Strategies to Reduce Pollutant Emissions in the Areas Surrounding Airports: Policy and Practice Implications

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The main aim of the article was to propose a strategy for reducing the emission of pollutants in the areas surrounding airports. The intermediate goals were to identify the main factors contributing to the pollution of the areas surrounding the airport and to propose actions to mitigate the analyzed situation. The authors based their research on the analysis of the situation at two Italian airports. The authors determined the emissions of pollutants for the studied airports and proposed actions to mitigate the emissions.

In my opinion, the article is well organized and written.

Minor comments: double numbering of some literature items, e.g. lines: 461, 466, 470, 474 and subsequent ones.

Author Response

Reviewer 1

The main aim of the article was to propose a strategy for reducing the emission of pollutants in the areas surrounding airports. The intermediate goals were to identify the main factors contributing to the pollution of the areas surrounding the airport and to propose actions to mitigate the analyzed situation. The authors based their research on the analysis of the situation at two Italian airports. The authors determined the emissions of pollutants for the studied airports and proposed actions to mitigate the emissions.

In my opinion, the article is well organized and written.

Thank you dear Reviewer for your valuable comments and suggestions that helped us to improve the quality of our paper. All corrections are available in the track-change file

Minor comments: double numbering of some literature items, e.g. lines: 461, 466, 470, 474 and subsequent ones.

Thank you very much for highlighting this mistake. We corrected it

Reviewer 2 Report

Comments and Suggestions for Authors

 

This study investigates the major contributors to airport emissions and uses real cases in Italian. The writing of this manuscript is clear. I have the following comments.

1. The contribution of this method is unclear; what is innovative about this approach?

2. The formulation of the equations needs to be more standardized. Equation (1), The lowercase letter x cannot be used to represent multiplication in academic writing. Please use a proper equation editor. In lines 261-262, the symbols in the equations need to be italicized.

3. What is the limitation of this study?

4. Does this study provide any practical assistance or guidance?

 

 

Author Response

Reviewer 2

This study investigates the major contributors to airport emissions and uses real cases in Italian. The writing of this manuscript is clear.

We thank you dear Reviewer for the quality remarks and suggestions which largely improved the paper. All corrections are available in the track-change file

I have the following comments.

We revised the manuscript taking into account all the reviewer’s concerns. We report below a detailed description of our changes.

The contribution of this method is unclear; what is innovative about this approach?

The innovative aspect of the study consists in the holistic approach of the problem. We added at lines 109 on and 172 on, respectively:

In particular, (as explained in section 4.1), by answering the two research questions, the study aims to fill a gap in land use and mobility policies with regard to emissions in the airport environment, where pollution from air traffic is often neglected in urban master plans or mobility plans, and vice versa, pollution from surface transport is little considered in airport master plans.

 

The impact of the airport on air pollution is addressed by considering different aspects of local mobility: those due to access mobility (road vehicles) to the airport and those due to the mobility of aircraft.

2. The formulation of the equations needs to be more standardized. Equation (1), The lowercase letter x cannot be used to represent multiplication in academic writing. Please use a proper equation editor. In lines 261-262, the symbols in the equations need to be italicized.

We revised the equation with a proper equation editor

3. What is the limitation of this study?

We specified the limitation of this study at lines 181 on by adding:

Likewise, the overall approach can be applied to any airport where access is limited to road mobility (with no rail supply), and results apply to medium-sized air-ports, although the methodology can be up/downscaled to any type of facility.       

4. Does this study provide any practical assistance or guidance?

We discussed about this aspect in paragraph 4.1 and 4.2, but we have better specified this aspect at lines 183 on

The study can be used as a reference for the management of land adjacent to airports, for the planning of both access infrastructures to the airport and those dedicated to the ground mobility of aircraft (taxiways).

Reviewer 3 Report

Comments and Suggestions for Authors

Preamble

This reviewer was a member of a national policy advisory committee on noise and air quality management plans when a government-owned airport was proposing a new runway at an international airport. He/she also conducted an international benchmarking study of major airports in North America, Europe and Asia on issues of noise, pollution and ground access (especially rail).

