Investigation of the Microenvironment, Land Cover Characteristics, and Social Vulnerability of Heat-Vulnerable Bus Stops in Knoxville, Tennessee
Round 1
Reviewer 1 Report
Dear authors!
The relevance of the study is beyond doubt, since the effects of climate change and extreme heat are significant risk factors for public transport passengers. However, there are enough methods and algorithms for the formation of a sustainable urban transport system that require comparative analysis and systematization for conditions of extreme heat and climate change. The references and theoretical background provided are not enough for a scientific paper.
The article describes the problem in sufficient detail, while not fully suggesting ways to solve it. I recommend to systematize the existing methods. Scientific novelty needs improvement. I recommend paying more attention to what is fundamentally new, to reveal the differences between the proposed approach and other studies.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Although the described problem itself (the thesis on the impact of socio-economic conditions on the standard of bus stops) is not original, I appreciate the presentation of the UHI risk analysis methodology. The presented method of analysis does not raise objections and in my opinion does not require additional explanations. It is a pity that the analysis of the results is a description of a case study, without an attempt to present a more generalized model.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Summary
This manuscript covers a pressing topic that squarely aligns with the aims and scope of the journal Sustainability: vulnerability to extreme heat at bus stops through a social equity lens. The study setting is Knoxville, TN, a U.S. city located in a humid subtropical climate and home to residents who mostly identify as white. The authors examined temperature and heat index at bus stops using data from an urban heat island mapping campaign, one of dozens conducted by CAPA Strategies in U.S. cities over the past few years. The authors also leveraged publicly available data from federal sources (USGS, USDA) and private sources (Google) to identify land cover and presence of trees and shelters at bus stops. Lastly, the authors looked at the social vulnerability index and sociodemographic characteristics of census tracts where bus stops were located. The analysis in this paper was either the authors looking at each of these variables singularly, or looking at a variable (i.e., land cover characteristics, presence of tree and/or shelter, social vulnerability index) for a subset of bus stops with high temperatures. The authors showed that bus stops with high temperatures often were located in commercial complexes and where systematically marginalized populations reside.
This paper has noteworthy strengths, in particular its focus at the intersection of environment, health, and equity. I commend the authors for highlighting this critical issue that may worsen in time. Yet there are also a few major limitations that prevent publication in its current form. After major revisions, the paper may be suitable for publication in Sustainability. Below, please see major comments and minor comments requiring attention.
Major Comments
1. While I appreciate the topic pursued by the authors, my enthusiasm waned after understanding the research design: the study was purely descriptive, looking at average temperature and heat index at bus stops, landcover classes of bus stops, presence/absence of trees and/or shelters at bus stops, mean values of social vulnerability index per tract, and percentages of sociodemographic characteristics per tract. Further, the description only seldom explored the intersection between these variables, doing so by focusing on a subset of bus stops with high heat exposure. The study would have been vastly improved if it determined the relations between variables. What’s exciting is the authors have the opportunity to do so through regression modeling, and the authors already have the requisite data to construct variables for their models. This won’t be news to the authors, as they have already identified this as a study limitation (Lines 408-413). The authors should think through which questions they would like to answer with these data, identifying which data are the exposure and outcome variables of interest, and which are included as controls. Independent of whether the authors pursue regression modeling, the Methods section should conclude with content on what analysis was undertaken to get results. As currently written, the Methods section just lists the setting and the different data and processing, before abruptly moving to results. What are these results of?
2. For readability, strongly recommend combining the Introduction and Background sections into a single Introduction section. As currently constructed, there is duplication in both sections (e.g., mention of redlining), and the flow of the manuscript would be improved by having a single cohesive narrative. The authors should write this section concisely, only keeping what’s needed. Here are some main items to consider including in the new Introduction section:
o What’s the issue/problem?
o What have researchers examined in relation to this issue (moving from broad to focused towards your research question(s))
o What is/are the research gap(s)?
o What is the purpose of this paper?
o What is/are your research question(s) to fill the gap(s)?
o What is/are your hypothesis/hypotheses?
o What are the potential implications of your findings?
3. In the Results section, the authors spoke about specific census tract IDs, which is too detailed to be of interest to (and potentially to be understood by) readers who live outside of Knoxville. Consider sharing these results differently. Rather, consider focusing the text on highlighting patterns across tracts (e.g., tracts with higher proportions of Black residents had higher temperature than those with more white residents, on average).
