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R-04 Large Curve Rail

The large curve rail (大曲線レール) is somewhat of an odd holdover from an earlier period in Plarail's development that follows the dimensions set out for two parallel curved tracks at the width formed by an older style of turnout rail used in the 1960s. The radius of these curves is around 305mm, slightly under the outer radius of double track outer curves, meaning a circle of the rails will not properly surround a circle of double rail curves. The large curve rail was given the designation R-04 under the 1987 numbering scheme and remained in the lineup until around 1997 as an individual four pack. The 1992 Thomas the Tank Engine Set was the last set to use these curves.

Smooth rails (1970-1974)

The earliest large curve rails date back to the all-smooth era of rails and seem to have first gone on sale around 1970. These rails have two circular molding marks offset from the middle of the top of the rail and smaller circular marks on the bottom of the rails. Mold numbers are located near the outboard connectors.

Roughtop rails (1974-1990)

Around 1974 rails transitioned to "roughtop" rails to increase traction of locomotives. Early roughtop examples of the large curve rail have molding numbers but no Japan markings. The circular molding marks on the top of the rail became more pronounced pips with a ring around them and tube supports were added to the bottom of the rails.


Later, "JAPAN" was added to the molding near the outboard connector. This version of the rail exists in both orientations of "up."

Treaded rails (1990s)

When the molding was moved to Thailand in the early 1990s the roughtop surface was updated with treads. This version of the rail was available individually and in the 1992 Thomas the Tank Engine Set. The molding now says made in Thailand near the molding number near the inboard connector.

After being discontinued in 1997, the Double Track Straight Rail, which had been out of print as a single item since the mid 1970s, began using the R-04 designation.