Evaluating spatial accessibility to healthcare services under travel time uncertainty: A reliability-based floating catchment area approach

AbstractThe regional seismic travel time (RSTT) model and software were developed to improve travel-time prediction accuracy by accounting for three-dimensional crust and upper mantle structure. Travel-time uncertainty estimates are used in the process of associating seismic phases to events and to accurately calculate location uncertainty bounds (i.e. event location error ellipses). We improve on the current distance-dependent uncertainty parameterization for RSTT using a random effects model to estimate slowness (inverse velocity) uncertainty as a mean squared error for each model parameter. The random effects model separates the error between observed slowness and model predicted slowness into bias and random components. The path-specific travel-time uncertainty is calculated by integrating these mean squared errors along a seismic-phase ray path. We demonstrate that event location error ellipses computed for a 90% coverage ellipse metric (used by the Comprehensive Nuclear-Test-Ban Treaty Organization International Data Centre (IDC)), and using the path-specific travel-time uncertainty approach, are more representative (median 82.5% ellipse percentage) of true location error than error ellipses computed using distance-dependent travel-time uncertainties (median 70.1%). We also demonstrate measurable improvement in location uncertainties using the RSTT method compared to the current station correction approach used at the IDC (median 74.3% coverage ellipse).

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Robustifying humanitarian relief systems against travel time uncertainty

Naval Research Logistics (NRL) ◽

10.1002/nav.21981 ◽

2021 ◽

Author(s):

Jianghua Zhang ◽

Yang Liu ◽

Guodong Yu ◽

Zuo‐Jun (Max) Shen

Keyword(s):

Travel Time ◽

Humanitarian Relief ◽

Time Uncertainty ◽

Travel Time Uncertainty

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Correction to: Updates to the Regional Seismic Travel Time (RSTT) Model: 2. Path-dependent Travel-time Uncertainty

Pure and Applied Geophysics ◽

10.1007/s00024-021-02696-0 ◽

2021 ◽

Author(s):

Michael L. Begnaud ◽

Dale N. Anderson ◽

Stephen C. Myers ◽

Brian Young ◽

James R. Hipp ◽

...

Keyword(s):

Travel Time ◽

Time Uncertainty ◽

Travel Time Uncertainty ◽

Path Dependent

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MEASURING SPATIAL HEALTHCARE FACILITIES ACCESSIBILITY USING TWO-STEP FLOATING CATCHMENT ANALYSIS (2SFCA) (Case Study: Cianjur Regency, Indonesia)

Seminar Nasional Geomatika ◽

10.24895/sng.2020.0-0.1115 ◽

2021 ◽

pp. 11

Author(s):

Muhamad Iqbal Januadi Putra ◽

Nabila Dety Novia Utami

Keyword(s):

Travel Time ◽

Quality Of Healthcare ◽

Healthcare Services ◽

Spatial Accessibility ◽

Healthcare Facilities ◽

Spatial Disparities ◽

Time Threshold

The presence of healthcare facilities is quite essential to provide good healthcare services in a particular area, however, the existence of healthcare facilities is not evenly distributed in Cianjur Regency. This condition leads to the disparities of healthcare facilities across the Cianjur Regency. In this paper, we aim to measure and map the spatial disparities of healthcare facilities using a Two-Step Floating Catchment Analysis (2SFCA). This method can calculate the magnitude of spatial accessibility for healthcare facilities by formulating the travel time threshold and the quality of healthcare facilities across the study area. This research shows the result that the spatial accessibility of healthcare facilities in the Cianjur Regency is not evenly distributed across the districts. The spatial accessibility value resulted from 2SFCA is ranging from 0- 3.97. A low value indicates low spatial accessibility, while a higher value shows good accessibility. The majority of districts in the Cianjur Regency have the spatial accessibility value 0-0.5 (86%). Meanwhile, only a few have the higher value; value 0.5-0.99 as much as 6.6%, 0.99-1.49 as 3.3%, and 3.48-3.97 has a percentage of 3.3%. Also, this analysis results in the cluster of good spatial accessibility in healthcare facilities, namely the Pagelaran District and Cipanas District. Interestingly, the downtown of Cianjur Regency has lower spatial accessibility compared to both areas.

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A Robust Optimization Approach for the Express Delivery Routing Problem with Demand and Travel Time Uncertainty

10.1061/9780784483565.227 ◽

2021 ◽

Author(s):

Zhenyu Gu ◽

Cong Chen ◽

Yaoyao Zhu ◽

Jiajia Zheng

Keyword(s):

Robust Optimization ◽

Travel Time ◽

Optimization Approach ◽

Routing Problem ◽

Time Uncertainty ◽

Travel Time Uncertainty ◽

Express Delivery

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Multi-Mode Two-Step Floating Catchment Area (2SFCA) Method to Measure the Potential Spatial Accessibility of Healthcare Services

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi8050236 ◽

2019 ◽

Vol 8 (5) ◽

pp. 236 ◽

Cited By ~ 2

Author(s):

Jianhua Ni ◽

Ming Liang ◽

Yan Lin ◽

Yanlan Wu ◽

Chen Wang

Keyword(s):

Travel Behavior ◽

Urban Areas ◽

Catchment Area ◽

Methodological Approach ◽

Open Data ◽

Healthcare Services ◽

Spatial Accessibility ◽

Urban Residents ◽

Transportation Modes ◽

Multi Mode

While great progress in the development of a methodological approach to measure the accessibility of healthcare services has been made, the exclusion of the complex multi-mode travel behavior of urban residents and a rough calculation of travel costs from the origin to the destination limit its potential for making a detailed assessment, especially in urban areas. In this paper, we aim to describe and implement an enhanced method that enables the integration of multiple transportation modes into a two-step floating catchment area (2SFCA) method to estimate accessibility. We used a travel-mode choice survey, based on distance sections, to determine the complex multi-mode travel behavior of urban residents. Taking Nanjing as a study area, we proposed complete door-to-door approaches to determine every aspect of basic transportation modes. Additionally, we processed open data to implement an accurate computing of the origin-destination (OD) time cost. We applied the enhanced method to estimate the accessibility of residents to hospitals and compared it with three single-mode 2SFCA methods. The results showed that the proposed method effectively identified more accessibility details and provided more realistic accessibility values.

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