Nonlinear effects of built environment on metro-feeder bike-sharing as a dynamic green exposure pathway: a dual perspective of connection frequency and modal share
4 affiliations
- 1School of Civil Engineering and Architecture, University of Jinan
- 2School of Architecture and Urban-Rural Planning, Fuzhou University
- 3Department of Urban and Rural Planning, Southwest Jiaotong University
- 4School of Architecture, Nanyang Institute of Technology
Abstract
Background: Bike-sharing integrated with metro transit can be conceptualized as a potential dynamic green exposure pathway linking blue-green infrastructure, active mobility, and public health. The built environment is a key determinant, but existing research focuses on connection frequency and neglects modal share, which better reflects feeder efficiency and competitiveness.
Objective: This study compares built environment effects on metro-feeder bike-sharing connection frequency and modal share and identifies nonlinear thresholds.
Methods: Using Tianjin, China as a case study, we integrated multi-source travel data with geospatial data. The Green View Index (GVI), derived from Baidu Street View via deep learning, served as a station-catchment-level proxy for potential street-level green exposure. Actual cycling trajectories and health outcomes were not measured. A LightGBM-SHAP model quantified variable contributions and uncovered nonlinear associations.
Results: Three findings emerge. First, connection frequency concentrates in the city center, whereas modal share clusters in suburban ring zones, suggesting spatial unevenness in access to bike-sharing as a green feeder mode. Second, drivers differ: connection frequency is mainly explained by governmental (39.8%), commercial (11.5%), and cultural-educational POI density (9.4%), reflecting commuting-oriented mechanisms; modal share is dominated by healthcare POI density (27.0%), distance to city center (15.0%), and bus stop density (10.0%), highlighting accessibility and inter-modal competition. Third, nonlinear thresholds are pervasive: governmental POI density turns positive beyond 30 POIs/km ² ; GVI above 90 is associated with positive feeder cycling; bus stop density beyond 4 stops/km ² shifts from complementarity to competition; and floor area ratio has an inverted U-shaped effect on modal share, positive at 0.5–2.1.
Conclusion: This study is the first to quantitatively disentangle the differentiated nonlinear effects of the built environment on bike-sharing connection frequency and modal share from both “volume enhancement” and “efficiency optimization” perspectives. The identified thresholds provide evidence-based planning guidance for optimizing metro-feeder bike-sharing systems and supporting climate-adaptive and more spatially equitable green feeder access. Because GVI is a station-catchment proxy and health outcomes were not measured, the health-equity implications are interpretive rather than causal.
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BibTeX
@article{pang2026nonlinear,
title = {{Nonlinear effects of built environment on metro-feeder bike-sharing as a dynamic green exposure pathway: a dual perspective of connection frequency and modal share}},
author = {Lei Pang and Cailin Qiu and Haijun Sun and Xi Ren and Zhong Sun},
journal = {Frontiers in Public Health},
year = {2026},
month = oct,
doi = {10.3389/fpubh.2026.1951162},
url = {https://www.frontiersin.org/articles/10.3389/fpubh.2026.1951162/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Nonlinear effects of built environment on metro-feeder bike-sharing as a dynamic green exposure pathway: a dual perspective of connection frequency and modal share
AU - Lei Pang
AU - Cailin Qiu
AU - Haijun Sun
AU - Xi Ren
AU - Zhong Sun
PY - 2026
DA - 2026/10/27
JO - Frontiers in Public Health
DO - 10.3389/fpubh.2026.1951162
UR - https://www.frontiersin.org/articles/10.3389/fpubh.2026.1951162/full
AB - Background: Bike-sharing integrated with metro transit can be conceptualized as a potential dynamic green exposure pathway linking blue-green infrastructure, active mobility, and public health. The built environment is a key determinant, but existing research focuses on connection frequency and neglects modal share, which better reflects feeder efficiency and competitiveness. Objective: This study compares built environment effects on metro-feeder bike-sharing connection frequency and modal share and identifies nonlinear thresholds. Methods: Using Tianjin, China as a case study, we integrated multi-source travel data with geospatial data. The Green View Index (GVI), derived from Baidu Street View via deep learning, served as a station-catchment-level proxy for potential street-level green exposure. Actual cycling trajectories and health outcomes were not measured. A LightGBM-SHAP model quantified variable contributions and uncovered nonlinear associations. Results: Three findings emerge. First, connection frequency concentrates in the city center, whereas modal share clusters in suburban ring zones, suggesting spatial unevenness in access to bike-sharing as a green feeder mode. Second, drivers differ: connection frequency is mainly explained by governmental (39.8%), commercial (11.5%), and cultural-educational POI density (9.4%), reflecting commuting-oriented mechanisms; modal share is dominated by healthcare POI density (27.0%), distance to city center (15.0%), and bus stop density (10.0%), highlighting accessibility and inter-modal competition. Third, nonlinear thresholds are pervasive: governmental POI density turns positive beyond 30 POIs/km ² ; GVI above 90 is associated with positive feeder cycling; bus stop density beyond 4 stops/km ² shifts from complementarity to competition; and floor area ratio has an inverted U-shaped effect on modal share, positive at 0.5–2.1. Conclusion: This study is the first to quantitatively disentangle the differentiated nonlinear effects of the built environment on bike-sharing connection frequency and modal share from both “volume enhancement” and “efficiency optimization” perspectives. The identified thresholds provide evidence-based planning guidance for optimizing metro-feeder bike-sharing systems and supporting climate-adaptive and more spatially equitable green feeder access. Because GVI is a station-catchment proxy and health outcomes were not measured, the health-equity implications are interpretive rather than causal.
SN - 2296-2565
ER -