来島海峡大橋は，想定される大規模地震時に補剛桁の橋軸方向の変位に起因する損傷が生じることが確認された．この損傷に対し，橋軸方向の補剛桁の変位の抑制を行ったうえで，必要な補強を実施することとした．橋軸方向の補剛桁の変位抑制策として，主塔と補剛桁間への粘性型制震ダンパーの設置が一般的であるものの，吊橋の耐荷性能への影響や維持管理性の不安などの課題がある．そこで，主ケーブルと補剛桁の相対変位の抑制を意図したステイ構造に着目し，既存のステイ構造を摩擦型制震ダンパーに置換する対策を採用することとした．本稿は来島海峡大橋の耐震性能照査及び補強設計について報告するものである．

The damage caused by the displacement of the stiffening girders in the longitudinal direction may occur due to a large-scale earthquake by the result of seismic performance verification for Kurushima-Kaikyo Bridges. For this damage, it decided to limit the displacement of the stiffening girders in the longitudinal direction and then carry out the necessary countermeasure. As the countermeasure, the installation of viscous dampers between the main towers and the stiffening girders is generally common. However, this countermeasure has issues about its affect on the load-bearing capacity of the suspension bridge and maintenance for viscous damper. Therefore, we focused on the stay structure, which is designed to limit relative displacement between the main cables and the stiffening girders, and adopted a countermeasure involving the replacement of the existing stay structure with friction dampers. This paper reports on the seismic performance review and reinforcement design of the Kurushima-Kaikyo Bridge.

神戸淡路鳴門自動車道の大鳴門橋に取り付く3+4径間連続鋼床版箱桁橋である門崎高架橋は，大鳴門橋と同等の高い基本風速（50m/s）を設定しているほか，背後に岬が近接していることから，建設当初から種々の耐風性に関する検討がなされ，橋梁付属物が耐風性に影響を与えることが確認されている．

現在，維持管理方法の見直しにより不要となった箱桁下部作業車レールの撤去が検討されている．しかしながら，撤去にあたっては作業車レールの有無が耐風性に与える影響の評価が必要となるため，風洞試験を実施しその影響を確認した．本稿では，風洞試験結果と作業車レールの影響度について報告する．

The Tozaki Viaduct is a 3+4-span continuous steel box girder bridge with an orthotropic steel deck, connecting to the Ohnaruto Bridge on the Kobe-Awaji-Naruto Expressway. It was designed for a basic wind speed of 50 m/s, equivalent to that of the Ohnaruto Bridge, and was constructed along a coastal promontory. Accordingly, various investigations into aerodynamic stability have been conducted since the initial design stage, confirming that bridge appurtenances have a significant impact on aerodynamic stability.

Currently, removal of the maintenance gantry rails installed on the underside of the girder is under consideration, as they are no longer required due to revisions in inspection and maintenance practices. However, prior to removal, it is necessary to assess the influence of the rails on the aerodynamic stability of the bridge. Therefore, wind tunnel tests were conducted to investigate this influence. This paper reports the wind tunnel test results and evaluates the influence of the maintenance gantry rails.

瀬戸大橋は飛来塩分の多い厳しい腐食環境下にあるため，建設時より重防食塗装系が採用されており，供用後も予防保全の観点から体系的な塗替え塗装が行われてきた．2006年度から開始された1巡目の全面塗替え塗装工事は，2024年度に全て完了し，今後は2巡目以降の維持管理段階に移行することとなる．

本稿では，塗装仕様及びその変遷，点検と劣化評価，トラス橋部における施工上の課題と技術的工夫，今後の展望について，1巡目の塗替え塗装工事の総括として報告する．

Due to the harsh corrosive environment of the Seto-Ohashi Bridge, which is exposed to airborne salt particles, heavy-duty coating has been adopted since its construction. After the bridge was opened to traffic, systematic repainting work has been carried out as a preventive maintenance measure. The first full-scale repainting work, which was begun in fiscal year 2006, was completed in fiscal year 2024. From now on, the maintenance will enter the second cycle.

In this paper, the first repainting cycle are summarized, including the coating specifications and their transition, the inspection and the degradation assessment of painting, technical issues and innovations of repainting work in the truss bridge, and the future outlook.

