I think this is true as it tends to win awards for safety, in most(If not all) of it's big routes in from the South, to the northeast. It tends to be the opposite for CSX strangely enough. I'm not being biased or anything I'm just looking through internet sites, etc. Here's a link below
http://www.nscorp.com/nscportal/nscorp/safety.html
http://www.nscorp.com/nscportal/nscorp/safety.html