Cross-Regional Highway Built through a City Centre as an Example of the Sustainable Development of Urban Transport

Round 1

Reviewer 1 Report

Here are my comments
- section 2.2 is missing (please check section numbering)
- the authors compare observations before and after DTS. But there are also other approaches to evaluate the impact of construction of roads, notably air quality models. Please in the introduction consider mentioning i.e. these works: https://doi.org/10.1016/j.envsoft.2012.09.003, https://doi.org/10.1016/j.envsoft.2020.104904, etc...
- the periods considered are: before DTS (Apr-May 2012), after DTS (May-Jul 2016). As the periods are different, also meteorology could play a role in the different observed values. The authors should mention and analyize this aspect.
- the authors should comment more on the change of kilometers driven due to DTS construction. The change on kilometers driven (from 2012 o 2016) will also impact air quality.

Author Response

November 15, 2020

Manuscript ID: sustainability-999898

Title: "Cross-Regional Highway built through a city centre as an example of the sustainable development of urban transport"

 Response to the comments of Reviewer 1

 We appreciate your response and the helpful suggestions for improving the presentation of our study. We have detailed our modifications as they relate to your comments on the original manuscript.

 - section 2.2 is missing (please check section numbering)

It has been corrected.

- the authors compare observations before and after DTS. But there are also other approaches to evaluate the impact of construction of roads, notably air quality models. Please in the introduction consider mentioning i.e. these work:

https://doi.org/10.1016/j.envsoft.2012.09.003, https://doi.org/10.1016/j.envsoft.2020.104904, etc...

We have improved the introduction by putting the following fragment:

One of the possibilities to investigate the effects of opening a new road is to make use of a “natural experiment”, when a change in pollutants concentrations can be monitored (Burr et al. 2004). On the other hand, the change in traffic policy requires high investments. Therefore, research is needed to prove the positive environmental effect of the planned investment. To correctly estimate the planned investment the modelling tools are particularly helpful. Citing (Degraeuwe et al. 2021) many tools are available to model yearly, daily and hourly particulate matter (PM) and NO₂concentrations at street level taking into account urban topography, emission performance of vehicles, the composition of the vehicle fleet, the daily activity patterns, as well as background pollution. Additionally, activity based models can cover a nationwide region, while still providing sufficient detail to assess effects on a local scale and for different population subgroups (Dhondt et al. 2013). As an example, the results from the SHERPA-city application can be recommended (Degrauewe et al. 2019) or an activity-based model which illustrates the impact of different trip motives on PM₁₀ and O₃ concentrations as well as the intra-daily NO₂ cycle (Lefebvre et al. 2013).

 - the periods considered are: before DTS (Apr-May 2012), after DTS (May-Jul 2016). As the periods are different, also meteorology could play a role in the different observed values. The authors should mention and analyze this aspect.

We have added the following fragment at the beginning of the Results section:

It is expected that meteorological parameters are interlinked in various ways with NO₂ levels in ambient air. However, it is difficult to assess the effect of each separate meteorological factor on NO₂ pollution. Studies involving analysis of NO₂ ambient levels as a function of meteorological parameters strongly depend on local factors (Voiculescu et al. 2020; Çelik and Kadi 2007; Dominick et al. 2012). According to (Elminir 2005), the NO₂ concentration is slightly higher at a lower relative humidity, whereas other authors found that the NO₂ concentration correlates positively with the relative humidity in all seasons, especially during winter (Gasmi et al. 2017). A negative correlation between wind speed and NO₂ concentration was found by (Zhou et al. 2014; Habeebullah et al. 2015; Hosseinibalam and Hejazi 2012). However, their analysis constructed by averaging pollutant concentration by wind speed use categories: 0–1 m/s, 1–2 m/s, etc. or ranges < 2m/s and >2m/s. As it can be seen the difference in humidity and wind speed is not significant. On the other hand, the difference in temperature between both sessions was 10.5°C. However, the relation between NO₂ and temperature is inconsistent. The correlation was found to be insignificant or weak (Day, Wooldridge, and Cohen 2008; Habeebullah et al. 2015), other studies found strong positive correlations between the NO₂concentration and temperature for all seasons (Gasmi et al. 2017). The research (Voiculescu et al. 2020; Kendrick, Koonce, and George 2015; Elminir 2005) underline, that the seasonal variation of NO₂ is only evident when compare summer/spring with fall/winter. Our intention was to avoid the measurements during the most dissimilar seasons.