本州と四国を跨ぐ海峡部長大橋（以下「本四連絡橋」という．）の外面塗装には，重防食塗装が採用されており，犠牲防食層及び下塗り層が損耗する前に塗替塗装を行う予防保全を基本としている．予防保全を行うために現在行っている調査・点検手法はいずれも橋梁塗膜に近接する必要があり，また定点での評価となるため多大な労力と時間がかかる．そこで近赤外線分光法に着目し橋梁塗膜の全面を効率的に評価する手法について検討している．本稿では，実橋にて実施した近赤外線ハイパースペクトル計測（以下「近赤外線HS計測」という．）を用いた試験計測とその結果について報告する．

The long-span bridges connecting Honshu and Shikoku have been coated with heavy-duty anticorrosion coatings.Before the sacrificial corrosion layers and under layers are exposed, the repainting have been conducted based on the preventive maintenance policy. However, current inspections and survey methods for preventive maintenance require close visual inspections to the bridge coating and evaluate only at fixed points.As a result, a lot of work and time are needed. Therefore, we are investigating a method for efficiently evaluating the entire bridge coating using near-infrared spectroscopy. This paper reports on several methods and their results using near-infrared hyperspectral measurement (near-infrared HS measurement) on an actual bridge.

吊橋のハンガーロープや斜張橋のケーブル（以下，「ケーブル」という）の張力は，点検管理要領(長大橋梁点検)において，精密点検時に測定することが規定されている．現在，ケーブル張力測定は通常，振動法で行っている．これに使用するポータブルFFTアナライザ（以下，「FFTアナライザ」という）は，高精度ではあるものの，重量があることや別途加速度センサーなどを接続する作業が必要なことから測定作業の効率が悪く，また価格も比較的高価であることが課題であった．これらを解決するため，計測及び解析を1台のスマートフォンで振動計測を行う方法を考案した．現在も実橋の種々のケーブル張力測定作業に使いFFTアナライザによる測定値と比較するとともに解析アプリの改良を行っている．本文では，振動法による張力の測定方法，これまでの取組，現状の課題と対策について報告する．

The tension of hanger ropes in suspension bridges and cables in cable-stayed bridges is required to be measured during a detailed inspection as stipulated in the Inspection and Maintenance Manual for Long-Span Bridges.

A portable FFT analyzer has been used up to now for cable tension measurement provides high accuracy; however, it is heavy, requires to connect sensors, and is more costly, resulting in low operational efficiency. To address these issues, we have devised a method for cable tension measurement by vibration using a smartphone and have been improved it through field measurements on actual bridges. This paper reports on the method for cable tension measurement by vibration , past efforts, current problems, and corresponding countermeasures.

吊橋の主ケーブルには，素線の防食のため乾燥空気を送風する「ケーブル送気乾燥システム」が導入されている．このシステムによる主ケーブル防食の実効性を確保するためには，主ケーブル内部の温湿度監視が重要であり，自動や手動のモニタリングを実施している．自動監視ではシステム構築に労力を要し，手動監視では高所の主ケーブル上での点検員による測定作業が必要となる．

本稿は，近年手軽に扱えるようになった低消費電力で，長距離無線通信のIoT（Internet of Things）技術を活用し，インターネットや社内LANなどを介して遠隔から情報閲覧することを目標に開発した「新たなケーブル送気監視システム」とシステム導入により期待できる効果などを報告する．

To protect the wires of the main cables of suspension bridges from corrosion, a dry-air injection system has been installed, which circulates dry air through the cables. In order to ensure the effectiveness of this system, it is essential to monitor the temperature and humidity inside the main cables. Both automatic and manual monitoring methods are currently being used. Automatic monitoring requires significant effort in system construction, and manual monitoring requires performing measurements by inspectors on the main cables at high elevations.

This paper reports on the development of a new dry-air injection monitoring system, which leverages recent advancements in low-power, long-range wireless IoT (Internet of Things) technology. The goal is to enable remote access to monitor data via the Internet or internal LAN. Additionally, the paper discusses the potential benefits expected from the introduction of this system.

道路橋は，国土交通省の道路橋定期点検要領で定められた近接目視による状態把握（点検）が必要である．海峡を跨ぐ吊橋などの長大橋も同様であるが，これら長大橋は主ケーブルやハンガーロープなど，高所かつ海上部に位置した近接困難な部材が多数存在する．これらの部材のうち吊橋の主ケーブルについて，簡易かつ効率的に点検を行うことができるよう，主ケーブル全周方向画像の撮影及び画像解析による変状把握が可能な主ケーブル外装モニタリングシステムを開発した．本文ではこれまでの取組，現状の課題と対策について述べる．

Road bridges require close visual inspection to assess their condition, as stipulated by the Ministry of Land, Infrastructure, Transport and Tourism's Road Bridge Periodic Inspection Guidelines. The same applies to long-span bridges such as suspension bridges that span straits, but these bridges have many components that are difficult to access, such as the main cables and hanger ropes, which are located high above the water. To enable simple and efficient inspection of the main cables of suspension bridges, we have developed a main cable exterior monitoring system that can capture images of the entire circumference of the main cable and identify any abnormalities through image analysis. This paper describes the efforts made so far, as well as current issues and countermeasures.

