As the Seikan Tunnel, the world's longest undersea tunnel connecting two of Japan's main islands by railway, marked the 30th anniversary of its opening Tuesday, better coexistence between high-speed trains and freight is still under study.
The 53.85-kilometer tunnel connecting the northern tip of Honshu with Hokkaido, of which a 23.30-km portion runs undersea, has been serving as a major transport artery ever since its opening as it is hardly affected by weather conditions, including heavy snow in winter.
According to data by Hokkaido Railway Co., it took about 24 years and cost about 690 billion yen ($6.47 billion) to complete construction work with the involvement of some 14 million workers.
Construction of the tunnel, which runs 240 meters below the sea surface at the deepest part, was extremely difficult, with workers facing numerous problems such as frequent landslides and flooding seawater. Thirty-four workers lost their lives.
The construction project began rolling amid public outcry seeking a safer way to cross the Tsugaru Strait after a powerful typhoon sank the Toya Maru and other boats in the waters and killed over 1,100 people in September 1954.
The now-defunct Japan Railway Construction Public Corp. began boring in 1964.
(Construction in March 1985)
In December 2017, the tunnel was selected as one of 20 symbols to represent the country's technology and cultural heritage by the International Council on Monuments and Sites' national committee in Japan. ICOMOS is a UNESCO advisory panel.
The Seikan Tunnel was the world's longest railway tunnel until the opening of the Gotthard Base Tunnel in Switzerland in December 2016.
Freight trains going through the Seikan Tunnel have been mostly transporting agricultural produce from Hokkaido to other parts of the country and bringing books and processed goods to Japan's northernmost main island.
About 50 freight trains and 30 shinkansen bullet trains pass through the tunnel daily, with some 2.47 million tons of cargo, including 60 percent of the onions and 40 percent of the potatoes produced in Hokkaido, being distributed through the tunnel in fiscal 2015.
"Japan's logistics have improved significantly thanks to the Seikan Tunnel. We will make efforts so that freight trains will continue playing a significant (logistical) role," said Shuji Tamura, president of Japan Freight Railway Co.
Since the start of the Hokkaido Shinkansen bullet train service between Shin-Aomori and Shin-Hakodate-Hokuto in March 2016, the train operators have been working to find the best way for conventional freight trains and the high-speed bullet trains to share the tunnel.
Freight trains heading for Honshu must stop at Goryokaku Station in the southwestern Hokkaido city of Hakodate to switch diesel-powered locomotives to electric locomotives, capable of running under a separate voltage system, because they share a rail with the bullet trains in the tunnel and its vicinity over an 82-km stretch.
In the section, trains run on the dual-gauge tracks with freight trains and bullet trains occasionally passing each other, while a delay in freight trains will likely affect the schedule of shinkansen trains as well.
"I operate with caution in order not to cause delays or other trouble," a freight train driver said.
Another headache in sharing the railway among freight and bullet trains in the undersea tunnel is slowing the high-speed trains down.
The Hayabusa Shinkansen series, the fastest kind of train in Japan with a top speed of 320 km per hour, needs to slow down to 140 kph inside the tunnel to prevent freight trains' loads from falling due to wind pressure when they pass each other.
The speed limit in the tunnel may be raised up to 160 kph, possibly in the spring of 2019, after test runs conducted by JR Hokkaido, but it will be able to shorten the travel time between Tokyo and Shin-Hakodate-Hokuto stations, the gateway to Hokkaido and current terminus of the shinkansen line, by only three minutes from four hours and two minutes.
The Ministry of Land, Infrastructure, Transport and Tourism's council for transport policy has considered a plan to adjust freight trains' timetable so that a bullet train and a freight train would not pass each other in the tunnel. But doing so may restrict the amount of goods distributed throughout the country.
"As long as there's demand (for railway freight), it's difficult to reduce the frequency of service," a Japan Freight Railway official said.
Given that the Hokkaido Shinkansen line service is planned to be extended to Hokkaido's capital Sapporo in the spring of 2031, the significance of the Seikan Tunnel is expected to increase, and the train operators will need to do a balancing act between implementing faster passenger services and securing stable freight services.