Introducing the Green Infrastructure for Roadside Air Quality (GI4RAQ) Platform: Estimating Site-Specific Changes in the Dispersion of Vehicular Pollution Close to Source

Round 1

Reviewer 1 Report

Several references to figures are missing in the text:

e.g., lines:

331,

338,

340,

356,

357,

358,

359.

Correct those, please.

Besides, I have no comments on this very interesting article.

Author Response

Dear Reviewer 1,

Thank you very much for reviewing our manuscript; we are most grateful to you for your time and thought.

We are delighted that you find the article interesting, and regard its Introduction, Research Design, Methods, Results and Conclusions as appropriate, clear and comprehensive.  We will be sure to amend the figure references as indicated.

With our thanks again, and kind regards,

Helen

Reviewer 2 Report

• The paper presents the results related to the dispersion and reduction of pollution without a clear link and recommendations related to the structure of green areas.

 

• This paper stated: "to enable urban practitioners to do this quickly and independently of expensive air quality consultants" (lines 172/173), planning is an integrated process with long-term effects, there is no expert in the process of urban planning that should work independently.

 

• When using the GI4RAQ model/platform in the early stages of urban planning, the planning process of grey and green infrastructure should be side-by-side processes, green infrastructure cannot be used as a nature-based solution for grey infrastructure planning failures. The potential of this platform could be found to help urban practitioners in early phase of planning to define better and to optimize road traffic routes, norms of green areas, and barriers.

 

• When GI4RAQ model/platform is applied to the redesign of existing streets beside street profile/cross-section larger number of variables should be included, such as: traffic safety and visibility, ecological conditions for planting, and maintenance (expenses) of green areas.

 

• The calibration and validation process in the modeling process should be clearly defined, especially when the model finds practical application in practice in making decisions concerning human health and the state of the environment. The validation and calibration of this model were left to future users of the platform, so the validity and accuracy of the results and the impact of the simulated barriers on the dispersion of pollution remained unclear and uncertain.

Author Response

Dear Reviewer 2,

Thank you very much for reviewing our manuscript.

We appreciate your time and thought, and address your points individually below.

With kind regards,

Helen

 

The paper presents the results related to the dispersion and reduction of pollution without a clear link and recommendations related to the structure of green areas.

There is a misapprehension here and we are not sure how it has arisen. Our study relates to the impacts of one aspect of green infrastructure – i.e. street-scale planting schemes (see abstract line 17 and throughout) – and it is not intended to relate to the structure of green areas.

Furthermore, the impacts of vegetation on the dispersion of vehicular pollution at the roadside do not permit generalised recommendations: the suitability of roadside planting interventions (‘GI4RAQ’) depends on the interplay of many site-specific factors: i.e., ‘climatic, meteorological, or morphological conditions’ (Badach et al. 2020). This is precisely why our software is needed: to enable practitioners to estimate the impacts of proposed GI4RAQ, subject to their specific site’s wind conditions, urban form, emissions and background air quality, and to iterate as needed.

This paper stated: "to enable urban practitioners to do this quickly and independently of expensive air quality consultants" (lines 172/173), planning is an integrated process with long-term effects, there is no expert in the process of urban planning that should work independently.

Agreed. It is not our intention to suggest that experts work independently, but rather to say that the software enables initial scoping of the air quality implications of green infrastructure within a street, which would normally require expensive air quality consultants. We have amended lines 172-174 to read:

“The challenge is to predict the site-specific impacts of proposed barriers (i.e., the locations and magnitudes of accompanying benefits and disbenefits) and to enable urban practitioners to do so, irrespective of their specialist area of expertise, as part of comprehensive urban planning teams.”

We have likewise amended the sentence beginning on line 967 to read:

“Our prototype GI4RAQ Platform enables urban practitioners to estimate the site-specific impacts of a proposed intervention quickly, and irrespective of their specialism, as part of urban planning teams.”

When using the GI4RAQ model/platform in the early stages of urban planning, the planning process of grey and green infrastructure should be side-by-side processes, green infrastructure cannot be used as a nature-based solution for grey infrastructure planning failures. The potential of this platform could be found to help urban practitioners in early phase of planning to define better and to optimize road traffic routes, norms of green areas, and barriers.

We completely concur. It is precisely because grey and green infrastructure should be considered side-by-side at the design stage that a tool is needed to assess their combined air quality impacts (i.e., GI4RAQ). We have therefore strengthened this point in our manuscript at line 69:

“The software is applicable to the design of streets in new developments, where it can aid the side-by-side planning of grey and green infrastructure, but also to the redesign of existing streets as part of grey infrastructure modification to encourage modal shift and incorporate planting for reduced pedestrian and cyclist exposure.”

Specifically regarding the air quality impacts of traffic routing, a different type of software is needed – that already exists: e.g. Cambridge Environmental Research Consultants’ ADMS-Roads and ADMS-Urban RML. We have instead developed the GI4RAQ Platform to address a previously unmet need – to estimate the air quality impacts of roadside interventions on ‘within-street’ distributions of vehicular pollution – and received CERC’s support to do so.

When GI4RAQ model/platform is applied to the redesign of existing streets beside street profile/cross-section larger number of variables should be included, such as: traffic safety and visibility, ecological conditions for planting, and maintenance (expenses) of green areas.

Agreed. Our intention is not to replace the existing (re-)design planning processes, but rather to add a light-touch tool that captures a component (or ‘variable’, in the reviewer’s words) that is currently often omitted. To make this clearer, we have amended the manuscript at line 75 to read:

“…a rebalancing of spatial allocations in streets between motorised transport and active travel (e.g. Streetspace Plan for London [14]). When used in street redesign, GI4RAQ will be used alongside many other design checks and balances to consider, for example, traffic safety, visibility, biodiversity and maintenance issues.”

The calibration and validation process in the modeling process should be clearly defined, especially when the model finds practical application in practice in making decisions concerning human health and the state of the environment. The validation and calibration of this model were left to future users of the platform, so the validity and accuracy of the results and the impact of the simulated barriers on the dispersion of pollution remained unclear and uncertain.

We must admit to being at a bit of a loss as to how to respond to this comment, since the manuscript from line 537 to line 781 is entirely given over to evaluation of the model. The reviewer may have been misled by our open admission that there is future scope to improve the model’s predictive skill and scope with the aid of new measurements (line 792). On balance, we do not feel that any changes to the manuscript are necessary on this point.

Reviewer 3 Report

Authors summarise the recent shift in understanding regarding the  impacts of vegetation on urban air pollution towards changes in pollutant dispersion  and describe their prototype software, offering rapid estimates thereof.

The code is open-source to engage further researchers in its continued development. The paper has clear conception and fluent language, which is a good paper worth publishing in the Forests.

Author Response

Dear Reviewer 3,

Thank you very much for reviewing our manuscript; we are most grateful to you for your time and thought.

We are delighted that you consider it a good paper, support its publication in the Forests journal, and note its clear conception and fluent language.  We are also glad that you regard the Introduction, Methods, Results and Conclusions as appropriate, clear and comprehensive.

If you have any specific suggestions regarding improvement of the Research Design, we will endeavour to address these. Likewise regarding any edits to the language used, though we are glad you regard this as ‘fluent’. 

With our thanks again, and kind regards,

Helen

Round 2

Reviewer 2 Report

Dear authors, 
Thank you for submitting your changes. Evaluation of the paper is presented in the reviewer's form (scheme). I have no more suggestions. 
Best regards