Before the Rail Safety Act became law in 2008, Congress' original intent was to exempt all Class II and Class III railroads from positive train control (PTC) requirements. But as it turned out, the law didn't exclude regionals and short lines from the PTC mandate. The American Short Line and Regional Railroad Association estimates that Class I equipment requirements associated with their PTC implementation plans will impact up to 110 short lines. To learn more about the mandate's effects on small railroads, including some details on the Alaska Railroad Corp.'s PTC pursuit, follow this link to read an article I wrote for our December issue.