ETC2.0は，路側に設置された通信アンテナ（以下，「ITSスポット」という）と車載器が双方向通信を行うことで情報提供・収集を行うことができる（図－1）．収集したデータには車両の走行速度などの情報が含まれ，交通管制業務や交通解析に使用するが，データはITSスポット通過時に収集するため，ITSスポットの配置距離などにより，情報の収集にタイムラグが発生してしまう．

今回，AI補正機能を追加し，受信前のデータをAIが予測することで，リアルタイム交通状況を予測することが可能となった．これは早期の渋滞把握，渋滞情報提供の精度向上に寄与するものである．本稿では，ETC2.0及びAI補正機能の仕組みについて述べるとともに，AI補正機能の精度検証結果について報告する．

ETC 2.0 enables the provision and the collection of information through bidirectional communication between vehicle-mounted devices and roadside communication antennas (hereafter referred to as ITS Spots)(Fig.1). The collected data includes information such as vehicle speed, which is used for traffic control operations and traffic analysis. However, since data is collected only when passing an ITS Spot, a time lag in data acquisition can occur depending on the placement distance of the ITS Spots.

This time, an AI correction function has been added, allowing real-time traffic conditions to be predicted by having AI forecast data before it is received. This contributes to early detection of traffic congestion and improved accuracy in providing congestion information. In this paper, we describe the mechanisms of ETC 2.0 and the AI correction function, and report the results of accuracy verification for the AI correction function.

長大橋梁の保全作業を安全かつ効率的に施工するには，橋梁点検補修用作業車が不可欠である．作業車の安全かつ適切な運用にあたっては，ガイダンス式操作盤などによる誤操作防止機構の導入や，学科と実技による安全運転教育の実施により，安全性の確保と向上を図ってきた．しかし，作業車の進行方向障害物の確認不足などによるヒューマンエラーに起因する接触事故を防止することは困難であった．このため，瀬戸大橋ではヒューマンエラーによる接触事故防止を目的に，最新のセンシング技術を活用した新たな安全装置の導入を検討し，更なる安全性能の高度化に取り組んだ．

本稿では，作業車の安全性能高度化に向けたセンサ方式の選定，検出性能の確認及び実橋試験による実用性の確認などの取組について報告する．

To ensure the safe and efficient execution of maintenance operations on long-span bridges, the maintenance vehicle is indispensable. In order to achieve the safe and proper operations of the maintenance vehicle, various measures have been implemented, including the introduction of error-prevention mechanisms such as guided control panels, as well as safety training programs incorporating both theoretical and practical components.

However, it has been difficult to prevent contact accidents caused by human error, such as insufficient confirmation of obstacles in the travel direction of the vehicle. To prevent these accidents, efforts have been undertaken on the Seto-Ohashi Bridges to further enhance safety performance by evaluating the effectiveness of newly introduced safety devices that utilize state-of-the-art sensing technologies, with the goal of preventing contact accidents attributable to human error.

This paper presents an overview of the initiatives aimed at improving the safety performance of the maintenance vehicle, including the selection of appropriate sensor technologies, verification of detection capabilities, and validation of practicality through on-site testing using an actual bridge.

瀬戸大橋に設置している桁外面作業車は，定期点検時に伸縮足場昇降用ワイヤーロープの表面に減摩及び長寿命化などを目的として潤滑油を人力で塗布している．しかし，潤滑油の塗布作業は側面フレーム内の狭隘かつ高所で実施することから転落及びワイヤーロープ巻取ドラムへの巻き込まれなどが危惧される．これらの問題点を解決するため，既存のワイヤーロープ自動塗布装置を参考に自動で潤滑油の塗布を可能にしたオリジナル塗布機を考案し，安全・衛生の向上及び作業の簡素化と省工程化を図った．

本稿では，ワイヤーロープ潤滑油塗布作業の安全・衛生の向上などに向けた自動塗布装置考案の取組について報告するものである．

The maintenance vehicle for outside girder installed on the Seto Ohashi Bridge applies lubricant manually to the surface of the wire rope used for raising and lowering the telescopic scaffolding during regular inspections for the purpose of reducing friction and extending the service life. However, since the lubricant application work is performed in a narrow and high place inside the side frame, there is a risk of falling and getting caught in the wire rope winding drum. To solve these issues, we devised an original application device that enables automatic lubricant coating, based on existing automatic application device for wire rope, with the aim of improving safety and hygiene, simplifying work, and streamlining processes. This paper reports on efforts to develop an automatic application device aimed at improving safety and hygiene in the application of lubricants to wire ropes.