Aims

The paper aims to determine which is the major contributor of emissions – ground transport access to airports or aircraft emissions when taxiing, take-off and landing? It then asks, what mitigation measures can be applied? This paper addresses these questions through two Italian case studies. 

Methodology

Estimates of emissions from passenger cars, and buses are made from the COPERT model. Aircraft emissions are calculated using ICAO methodologies for each LTO cycle. The results are presented in a series of tables. Two avenues of action are suggested to mitigate emissions: (i) adapting land use and mobility regulations and policies to include air transport when planning and enforcing measures involving multimodality, and (ii) managing airport operations by adopting more sustainable solutions, such as single-engine taxiing, dispatch towing, taxiing with onboard systems, and reducing taxiing time. A discussion of the policy implications completes the methodology.

Evaluation

The introduction reviews literature on aircraft emissions and on emissions from road-based vehicles accessing airports. The argument for the lack of planning studies that cover emissions from both modes, and an explanation of the reasons why this is the general case, is an important one. The case study of two small airports is a limiting factor because both noise and air pollution impacts explode in significance in metropolitan areas where there are inner city airports.

There are a few important omissions in the literature covered in the introduction. First, as the topic is emissions from transport, there should be some recognition of the public health and environmental effects of the pollutants mentioned. Secondly, noise is mentioned for the first time on line 332 and some statement about noise impacts should appear in the literature review, especially from a community perspective. This reviewers’ understanding of the literature is that aircraft noise is a major environmental disturbance when compared with aircraft emissions (unless a resident is very close to the airport boundary, and this is mitigated by land use zoning based on ANEF contours that exclude residential developments). Thirdly, public participation is mentioned on line 319 but there is no reference in the introduction.

On the description of the case study airport, prevailing wind patterns and the relation of urban developement around the airport are important for two reasons. First are air quality measurements recorded around the case study airports? Do the prevailing winds predominantly move airborne pollutants away from residential areas? Do meteorological conditions, such as temperature inversions, have any local effects on ground level pollution?

Secondly, the compass direction of the wind will have an airport operational directive on runways usage (presumably the small case study airport has a cross-wind runway).

In summary, this paper represents a careful analysis of emissions from the road based transport and the aviation sectors, but is limited for an international readership due to the fact that the case study airport is a small one.

Minor comments

Table 1 can be improved by adding ratios.

References are inconsistent with journal titles with both u/c and l/c lead letters.

When searching the literature on community consultation the following reference might be useful.Black J.A., “Policy Processes and Noise and Air Quality Management Plans at Sydney Airport: The Value of Research into Organisational Communication Strategies”, 21^st ATRF, Adelaide, September 1997, Papers of the Australasian Transport Research Forum, Vol 21, Part 2, pp. 663-676, ISBN 0 86803 2476.

 

Author Response

Reviewer 3

Preamble

This reviewer was a member of a national policy advisory committee on noise and air quality management plans when a government-owned airport was proposing a new runway at an international airport. He/she also conducted an international benchmarking study of major airports in North America, Europe and Asia on issues of noise, pollution and ground access (especially rail).

We thank the Reviewer for all the valuable comments and suggestions provided, all much appreciated and helpful to improve the quality of our paper. All corrections are available in the track-change file

Aims

The paper aims to determine which is the major contributor of emissions – ground transport access to airports or aircraft emissions when taxiing, take-off and landing? It then asks, what mitigation measures can be applied? This paper addresses these questions through two Italian case studies. 

Methodology

Estimates of emissions from passenger cars, and buses are made from the COPERT model. Aircraft emissions are calculated using ICAO methodologies for each LTO cycle. The results are presented in a series of tables. Two avenues of action are suggested to mitigate emissions: (i) adapting land use and mobility regulations and policies to include air transport when planning and enforcing measures involving multimodality, and (ii) managing airport operations by adopting more sustainable solutions, such as single-engine taxiing, dispatch towing, taxiing with onboard systems, and reducing taxiing time. A discussion of the policy implications completes the methodology.

