What is "tvrr"

TVRR can stand for three American railroads:

• The Tanana Valley Railroad, a narrow-gauge railroad in Alaska, operating in the early 20th century
• The Tulare Valley Railroad (its reporting mark), a small railroad network operating 1992–present in California
• The Tuscarora Valley Railroad, a narrow-gauge shortline in Pennsylvania, operating in the late 19th and early 20th centuries