IZU, Shizuoka -- A 15-inch gauge railway considered the smallest rideable train line in the world was back in operation on March 5 after a seven-month hiatus for repairs.

Volunteers acquired a 1956 15-inch gauge train, similar to ones used in amusement parks of the era. As they restored the train, they built the track over the next four years.

They settled on the 15-inch track gauge by estimating the "width of the average adult fanny multiplied by two," arriving at a scale that allows for a real railroad experience without feeling dinky.