Caltrain’s troubled positive train control solution, known as CBOSS, has now been completely abandoned, to be replaced by the de-facto standard freight PTC technology known as I-ETMS. That’s mostly good news, since Caltrain will no longer be stranded with a globally unique PTC system. I-ETMS is being deployed by numerous other commuter rail operators in the U.S., allowing some economies of scale and standardization.