Japan is a mountainous country, so the future demand for tunnels to build safe roads while changing terrain as little as possible is immeasurable. Our company deals with every part of this, from main and facilities planning to inspection, survey and maintenance plans.

Main Planning
We can carry out planning steps such as: internal examination, ground analysis, entrance construction planning, brace installation planning, water proofing/drainage/paving planning, plan execution and provisional planning etc., and the New Austrian Tunnel Method (NATM).
Taking into consideration plan points such as particular ground or site conditions, as well as post-offer O&M, we can analyze the necessary form, scope, and time frame as well as construction methods to build a safe, economical tunnel that meets all building standards.

Shiiyamisaki Tunnel

Kanaga Tunnel

Himi 15 Tunnel

Shiiyamisaki Tunnel
Since a tunnel is a closed space, it is necessary to protect visibility/lighting and have sufficient countermeasures to deal with fires and other accidents. We offer a wide range of detailed plans including lighting equipment, ventilation, emergency facilities (notification and warning equipment, fire extinguishing systems, emergency exit facilities, hydrants, radio rebroadcasters, CCTV etc.), and power distribution equipment.


Lighting (Roadway, Walkway) and Signals


Emergency Telephones / Push-button Messaging, Fire Extinguishers


Jet fans


Entrance Warning Display Signs

Inspection / survey
We gather all information necessary for tunnel O&M, including that needed to set corrective measures for tunnel problems and abnormalities found through inspection and examination, as well as information needed to allow safe, smooth traffic use of the tunnel and prevent damage to third parties. We carry out a wide range of inspection and survey activities, including regular inspections of the tunnel and attached facilities, crack checks, leak detection, and checking for voids behind the liner.


Close Viewing by Inspection Truck


Tap Inspection


Side Wall Inspection


Road Surface Inspection

Maintenance Planning
It's important for tunnel O&M to devise the best response to recover and maintain tunnel functionality and durability based on the results of inspections and surveys. We carry out safe, economical maintenance in order to repair and preserve tunnel functionality, with an eye on effective, reliable methods like External Force Countermeasures, Spalling Countermeasures and Leak Countermeasures.


Before Countermeasures (Full Tunnel)


Before Countermeasures (Arch)


Before Countermeasures (Side Wall)


After External Force Countermeasure Work Full View