Although the ability to designate pattern violators has been on the books since 1977, Main said it wasn't used until 2010, after 29 miners died in an explosion at Massey Energy's Upper Big Branch mine in southern West Virginia.That year, MSHA identified 53 mines for review, labeled 17 potential violators and put two on the POV list. In 2011, MSHA screened 39 mines and put eight on the POV list. Last year, MSHA looked at 20 mines and issued four potential pattern violator notices. The fact that fewer mines are being identified as problematic "clearly is indicating that we're reducing the number of chronic violators," Main said. "We believe this process is working to make mines safer." Tram Energy's mine was cited for 120 serious violations during the review period, more than half of which involved operator negligence, MSHA said. The agency shut down the mine 40 times during the year. Tram Energy has been fined more than $170,000 since 2012; all but $666 of that remains unpaid, MSHA said. Tram Energy has no phone listing, and the number for its controller, Jason D. Ousley, has been disconnected. Brody Mining, a subsidiary of St. Louis-based Patriot Coal, received 253 serious violations during the review period. MSHA found that worker injuries translated to 1,757 lost work days at the mine a¿¿ 367 of which were from eight injuries the company failed to report. Patriot spokeswoman Janine Orf didn't immediately comment.