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Tunnel Lighting

Tohoku Chuo Expressway National Route 13 Obanazawa-Shinjo Road Funagata TunnelObanazawa City, Yamagata Prefecture

A conversion to LED for tunnel lighting creates a safe and comfortable lighting environment while realizing significant power savings

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  • LED
  • The tunnel interior is illuminated with LED tunnel lighting fixtures, which have a design operating life of 90000 hours and are equipped with an initial luminous flux correction function, creating a wonderful and highly uniform lighting environment.


Installation date

March, 2020

Funagata Tunnel is a 1368m-long tunnel on the Obanazawa-Shinjo Road, which is an 18.2km motorway in Yamagata Prefecture that runs from Obanazawa, in Obanazawa City, to Matsumoto, in Shinjo City. With a daily traffic volume of more than 10000 vehicles, it functions as a tunnel that is indispensable for traffic access within the prefecture.

In March 2020, the Yamagata Rivers & National Highways Office, which is part of the Ministry of Land, Infrastructure, Transport and Tourism's Tohoku Regional Development Bureau, carried out tunnel lighting installation work to convert the existing HID lighting to LED lighting. For the conversion to LED, the original order involved a design with stainless steel press-fit LED fixtures providing light for the tunnel, which required a high average road surface brightness for its planned daily traffic volume of 13496 vehicles and design-speed of 70 km/h. However, due to revisions to equipment specifications, a proposal was made to reduce the number fixtures by using LED fixtures with aluminum-frames. As a result, the original order of 271 stainless steel press-fit LED fixtures was able to be reduced under the proposal to 192 LEDioc TUNNEL KAE Series aluminum-frame LED fixtures from Iwasaki Electric. By significantly improving the light distribution performance and electrical properties, a reduction in electrical capacity of approximately 45% or more has been achieved compared to stainless steel press-fit LED fixtures. In addition, with the reduction in electric capacitance, we were able to significantly reduce the amount of electricity used compared to the previous HID lighting, achieving power savings of approximately 60% or more (according to an Iwasaki economy comparison table).

By making the change to LED, the visual environment has been greatly improved, increasing the safety of driving in the tunnel.


  • Control section EYE TUNNEL Automatic Dimming Device - 1

  • LEDioc TUNNEL KAE Series

    Base Lighting - 78

    Base Lighting (Emergency Parking Zone Lighting) - 6

    Entrance Lighting - 108

  • LEDioc ROAD - 4

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