特急「かささぎ」減便と本当に守るべき地域の移動手段／Kasasagi Limited Express Service Reductions and the Transport Services That Should Really Be Protected

特急「かささぎ」減便と本当に守るべき地域の移動手段

JR九州が2026年春のダイヤ改正で特急「かささぎ」を1日上下14本から約10本に減便する方向で調整している報道を受け、議論は「特急を守るかどうか」に終始しがちです。しかし地域の実利を守る観点から最も重要なのは、江北（肥前山口）〜諫早間の普通列車の運行本数を抜本的に増やすことです。元々この区間の普通列車は「1日数往復」という、限界ローカル線並みの運行密度に落ち込んでおり、まずここを正すべきです。

背景と現在の問題点

西九州新幹線の開業で並行在来線の利用は新幹線側へ移行し、在来線特急の利用は低迷しています。かささぎは大編成で運行される一方、乗車率は極めて低く、特急の効率性だけを見れば減便は理解できます。しかし、問題の本質は普通列車の本数不足にあります。日常の通勤・通学・買物・通院を支えるのは特急ではなく普通列車であり、1日数往復では地域の生活ニーズは満たされません。

提案の要点

• 最優先は普通列車の倍増以上。江北〜諫早間の普通列車を段階的に「倍増以上」に引き上げることを中心に据える。
• 目的は日常利便の確保。通勤・通学時間帯を中心に本数を増やし、「乗れない」「接続が悪い」から生じる移動の制約を解消する。
• 特急減便はその前提で議論。減便による運力削減分を単に失わせるのではなく、地域の移動を支える普通列車増発へ再配分する。

実行プラン（段階的アプローチ）

1. 短期（試験）
• 朝夕中心に臨時で数往復を追加し、1〜3か月で実乗データを収集する。
2. 中期（恒常化）
• 試験結果を基に、1日ベースで「倍増以上」の恒常ダイヤへ移行。編成と乗務員を確保し、コスト試算を行う。
3. 長期（最適化）
• 利用実績に応じ停車パターンや接続を最適化。イベント・観光時の増発ルールも整備する。

調整すべき視点と関係者の役割

• JR九州: 運行計画の策定、車両・人員配分、試験運行の実施とデータ公開。
• 自治体（佐賀県・沿線市町）: 試験支援や初期補助、利用促進策の実施。
• 住民・事業者: 具体的な利用時間帯やニーズを提示し、試験の精度を高める。
• 評価指標: 乗車人員、継続利用率、運行コスト対効果、住民満足度。

まとめ

特急「かささぎ」減便の是非だけを争うのではなく、地域の生活を支える普通列車の運行密度こそが議論の中心であるべきです。江北〜諫早間の普通列車を倍増以上に増やすことで、日常移動の利便性を確保し、特急に依存しない持続可能な地域輸送体系を構築できます。まずは短期の試験運行で実データを集め、透明な形で自治体と事業者が合意形成を行うことを強く提案します。

 

Kasasagi Limited Express Service Reductions and the Transport Services That Should Really Be Protected

Following reports that JR Kyushu is planning to reduce the Kasasagi limited express from 14 round trips per day to about 10 in the spring 2026 timetable revision, public debate has focused on whether to preserve the limited express. From the perspective of protecting residents’ everyday mobility, however, the priority should be to drastically increase the number of local (ordinary) trains between Kōhoku (formerly Hizen-Yamaguchi) and Isahaya. That section already operates at a level comparable to a marginal rural line—just a few round trips per day—and this must be corrected first.

Background and Current Issues

The opening of the West Kyushu Shinkansen shifted passengers to the high-speed line and depressed demand for parallel conventional limited expresses. Although Kasasagi runs with large trainsets and very low load factors—so a reduction is understandable from an efficiency standpoint—the core problem is the scarcity of ordinary trains. Daily commuting, school travel, shopping, and medical visits depend on ordinary trains rather than limited expresses. With only a handful of round trips per day, the line cannot meet residents’ everyday mobility needs.

Key Proposals

• Priority is doubling or more of ordinary train frequency. Center policy around a staged increase of ordinary trains between Kōhoku and Isahaya to at least double current levels.
• Objective is securing daily mobility. Increase frequencies especially in commuting and school commute windows to eliminate constraints caused by “no trains available” or poor connections.
• Discuss limited express reductions on that basis. Any reduction in limited-express services should be considered only after reallocating capacity toward boosting ordinary-service frequency so residents do not suffer a net loss of mobility.

Implementation Plan Stages

1. Short term Trial
• Add several temporary round trips focused on morning and evening peaks and collect ridership data over 1–3 months.
2. Medium term Normalization
• Based on trial results, shift to a permanent timetable that raises daily ordinary services by at least twofold; secure rolling stock and drivers and produce realistic cost estimates.
3. Long term Optimization
• Adjust stopping patterns and connections according to usage, and establish procedures for supplementary services during events or tourist seasons.

Stakeholders and Key Considerations

• JR Kyushu: plan operations, allocate rolling stock and crews, run trials, and publish data.
• Local Governments: (Saga Prefecture and affected municipalities) support trials with initial subsidies and demand-promotion measures.
• Residents and Businesses: provide concrete information about peak travel times and needs to improve demand estimates.
• Evaluation Metrics: ridership, retention rate after trials, cost-effectiveness, and resident satisfaction.

Conclusion

The debate over Kasasagi should not be limited to whether the limited express is retained. The central issue is the density of ordinary train services that sustain daily life. Doubling or more the ordinary services between Kōhoku and Isahaya would secure daily mobility, reduce reliance on limited expresses for local needs, and create a more sustainable regional transport system. Begin with a short-term trial to collect transparent data, and pursue joint, evidence-based agreement between local governments and JR Kyushu.