The role of a local government planner in unprecedented coordination work

on the undergrounding of the motorway in the middle of Yokohama City

 

Toshio Taguchi

 

Akira Tamura, who subsequently became a renowned Japanese town planner, was assigned by Yokohama’s socialist mayor Asukata a difficult task to solve a tangled argument regarding the design type of the new motorway structure. Tamura joined the city administration in 1968 on Asukata’s request, coming from the private practice as a town planning consultant who had proposed the spine projects to remodel Yokohama in 1964. Its solution became the first example of actual urban design implementation that changed part of the new elevated motorway project undergrounded in the city center. It had been conducted by a local initiative directed by Tamura that had never existed before under its highly centralized administrative system of Japan. The project was conducted through tenacious re-negotiation efforts among concerned parties including the national ministries. These negotiations focused on the critical stage where the central government had made the formal and legal decision on this project.

 

The Metropolitan Motorway Authority (“MMA”) was an institution planning and implementing construction of the motorway network under the auspices of the Ministry of Construction (“MoC”). It was originally established in 1959 to resolve traffic problems of the Tokyo metropolitan area through investments from the national government and the metropolitan government. The MoC ordered the MMA to extend its metropolitan network to the harbor city of Yokohama in 1964. Although Tamura claimed that he was a visionary on townscapes, even from its early period of motorway construction, there was a concern over the preservation of important townscapes among road experts of both institutions. Therefore, some experts saw the use of dried canals as one of the ideal types of motorway structures.

 

In 1964, Tamura also proposed a motorway network by constructing elevated structures over existing rivers or canals in the middle of the city. Despite the city’s motorway section’s idea to utilize unused canals as motorway routes, the underground route encountered severe difficulty in passing closely under the fragile piers of the national railway in the canal. Because of this technical difficulty, Asukata had to abandon hope of undergrounding. However, Asukata later changed his policy back to undergrounding. Since the huge interchange appeared in the middle of the city connecting its motorway with the national network in the suburbs, Asukata recognized that it would devastate the townscape of the city center. During negotiations, relocating the interchange was the most delicate issue to decide. Using the dried canal was fundamentally against the concept of the linear park proposed as an area redevelopment hub envisaged by Tamura. Along the same route in this canal as the motorway, the new subway project planned by the city transport authority in coordination with the Ministry of Transport was already set forward. Eventually, the interchange location was moved to the canal in the periphery of the city center. Reaching an agreement accommodating all requirements of the concerned parties took time, though each party made concessions. 

 

Although Tamura only succeeded in accomplishing part of the extension as being undergrounded, this was thirty percent of the initial motorway extension, which represents the most important section. Tamura needed almost one year to accomplish the negotiation, and then the motorway was finally opened in 1978. Since this successful coordination, Tamura consolidated his position as a new chief planner in the administration. It has become normal among local government officials to be confident and independent as equal partners with the National Ministries. Last, despite Tamura having written about the motorway solution in his books, empirical research on its coordination and background would strengthen Tamura’s achievement.

横浜都心部の関内・関外地区に至る羽田空港方面からの首都高速道路の延伸は、1968年当初、景観とまちづくりの視点から高架か地下かという高速道路の構造と位置をめぐり、横浜市と国や関係機関を巻き込み、おおきな議論を巻き起こした。横浜市が主導した一年間に亘る調整作業により、それまでの構造と位置に関する方針が変更され、全体路線の中心区間の3割が地下構造(トンネル・掘割方式)で建設され1978年に開通した。当該事案は、都市プランナー田村明が横浜市に入って飛鳥田一雄市長から任された最初の仕事であった。その成否によっては、田村が主導する企画調整局の役割も不確かなものになったと想像される。事案そのものは、田村の著書である程度明らかになっているが、主観的な記述であり、これまで歴史的資料に基づいた実証的研究がなされてこなかった。当研究で、それぞれの関係者が何を問題とし、それをどう解決したかの詳細な過程を明らかにした。

田口俊夫『横浜市都心部における高速道路地下化事例にみる自治体プランナーの役割』
都市プランナー田村明が1968年4月に横浜市企画調整室担当部長に就任した。田村が飛鳥田一雄市長の指示で最初に手掛けた仕事が、東京方面から横浜都心部に延伸される首都高速道路の地下化とルート変更であった。一年間に亘る極めて困難な調整作業であった。
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