Nem sokat kellett keresnem:

http://trid.trb.org/view.aspx?id=59797

"In 1975 after being subjected to 250 million tons of traffic at speeds to 200 km/h, the decision was made to rehabilitate the track of the original New Tokaido Line between Tokyo and Osaka. The growing incidence of defects in rails and welds, degradation of ballast and absence of proper maintenance bases came in for attention. The scheduling and forces necessary for various phases of these programs are described. The problems which have been encountered to date and possible solutions are discussed."

Szóval 6 év alatt már voltak sín, hegesztés és ágyazathibák.

http://trid.trb.org/view/59798

"As part of the rehabilitation of the New Tokaido Line, all 123 turnouts are to be replaced by 1981 with units incorporating the heavier rails being installed throughout the route. The line is shut down entirely during periods of slack traffic for these changeouts. The procedures and equipment used to achieve the scheduled replacements are described."

1981-ig 123 kitérőt is cseréltek.