- the authors should comment more on the change of kilometers driven due to DTS construction. The change on kilometers driven (from 2012 o 2016) will also impact air quality.

We have added the following fragment at the Strengths and limitations section:

In Gliwice the number of kilometers before 2012 that had to be driven within the city borders in the east-west direction was 9.4 km, and after the road was built (2016) it is 8.1 km. Shortening this distance leads to a reduction of NO₂emissions from vehicles and a reduction of the environmental burden of this pollution.

 Again, we would like to express our appreciation for your efforts and helpful comments. Enclosed, please find the revised version of our paper.

 Yours sincerely,

Anna Mainka and Magdalena Żak

 Author Response File: Author Response.pdf

Reviewer 2 Report

See attached. 

Comments for author File: Comments.pdf

Author Response

November 15, 2020

Manuscript ID: sustainability-999898

Title: "Cross-Regional Highway built through a city centre as an example of the sustainable development of urban transport"

 Response to the comments of Reviewer 2

 We appreciate your response and the helpful suggestions for improving the presentation of our study. We have detailed our modifications as they relate to your comments on the original manuscript.

 Main Comments:

The authors conclude that an observed reduction in NOx concentrations is due to construction of a bypass highway through a city center. While plausible and perhaps likely, the authors need to do a better job of accounting for fleet turnover, seasonal changes in NO₂ lifetime, etc.

We agree with the Reviewer that information about the change of the transport structure, as well as the influence of meteorological parameters would increase the value of the article, so we have added all the available information we founded and improved the text.

NOx emissions in newer car/trucks are lower than in older car/trucks, which implies that fleet turnover should lead to a decrease in NO_x emissions with time. How much did fleet turnover contribute to the reduction in concentrations between 2012 and 2016?

The age of a vehicle certainly has an impact on pollutant emissions, including NO₂, as newer models meet the increasingly rigorous EURO standards and pollute the environment to a lesser extent. However, the Polish car fleet has a very unfavorable age structure compared to other European countries with a significant share are old cars, which is shown in the table below:

 Passenger cars by age groups in 2012 and 2016 in Poland

 Although the data presented in the table concern the whole country, it illustrates the problem very well. It can be seen that during 4 analyzed years the number of new cars increased slightly (0.8%), the number of cars aged 3-15 decreased (8.7%), while the number of the oldest cars (> 16 years) increased (7.4%). In case of trucks and buses this structure is also unfavorable.

With such old vehicles, often in poor technical condition, it is difficult to suppose that 4 years of difference in the measurement period will have a significant impact on the observed changes in pollutant concentrations, due to the fleet turnover.

The lifetime of NO2 is shorter in the summer than in the spring. Thus, you would expect to see a decrease in NO2 concentrations between April-May and May-July. How much did the seasonal transition contribute to the decrease in concentrations between 2012 and 2016?

We have added some comment on the influence of meteorological parameters:

