30 years on, world's longest undersea tunnel faces challenges as Japan balances bullet trains with freight www.japantimes.co.jp

The tunnel was the world’s longest railway tunnel until the opening of the Gotthard Base Tunnel in Switzerland in December 2016.
We will make efforts so that freight trains will continue playing a significant (logistical) role,” said Shuji Tamura, president of Japan Freight Railway Co.
In that section, trains run on dual-gauge tracks, with freight trains and bullet trains occasionally passing each other.
The Ministry of Land, Infrastructure, Transport and Tourism’s council for transport policy has considered a plan to adjust freight train timetables so that bullet trains and freight trains don’t pass each other in the tunnel.
“As long as there’s demand (for rail freight), it’s difficult to reduce the frequency of service,” a Japan Freight Railway official said.