On the other hand, as the JR companies have increased the train speeds aggressively after their inauguration, various problems have arisen, such as noise generated from contact between the power collectors and the aerial power supply lines, noise due to wind generated by the fast-moving train-car bodies, and considerable attrition of the portions in contact.
一方で、JR発足以降積極的に行われた高速化に伴い、走行中の集電装置と架線の接触や風切り音による騒音の発生や、接触部の著しい消耗などが問題とされた。