It is expected that meteorological parameters are interlinked in various ways with NO₂ levels in ambient air. However, it is difficult to assess the effect of each separate meteorological factor on NO₂ pollution. Studies involving analysis of NO₂ ambient levels as a function of meteorological parameters strongly depend on local factors (Voiculescu et al. 2020; Çelik and Kadi 2007; Dominick et al. 2012). According to (Elminir 2005), the NO₂ concentration is slightly higher at a lower relative humidity, whereas other authors found that the NO₂ concentration correlates positively with the relative humidity in all seasons, especially during winter (Gasmi et al. 2017). A negative correlation between wind speed and NO₂ concentration was found by (Zhou et al. 2014; Habeebullah et al. 2015; Hosseinibalam and Hejazi 2012). However, their analysis constructed by averaging pollutant concentration by wind speed use categories: 0–1 m/s, 1–2 m/s, etc. or ranges < 2m/s and >2m/s. As it can be seen the difference in humidity and wind speed is not significant. On the other hand, the difference in temperature between both sessions was 10.5°C. However, the relation between NO₂ and temperature is inconsistent. The correlation was found to be insignificant or weak (Day, Wooldridge, and Cohen 2008; Habeebullah et al. 2015), other studies found strong positive correlations between the NO₂concentration and temperature for all seasons (Gasmi et al. 2017). The research (Voiculescu et al. 2020; Kendrick, Koonce, and George 2015; Elminir 2005) underline, that the seasonal variation of NO₂ is only evident when compare summer/spring with fall/winter. Our intention was to avoid the measurements during the most dissimilar seasons.

NOx emissions per truck may be much larger than per car. What is the mix of diesel versus spark-ignited engines on these road? Did this ratio change when the road was built?

Unfortunately, we do not have data on the number and shares of cars with ZI and ZS engines on the DTS. In our opinion, the number of trucks for which the new-built DTS could have become more favourable than the A4 highway running on the city periphery (city ring road), which has been operating since 2005.

Engine idlling will contribute to high NOx emissions. How much was idling reduced by creation of the DTS.

The construction of the road, due to its highway character, allowed for the reduction of engine idling and the amount of stops and accelerations. Driving between the city borders in the east-west direction, in the old road system (until 2012) included 10 large intersections, including 8 with traffic lights and 1 railroad crossing. Currently, traffic on the DTS is very fluent and engine idling has been minimized.

Do you have traffic count information on these roads before and after construction of the DTS? Smoother traffic flow should contribute to lower concentrations.

At the end of 2013, the most modern traffic control system in Poland was launched in Gliwice, as part of which vehicle traffic intensity monitoring is carried out in selected points of the city. Thus, during the measurement period in 2012, the traffic in the city was not monitored. At present, traffic monitoring covers several measurement points in the city, including one in the DTS tunnel (mentioned in the Strengths and limitations).

L172: The temperature difference between periods (B) and (A) is over 10 degrees Celsius. What are the implications of these differences for NOx emissions and NOx lifetime? Emissions may vary with humidity too. How much did that change?

The average humidity changed but in a very small range 66.4% (B) and 66.8% (A). The fragment we which have added at the beginning of the Results section includes comments on meteorological parameters.

DTS was put into use in the second half of April 2016 (the commissioning date was rescheduled several times), which made it impossible to start measurements in the originally planned March date. Hence, there are differences in the values of meteorological parameters. For some parameters the differences are greater (temperature 10.5 degrees), for others smaller (wind speed: 0.4m/s; air humidity: 0.4% (average humidity 66.4% (B) and 66.8% (A)). On the basis of the archival meteorological data obtained from the website https://www.ekologia.pl/pogoda/polska/slaskie/gliwice/archiwum,zakres,22-04-2016_23-04-2016) (the State Environmental Monitoring does not make such data available), it can be concluded that carrying out measurements at the same dates, but in different years, does not provide the same meteorological conditions. For example, if the measurements in 2016 were made on the same days as the measurement series in 2012 (April-May), the mean temperature in this measurement period would be 4.8 degrees higher than the average temperature in the same period of 2012. This means that full coverage of measurement dates would not guarantee full comparability of results.

Much more problematic would be the execution of one of the series of measurements in the period from November to March, when the air quality in Gliwice is very significantly affected by the emission of pollutants from domestic furnaces and exceeds the emission from transport sources.

Of course, we agree with the Reviewer's comments that at higher air temperatures we can expect lower NO_xemissions from cars, as well as during the summer the NO₂ lifetime in the atmosphere is shorter, which may reduce its concentration in the air.

