With the partial opening of Westside MAX in 1997, TriMet's "Type 2" light rail vehicles were introduced. The Siemens model SD660 (originally SD600, but retroactively redesignated SD660 in 1998 [ 30 ] ) have a low-floor design, a first for light rail vehicles in North America, [ 31 ] [ 32 ] digital reader boards and a slightly more open floor plan.