GTFS-Based Changes and Spatial Inequality in Interregional Public Transport Mobility-Based Accessibility: A Counterfactual Analysis of Rail and Intercity Bus Removal (2019–2024)

Dongik Jang; Dahee Hong

doi:10.7470/jkst.2026.44.3.482

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2026 Vol.44, Issue 3 Preview Page

Article

GTFS-Based Changes and Spatial Inequality in Interregional Public Transport Mobility-Based Accessibility: A Counterfactual Analysis of Rail and Intercity Bus Removal (2019–2024) GTFS 기반 지역 간 대중교통 이동성 기반 접근성의 변화와 공간적 불균등성: 지역 간 수단 가상 제거 분석(2019–2024)

30 June 2026. pp. 482-496

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Abstract

This study examines changes in interregional public transport mobility in South Korea between 2019 and 2024 using nationwide General Transit Feed Specification data. Rather than measuring accessibility to specific facilities or activities, the study adopts a mobility-based accessibility approach, defining mobility-based accessibility as the share of the national population reachable by public transport within a given travel-time threshold. The analysis is conducted at a 500m × 500m grid level using Statistics Korea’s spatial grid system. Travel times are computed with the R5 routing engine via the r5r package, assuming a 9:00 a.m. departure with a 60-minute sampling window, accounting for scheduled services, transfers, and multimodal connections. Travel-time thresholds of 2.5 and 6.5 hours are empirically derived as the population-weighted median travel times of intra- and inter-municipal trips, respectively. To assess the structural role of different transport modes, a set of counterfactual scenarios is designed in which intercity buses and rail services are selectively excluded from the network. Air transport is excluded from the analysis due to its distinct network structure and usage characteristics in interregional travel. Results show that interregional public transport mobility declined overall during the study period, with substantial spatial heterogeneity. In 2024, the national average reachable population ratio under the full-mode scenario reached 83.9% within 10 hours, dropping sharply to 18.4% when both modes were excluded. The exclusion of rail services leads to the largest reduction at the 6.5-hour threshold (mean slope: -0.889 %p/year), highlighting the critical role of rail in maintaining long-distance mobility. Intercity bus services play a complementary role, but travel-time threshold curve analysis reveals their disproportionate importance in depopulation areas: when intercity buses are excluded, the median reachable population ratio in depopulation areas drops sharply to 16.8% at the 6.5-hour threshold, compared to 83.1% in non-depopulation areas. At the 6.5-hour threshold, the risk of extreme accessibility decline is disproportionately concentrated in depopulation areas (Extreme OR: 22.79), while an OR below 1 at the 2.5-hour threshold reflects a floor effect. These findings demonstrate that mobility losses tend to be concentrated in structurally vulnerable areas, with implications for regional equity and transport policy.

Keywords

counterfactual analysis

depopulation areas

GTFS

interregional mobility

mobility-based accessibility

본 연구는 2019–2024년 전국 General Transit Feed Specification(GTFS) 자료를 활용하여 지역간 대중교통 이동성의 변화를 분석하였다. 이동성 기반 접근성(mobility-based accessibility)은 대중교통으로 일정 시간 이내 도달 가능한 인구 규모를 전국 총 인구 대비 비율로 정의하였으며, 국가데이터처 500m×500m 공간격자 단위에서 R5 라우팅 엔진을 활용하여 산정하였다. 출발시각은 오전 9시 기점 60분 타임 윈도우 내 중앙값을 적용하였고, 시간 임계치는 시군구 단위 지역내·지역간 통행시간의 인구 가중 중앙값을 기준으로 2.5시간과 6.5시간으로 설정하였다. 수단별 구조적 역할을 평가하기 위해 고속·시외버스와 철도를 단계적으로 제외하는 가상 제거 실험을 설계하였다. 분석 결과, 해당 기간 동안 지역간 대중교통 이동성은 전반적으로 감소하였으며 그 영향은 공간적으로 불균등하게 나타났다. 철도 제외 시 도달 가능 인구 비율의 감소가 가장 크게 나타났는데(평균 기울기 –0.889%p/년), 이는 고속·시외버스가 지역간 이동을 전적으로 담당해야 하는 가상 상황에서 팬데믹 이후 고속·시외버스 공급 축소가 이동성 악화로 직결되었음을 보여준다. 고속·시외버스는 전반적인 기여도는 제한적이나, 철도역 접근이 어려운 인구감소지역에서는 사실상 핵심 연결 수단으로 기능하는 것으로 나타났다. 고속·시외버스 제외 시 6.5시간 기준 인구감소지역의 도달 가능 인구 비율 중앙값이 16.8%로 급감하여 비인구감소지역(83.1%)과의 격차가 두드러졌다. 본 연구는 GTFS 기반 이동성 지표와 가상 제거 실험을 결합하여 지역간 대중교통 이동성의 구조적 특성과 공간적 불균등성을 실증적으로 분석하였다는 점에서 의의를 가지며, 향후 지역 균형 및 대중교통 정책 수립을 위한 기초자료를 제공한다.

키워드

가상 제거 분석

인구감소지역

GTFS

지역간 이동성

이동성 기반 접근성

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Information

Publisher :Korean Society of Transportation
Publisher(Ko) :대한교통학회
Journal Title :Journal of Korean Society of Transportation
Journal Title(Ko) :대한교통학회지
Volume : 44
No :3
Pages :482-496
Received Date : 2026-02-11
Revised Date : 2026-02-24
Accepted Date : 2026-05-19
DOI :https://doi.org/10.7470/jkst.2026.44.3.482

Journal of Korean Society of Transportation ISSN:1229-1366(Print) 2234-4217(Online) 대한교통학회지

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