L172: NO2 concentrations near road ways are also sensitive to wind speed. Is the change in wind speed enough to matter?

In the above-mentioned fragment, we also included the wind speed influence. We can also include the role of 2 factors that could increase the concentration level by limiting the possibility of pollutants dispersion: the measurement period May-July 2016 (A) was characterized by lower wind speed than the period March-April 2012 (B) and in connection with the construction of DTS new barriers appeared in the field (e.g. high noise barriers). These two factors may to some extent offset the reduced NO₂ emission resulting from higher air temperatures.

L174: Why do you remove 4.4% of the observations? Couldn’t these be from cars/trucks in violation of air quality standards

The issue of removing 4.4% of the results is explained in great detail in response to note L165 (further on in response to the review). Removed results slightly decreased/increased mean concentration of 24h NO₂ calculated for a set of 3 samplers. The need to remove the results is imposed by the requirements of the standard (PKE 1989) and this step cannot be omitted in the determination of NO₂ concentrations using this method.

On the other hand, at none of points and in none of measurement series has any mean concentration been removed that would significantly affect the mean concentration values presented in Tables 1 and 2.

Minor Comments:

L16: will affect --- affected

L20/21 Suggest eliminating “contrary to the concerns of the residents”

L21/22: and an overall reduction of NO2 concentrations was observed --- and contributed to an overall reduction of NO2 concentrations

L23: low air quality --- poor air quality

Following the comments of the Reviewer 3 we have changed the abstract into (the new text includes above mentioned remarks):

Sustainable development requires ensuring the mobility of residents and must not cause deterioration of the quality of the environment in the selected area. The purpose of this study is to verify if the construction of a cross-regional highway through the city centre affected air quality in the neighbourhood of a newly-built road. Air quality has been assessed based on measurements of nitrogen dioxide concentrations, which is considered to be typical for automotive sources air pollution. The spectrophotometric method with passive sampling was used in the 24h NO₂ measurements. The calculated mean NO₂ concentrations in the periods before and after road construction are within the range: 23.2-31.9 μg/m³ and 22.3-28.9 μg/m³, respectively. The relative NO₂ concentrations determined in the study for 10 out of 11 sampling points are lower than the unity, including 5 points markedly lower (0.82 - 0.89). The obtained results indicate that the construction of the new artery by the city centre, using appropriate technical solutions and traffic organization (tunnel, noise barriers, roundabouts, speed limit) contributed to an overall reduction of NO₂ concentrations. The presented solution may serve as an example for other cities struggling with problems of low air quality associated with inefficient transportation systems.

L25: DTS is an acronym – perhaps expand

It has been deleted.

L28: cohesion --- cohesive

It has been corrected.

L58: Following the health threat --- To assess the health threat

It has been corrected.

L66: “Inevitable” may be too strong here. One can imagine a world where public transport dominates.

We have changed it into observed.

L101: Here and elsewhere, to minimize confusion, you may want to use the phrase “internal transportation system” as opposed to “internal communication system”.

We have changed communication into transportation in the text.

L103: What is the difference between “transit traffic” and “local traffic”? L107: caused the average --- resulted in an average

We meant that: Local traffic means the movement of vehicles within the city borders or in neighboring cities (the purpose of e.g. commuting to work, university, shopping; to the doctor, i.e. to take care of daily matters): while transit traffic means crossing the city (when there is no other road) to move further distances (usually transport of goods).

L105: runs through compact buildings with low traffic fluency, - runs past dense buildings and therefore has low traffic fluency,

It has been corrected.

L111: main communication --- main transportation

It has been corrected.

 L120: chosen solution in Gliwice has a length ... à chosen solution in Gliwice was a road of length 8.1 km that included (1), (2), and (3)

It has been corrected.