4. The authors defined the microenvironment as trees and shelters yet there are many other micro-scale built environment features around public transit stops or stations. Recommend acknowledging in the paper that there are more features that weren’t measured by authors, several of which may influence the relationship with vulnerability to heat at bus stops. The below article assesses 58 micro-scale built environment features within six categories: Land Use Environment, Transportation Environment, Facilities, Aesthetics, Signage, and Social Environment. Consider including some of these features in your study. Alternatively, the authors can list the omission of these variables as a limitation in the Discussion section, mentioning that future work can include other microenvironment features.
Lanza, K., Oluyomi, A., Durand, C., Gabriel, K. P., Knell, G., Hoelscher, D. M., ... & Kohl III, H. W. (2020). Transit environments for physical activity: Relationship between micro-scale built environment features surrounding light rail stations and ridership in Houston, Texas. Journal of transport & health, 19, 100924.
Minor Comments
Line 18: missing the word “where”. Change to “… and where a large number of…”
Lines 33-34: recommend changing to “Due to discriminatory policies such as redlining,…” to capture that this policy caused inequitable heat exposure. As currently worded, it’s not explicit that this policy was unfair but rather just led to a difference (i.e., disparity) in heat exposure.
Lines 35-36: The authors cite a news article by National Geographic rather than a peer-reviewed study as evidence for communities predominantly inhabited by people of color are more likely to be at risk from urban heat due to limited access to green space. Recommend swapping this citation for a peer-reviewed publication that shows low-income Black and Latino neighborhoods have lower levels of tree canopy than more affluent white neighborhoods:
Lanza, K., Stone Jr, B., & Haardörfer, R. (2019). How race, ethnicity, and income moderate the relationship between urban vegetation and physical activity in the United States. Preventive Medicine, 121, 55-61.
Lines 43-44: the authors include land cover characteristics and presence of trees and shelters as microenvironments yet in Line 12 they define microenvironment as simply trees and shelter. Have to be consistent.
Lines 55-56: rephrase “more enormous proportions” and “more deteriorated”
Throughout manuscript: This is an international journal and therefore recommend the units be in metric system (e.g., Celsius, km). Can still include Imperial units in parentheses, if the authors think appropriate.
Figure 1 should be deleted. The figure does not show us much.
Line 120: change “shape file” to one word.
Lines 122-123: Rephrase “collect three periods of data collection”
Lines 135-138 seem out of place in their current position. Recommend either moving to later in this subsection after first describing the variable as rationale for including the variable. Alternatively, this could potentially be shifted to the Introduction section.
Lines 147-149: include spatial resolution of the NAIP data and the year they were taken.
Line 157: delete “SVI was extracted in CSV File format.”
Change Table 1 to an Appendix.
Figures 2-4: change legends and scale bars such that the values are more appropriate (e.g., round the temperature values to one decimal place) and add units.
Throughout manuscript: authors sometimes state “census tracks” rather than the correct “census tracts”.
Recommend revising the language throughout the manuscript, including sentence structure and word choice. In addition, there is a mix of active and passive voice—recommend sticking with one throughout the manuscript.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Accept after minor revision.
I recommend reflecting the research plan in the introduction.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The authors have done a fine job attending to reviewer comments, resulting in a significantly improved manuscript. If the authors can attend to the following 10 comments, then I would recommend this manuscript for publication in Sustainability.
1. Line 17: change “have poor microenvironments” to “are”
2. Lines 54-56: please provide references for “the effects of UHI vary between regions and populations” and “systematically marginalized populations are more likely to rely on public transport”
3. Line 90: heat index is different than apparent temperature, as the latter includes wind speed. Revise.
4. Throughout manuscript: when mentioning “Centers for Disease Control and Prevention”, be sure to add “U.S.” in front.
5. Table 1. Recommend moving the “Variable names” column to the last column on the right.
6. Figures 1 and 2. Improve readability of annotations over map, and add units for temperature in Legend.
7. Figure 3. There is no way that readers can differentiate the different categories of bus stops for heat index/temperature and time of day. This must be changed.
8. Table 2. Remove the Bus stop IDs in the righthand column. This is too specific to be of interest.
9. In response to my Minor Comment #3 in the initial review, the authors stated they swapped a news article as a reference for a suggested peer-reviewed publication, but this publication is not showing up in the reference list. Please add the below peer-reviewed publication to the reference list.
Lanza, K., Stone Jr, B., & Haardörfer, R. (2019). How race, ethnicity, and income moderate the relationship between urban vegetation and physical activity in the United States. Preventive Medicine, 121, 55-61.
10. There are multiple duplicates in the References. For instance, Li et al. (2022) is both Reference #s 5 and 10; Mital (2023) is both Reference #s 7 and 12; and Lanza et al. (2021) is both Reference #s 28 and 40. Please just include in the reference list once, with the in-text citation referring to that single reference.
There are minor inconsistencies throughout the manuscript. Please review closely and correct.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