Evaluation

The introduction reviews literature on aircraft emissions and on emissions from road-based vehicles accessing airports. The argument for the lack of planning studies that cover emissions from both modes, and an explanation of the reasons why this is the general case, is an important one. The case study of two small airports is a limiting factor because both noise and air pollution impacts explode in significance in metropolitan areas where there are inner city airports.

We are sorry for this misunderstanding, but nowhere in the text is reported that these are two small-size airports. Actually, the dimensions of the two airports are very common in Europe where they are considered medium-size. Moreover, the two airports are very close two metropolitan Italian areas where the road traffic flow is very high and case study 1 is an inner city airport. We clarified that results apply to medium-size facilities at line 181

There are a few important omissions in the literature covered in the introduction. First, as the topic is emissions from transport, there should be some recognition of the public health and environmental effects of the pollutants mentioned. Secondly, noise is mentioned for the first time on line 332 and some statement about noise impacts should appear in the literature review, especially from a community perspective.

We agree with the reviewer: there is a vast literature on the noise, but this article focus only on air pollution. However, noise and public health references have been added in the literature review to improve its quality. Likewise, for the community perspective topic. Thank you for suggesting this. Text amended from line 74 to 84 and several new references added.

This reviewers’ understanding of the literature is that aircraft noise is a major environmental disturbance when compared with aircraft emissions (unless a resident is very close to the airport boundary, and this is mitigated by land use zoning based on ANEF contours that exclude residential developments). Thirdly, public participation is mentioned on line 319 but there is no reference in the introduction.

Again, we agree with the reviewer. Thank you for suggesting this. Text amended from line 86 to 89 and new references added.

On the description of the case study airport, prevailing wind patterns and the relation of urban developement around the airport are important for two reasons. First are air quality measurements recorded around the case study airports? Do the prevailing winds predominantly move airborne pollutants away from residential areas? Do meteorological conditions, such as temperature inversions, have any local effects on ground level pollution?

Although aware of the importance of the diffusion of pollutants in the environment, the study was carried out only on the emission of pollutants and their diffusion was not considered because out of scope. To be noted that urban air quality measurements take place at monitoring stations close to the case study airports, but are not airport-site specific.

Explanatory sentences added at line 171 on and 223 on, respectively:

….with comparable weather effects in terms of temperature inversion and low speed winds phenomena.

To be noted, that although emission diffusion was not investigated, local low wind speeds and occasional temperature inversion phenomena allow pollutants to accumulate near the ground, thus exacerbating the magnitude of the pollution levels.

Secondly, the compass direction of the wind will have an airport operational directive on runways usage (presumably the small case study airport has a cross-wind runway).

The airports studied in this paper has only one runway. We added this information at lines 99 and 101

In summary, this paper represents a careful analysis of emissions from the road based transport and the aviation sectors, but is limited for an international readership due to the fact that the case study airport is a small one.

As said, the dimensions of the two studied airports are very common in Europe where they are and considered as medium-sized airports. We specified the limitation of this study at lines 180-181 by adding:

Likewise, the overall approach can be applied to any airport where access is limited to road mobility (with no rail supply), and results apply to medium-sized air-ports, although the methodology can be up/downscaled to any type of facility

Minor comments

Table 1 can be improved by adding ratios.

We added a comment just after table 1 at lines 221 on, to highlight the increment of emissions between the two traffic types

 

References are inconsistent with journal titles with both u/c and l/c lead letters.

We corrected the format

 

When searching the literature on community consultation the following reference might be useful. Black J.A., “Policy Processes and Noise and Air Quality Management Plans at Sydney Airport: The Value of Research into Organisational Communication Strategies”, 21^st ATRF, Adelaide, September 1997, Papers of the Australasian Transport Research Forum, Vol 21, Part 2, pp. 663-676, ISBN 0 86803 2476.

We added this reference, thank you for suggesting it