L165: I don’t understand what you are saying here. Differences of plus or minus 20% seem small. How many concentrations were taken from the 3 samplers. Would one expect the values to be the same? i.e., you need to convince me that you are not removing measurements from vehicles with no emission controls

According to the standard for NO₂ measurement in the air (PKE 1989) 3 passive samplers are hung for an each sampling point. After the sampling and spectrophotometric determination, the NO₂ concentration in the air is calculated for each of the 3 samplers (for each measurement at each sampling point, we obtain 3 concentration values from the 3 samplers hung there). From the obtained 3 concentrations the mean value is calculated (1 result), which is the NO₂ concentration determined at a given sampling point, under the condition that measurement errors (related to the mean) for all 3 determinations are not greater than 20%).

 Example:

If for any of the 3 results of the determinations the error is greater than the 20% standard, such a result must be rejected (red mark).

Example:

In our tests, the number of results that did not meet the condition (the error < 20%) was small and amounted to 4.4%, i.e. out of 561 results we had to reject 25. It is worth emphasizing that in our study it never happened, that the final result from 3 samplers had to be rejected.

As the Reviewer mentioned, the 20% difference does not seem to be big, but the rejection of the results is imposed by the standard.

L179: result pattern àresulting pattern

It has been corrected.

L197: Do you know how these near-road concentrations compare to concentrations at urban

areas away from roads?

The urban background concentrations in Gliwice determined in our other studies (sampling point located in the 2 city parks, were at range 7-12 mg/m³.

L224: referred to --- compared to

It has been corrected.

L285: “it can be concluded” --- This should be rephrased. You cannot conclude that the lower NO₂ concentrations are due to the 5 bullet points. Perhaps use “we conjecture that”

It has been corrected.

L307: By “road network” are you referring to roads that are not part of the DTS? If yes, make this clear.

Yes, as a “road network” we understand the roads other than DTS, which form the transportation system of the city.

We have added city road network beyond DTS.

 L320: Be clear as to what type of and how many roundabouts are along the DTS. Is there is only one type do not discuss the other type in this paragraph.

We have marked the roundabouts at Figure 2.

There are two turbo-roundabouts (listed in S1 at point 7) on the DTS, the construction of which undoubtedly improved the fluency of traffic on DTS and significantly improved the possibility of entering/exiting from DTS on DK88. This resulted in a significant reduction of concentrations in point 7, reaching 18% (the highest observed reduction). These roundabouts we marked in red in Figure 2 in the text.

In the vicinity of the DTS, there are also three additional conventional roundabouts which were built near the entry/exit roads. In Figure 2, they are marked in green.

We have marked the roundabouts at Figure 2.

 L333: multiline --- multi-lane

It has been corrected.

L388 Give units for 0.3.

It has been corrected.

Again, we would like to express our appreciation for your efforts and helpful comments. Enclosed, please find the revised version of our paper.

 Yours sincerely,

Anna Mainka and Magdalena Żak

 References:

Çelik, M Bahattin, and İbrahim Kadi. 2007. “The Relation Between Meteorological Factors and Pollutants Concentrations in Karabük City.” Journal of Science. Vol. 20. www.gujs.org.

Day, D. A., P. J. Wooldridge, and R. C. Cohen. 2008. “Observations of the Effects of Temperature on Atmospheric HNO 3 , ANs, PNs, and NO X : Evidence for a Temperature-Dependent HO x Source.” Atmos. Chem. Phys 8: 1867–79. www.atmos-chem-phys.net/8/1867/2008/.

Dominick, Doreena, Talib Latif, Hafizan Juahir, Ahmad Zaharin Aris, and Sharifuddin M Zain. 2012. “An Assessment of Influence of Meteorological Factors on PM and 10 NO at Selected Stations in Malaysia.” Sustain. Environ. Res22 (5): 305–15.

Elminir, Hamdy K. 2005. “Dependence of Urban Air Pollutants on Meteorology.” Science of the Total Environment 350 (1–3): 225–37. https://doi.org/10.1016/j.scitotenv.2005.01.043.

Gasmi, Khaled, Abdulaziz Aljalal, Watheq Al-Basheer, and Mumin Abdulahi. 2017. “Analysis of NOx, NO and NO2 Ambient Levels as a Function of Meteorological Parameters in Dhahran, Saudi Arabia.” WIT Transactions on Ecology and the Environment 211 (2): 77–86. https://doi.org/10.2495/AIR170081.

