The Washington Park & Zoo Railway is a 1950s-era, 2 ft 6 in (762 mm) narrow gauge railroad designed to carry passengers on a 2-mile (3.2 km) line between the Rose Garden and the zoo. It was opened in phases from 1958 to 1960. Currently, it is partially closed because of needed maintenance on retaining walls and culverts as it runs through the woods; until that work is done, it operates only within the zoo.[20] The Portland Japanese Garden is a 9.1-acre (3.7 ha) private traditional Japanese garden that opened in 1967.