JNR at that time was also performing speed tests at a speed of more than 120 km/h on electric trains and electric locomotives, but these tests were performed under conditions almost equal to those of commercial operation, and moreover, Kansai private railroad companies including the Hanwa Electric Railway and New Keihan Railway, which adopted the newest Western electric railroad technology, were known to have constantly been performing high speed driving at 120 km/h during the prewar period on their commercial trains (without filing, knowing that the Ministry of Railways would not permit speeds over maximum driving speed of JNR), which made it clear that the Japanese railroad technology, especially that of steam locomotive designing was lagging behind.
同時期の国鉄では、電車や電気機関車でも120km/h超過の速度試験が行われていたが、こちらは営業運転とほぼ同等の条件で実施され、また欧米系の最新電気鉄道技術を採用した阪和電気鉄道や新京阪鉄道といった関西私鉄では、戦前の段階で既に120km/h超の高速運転が営業列車で恒常的に（それも鉄道省が国鉄の最高運転速度以上の速度を認可しないことを見越して、届けを出さないままに）実施されていたことが知られており、日本の鉄道技術、ことに蒸気機関車設計技術の立ち遅れは明白であった。