There is quite a procedure involved. They are trying to get a quiet zone in Dassel because there is quite a bit of housing along the tracks.
Another solution--not very practical--is to get the local govt. to request crossings be closed, or to install more above or below-grade crossings. That would require a big expenditure of taxpayer dollars because the railroad won't pay for it.
The increased sound level is, in my opinion, hazardous to the health of people who live near the tracks. I suppose it was required because so may people drive with loud radios, I-pods, cell phones, etc., that they were not hearing the train horns. But why should people who reside in railroad towns suffer for driver inattention--especially at crossings outfitted with automated crossing gates?? Perhaps this is another result of well-meaning, but short-sighted legislation or regulation.