Habeebullah, Turki M., Said Munir, Awad bdel Hameed A. A., Essam A. Morsy, Seroji Abdulaziz R., and Atif M. F. Mohammed. 2015. “The Interaction between Air Quality and Meteorological Factors in an Arid Environment of Makkah, Saudi Arabia.” International Journal of Environmental Science and Development 6 (8): 576–80. https://pdfs.semanticscholar.org/359f/985d8a7cca629f91511bf3423b6c43072c9b.pdf.

Hosseinibalam, Fahimeh, and Azadeh Hejazi. 2012. “Influence of Meteorological Parameters on Air Pollution in Isfahan.” In 3rd International Conference on Biology, Environment and Chemistry, 7–12. https://doi.org/10.7763/IPCBEE. 2012.

Kendrick, Christine M, Peter Koonce, and Linda A George. 2015. “Diurnal and Seasonal Variations of NO, NO 2 and PM 2.5 Mass as a Function of Traffic Volumes alongside an Urban Arterial.” Atmospheric Environment 122 (December): 133–41. https://doi.org/10.1016/j.atmosenv.2015.09.019.

PKE. 1989. PN-Z-04009-08: Air Purity Protection, Tests for Nitric Acid and Nitrogen Oxides. Determination of Nitrogen Dioxide in Ambient Air (Imision) by Spectrophotometric Method with Passive Sampling.https://sklep.pkn.pl/pn-z-04009-08-1989p.html.

Voiculescu, Mirela, Daniel-Eduard Constantin, Simona Condurache-Bota, Valentina Călmuc, Adrian Roșu, and Carmelia Mariana Dragomir Bălănică. 2020. “Role of Meteorological Parameters in the Diurnal and Seasonal Variation of NO2 in a Romanian Urban Environment.” International Journal of Environmental Research and Public Health 17 (17): 6228. https://doi.org/10.3390/ijerph17176228.

Zhou, Rui, Shanshan Wang, Chanzhen Shi, Wenxin Wang, Heng Zhao, Rui Liu, Limin Chen, and Bin Zhou. 2014. “Study on the Traffic Air Pollution inside and Outside a Road Tunnel in Shanghai, China.” Edited by Yinping Zhang. PLoS ONE 9 (11): e112195. https://doi.org/10.1371/journal.pone.0112195.

Author Response File: Author Response.pdf

Reviewer 3 Report

This study is about cross-regional highway built through a city center as an example of the sustainable development of urban transport. I have some detailed comments below to help improving the manuscript.

1, the abstract should list some specific results as take away message for readers. The main conclusion, some quantifications, highlight, unique results should be addressed in abstract.

2, Some discussion could be added in the last section. Some limits of this study, differences or similarity between this study and other studies should be elaborated.  

Author Response

November 15, 2020

Manuscript ID: sustainability-999898

Title: "Cross-Regional Highway built through a city centre as an example of the sustainable development of urban transport"

 Response to the comments of Reviewer 3

 We appreciate your response and the helpful suggestions for improving the presentation of our study. We have detailed our modifications as they relate to your comments on the original manuscript.

1. The abstract should list some specific results as take away message for readers. The main conclusion, some quantifications, highlight, unique results should be addressed in abstract.

We have corrected the abstract concerning remarks mentioned above and keeping the limit of 200 words:

Sustainable development requires ensuring the mobility of residents and must not cause deterioration of the quality of the environment in the selected area. The purpose of this study is to verify if the construction of a cross-regional highway through the city centre affected air quality in the neighbourhood of a newly-built road. Air quality has been assessed based on measurements of nitrogen dioxide concentrations, which is considered to be typical for automotive sources air pollution. The spectrophotometric method with passive sampling was used in the 24h NO₂ measurements. The calculated mean NO₂ concentrations in the periods before and after road construction are within the range: 23.2-31.9 μg/m³ and 22.3-28.9 μg/m³, respectively. The relative NO₂ concentrations determined in the study for 10 out of 11 sampling points are lower than the unity, including 5 points markedly lower (0.82 - 0.89). The obtained results indicate that the construction of the new artery by the city centre, using appropriate technical solutions and traffic organization (tunnel, noise barriers, roundabouts, speed limit) contributed to an overall reduction of NO₂ concentrations. The presented solution may serve as an example for other cities struggling with problems of low air quality associated with inefficient transportation systems.

