The recent decision by the Liberal Democratic Party-Komeito ruling coalition on the route for extending the Hokuriku Shinkansen superexpress train service that will eventually connect Tokyo and Osaka via the Sea of Japan coast — with the final section to be completed three decades from now at the earliest at an expense of more than ¥2 trillion — should be flexibly reviewed by comparing its benefits, cost advantage and environmental impact against alternate plans.

After the 222-km Tokyo-Nagano section of the Hokuriku Shinkansen Line opened in 1997, its 228-km Nagano-Kanazawa section began operations in March 2015, with the fastest service linking Tokyo and the capital of Ishikawa Prefecture in two hours and 28 minutes. Currently, the 125-km section from Kanazawa to Tsuruga, Fukui Prefecture, is under construction and scheduled to go into service in 2023.

The decision last week concerned choosing the route linking Tsuruga with Shin-Osaka via Kyoto out of three options. One runs from Tsuruga to Maibara, Shiga Prefecture, where it will connect to the existing Tokaido Shinkansen Line. The second route reaches Kyoto and Shin-Osaka via Obama, a Fukui city on the Sea of Japan coast. The third goes by way of Obama and Maizuru, Kyoto Prefecture. Both the second and third routes envisaged building a new bullet-train line linking Kyoto and Shin-Osaka stations. The coalition team picked the Obama route, although it left the decision on where the new section from Kyoto to Shin-Osaka will run — either south or north of the Tokaido Shinkansen Line — till the end of March.

The choice of the Obama route was made mainly on the grounds of its estimated travel fare and time — that it will be the cheapest and fastest route linking Tsuruga and Shin-Osaka. Still, a comparison of the three routes in terms of total benefits, such as economic benefits, against overall costs, including construction, operation and maintenance expenses, ranks the Obama route as second best — with its benefits barely exceeding the costs —and far trailing the Maibara route, which is estimated to bring benefits worth more than double the cost. Still, the LDP-Komeito coalition dropped the Maibara option since JR Tokai, operator of the Tokaido Shinkansen Line, pointed out that it will be difficult to let Hokuriku Shinkansen Line trains run straight into the line from Maibara due to the already tight service schedule on the line.

The problem with the Obama route is its estimated cost of construction hitting ¥2.07 trillion over 15 years — compared with ¥590 billion required to build the Maibara route over 10 years. Given the financial burden on national and local governments of the ongoing construction of other sections of planned bullet-train lines, it will not be until at least 2031 — when the Kanazawa-Tsuruga section of the Hokuriku Shinkansen Line is to be completed — that construction of the remaining section to Shin-Osaka can start.

Building the new superexpress service eventually linking Tokyo and Osaka as a potential substitute to the Tokaido Shinkansen Line in case of a major disaster hitting the nation, such as the much-feared big earthquake in the Nankai Trough off the Pacific, will be important. But given the government’s tight finances, the wisdom of such a costly project — whose construction expenses will be shared between the national and local governments — should still be weighed against its benefits, future demand and profitability.

By 2046, when the planned Hokuriku Shinkansen Line section from Tsuruga to Shin-Osaka will go into service at the earliest, the maglev train service under construction by JR Tokai will have been completed — first linking Tokyo and Nagoya by 2027 and on to Osaka in 2037, according to its plan. Whether train schedules on the Tokaido Shinkansen Line would still be too tight at that time to accommodate Hokuriku Shinkansen Line trains connecting at Maibara needs to be examined.

The Obama route will require construction of many tunnels since it will run through mountainous areas, including the Kyoto Tanba highland quasi-national park with its virgin forests of Japanese cedars and beeches, and habitats of golden eagles, an endangered species, as well as through urban sections of Kyoto. Its environmental impact assessment alone will take five or six years. When the route’s potential problems are identified in the process, the ruling parties and the government should stop and think whether the latest decision is still the most reasonable.

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