This set was the first set to debut any kind of elevated rails, so these rails are the first generation elevated rails. These rails are also included in the newer Asama Opening Commemorative Set (プラレールあさま開業記念セット), the mold was preserved properly. If you form a circle, the new elevated rails are fitting in the inner part of the older elevated rails.
One way to identify old rails: Double concave rail ends, double convex embedded pier connectors. This set lacks 1/16 short straight rails so it is definitely difficult to connect to newer rails, high manufacturing costs means only 1 year of production so there is little information on the net and the likelihood of it appearing in auctions for past 120 days is 1 out of 35 according to statistics.
One way to identify old rails: Double concave rail ends, double convex embedded pier connectors. This set lacks 1/16 short straight rails so it is definitely difficult to connect to newer rails, high manufacturing costs means only 1 year of production so there is little information on the net and the likelihood of it appearing in auctions for past 120 days is 1 out of 35 according to statistics.