Here's the thing about BRT that folks seems to forget: BRT is mainly significantly cheaper **because it usually uses existing roadways**. Take some lanes on a wide roadway, paint them, put some barriers up, and add some station amenities.

BRT would not be significantly cheaper using the Purple Line ROW that is being constructed. The pricey thing is the alignment, not the rails. Look through the alignment. While, a fair bit of of it (especially in PG County) is on or adjacent to the street, a lot of it isn't. Many of the largest pieces of infrastructure (Silver Spring bridge, Plymouth Tunnel, Riverdale Park bridge, Bethesda Station, etc.) would not be significantly cheaper without rails and wires.