2. Some discussion could be added in the last section. Some limits of this study, differences or similarity between this study and other studies should be elaborated.

We have added the following fragment at the last section:

Burns et al. (Burns et al. 2020), in the comprehensive review, presented four groups of interventions to reduce ambient air pollution and their effects on human health (industrial, residential, multiple and vehicular). Among vehicular interventions implemented in the cities to reduce ambient air pollution the infrastructure changes or road reconstructing represent one of the seven groups. The other transport-related interventions included speed limit change, low emission zone, even-odd restriction, charging scheme, public transport restructuring and comprehensive traffic reduction strategy. The first infrastructure intervention (Titos et al. 2015) included closing and a reconstruction of a 400 m of the street in the centre of Ljubljana municipality for all traffic except public buses and taxis as an abatement measure. In compare to our intervention, it is much smaller and did not result in significant improvement in NO₂concentrations, the NO₂ reduction was from 29 to 27 mg/m³. The second intervention (Cowie et al. 2012) included building 3.6 km tunnel linking two major roadways, along with concomitant road changes to a nearby main road to reduce traffic, including lane number reduction and a dedicated bus lane. The study (Cowie et al. 2012) from 2006 to 2008 showed that the tunnel intervention resulted in 8.1% reduction of NO₂ concentration, so comparable to our results. The third intervention (Burr et al. 2004) included the opening of the by-pass road. The authors underline that the opening of the by-pass led to a reduction in atmospheric pollution in the congested streets, with a proportionate reduction of the lower concentrations in the uncongested streets. However, their research was based on PM₁₀ and PM_2.5 reduction.

 Moreover, our study doesn’t include the period of DTS construction. Some studies underline the environmental impact of greenhouse gasses (GHG), particularly CO₂, as well as NO_x and PM which were generated during highway or tunnel construction works (Hajji et al. 2019; Wang et al. 2015; Ma et al. 2016).

Again, we would like to express our appreciation for your efforts and helpful comments. Enclosed, please find the revised version of our paper.

 Yours sincerely,

Anna Mainka and Magdalena Żak

 References:

Burns, J., H. Boogaard, S. Polus, L. M. Pfadenhauer, A. C. Rohwer, A. M. van Erp, R. Turley, and E. A. Rehfuess. 2020. “Interventions to Reduce Ambient Air Pollution and Their Effects on Health: An Abridged Cochrane Systematic Review.” Environment International. Elsevier Ltd. https://doi.org/10.1016/j.envint.2019.105400.

Burr, M. L., G. Karani, B. Davies, B. A. Holmes, and K. L. Williams. 2004. “Effects on Respiratory Health of a Reduction in Air Pollution from Vehicle Exhaust Emissions.” Occupational and Environmental Medicine 61 (3): 212–18. https://doi.org/10.1136/oem.2002.003244.

Cowie, Christine T., Nectarios Rose, Robert Gillett, Scott Walter, and Guy B. Marks. 2012. “Redistribution of Traffic Related Air Pollution Associated with a New Road Tunnel.” Environmental Science and Technology 46 (5): 2918–27. https://doi.org/10.1021/es202686r.

Hajji, A. M., A. Yulistyorini, Huang Yue, and D. C. Patulak. 2019. “Emission Factors of NOx and PM of Heavy Construction Equipment Used in Toll Road Project in Indonesia - Case Study: Rembang-Pasuruan Toll Section II.”IOP Conference Series: Materials Science and Engineering 669 (1). https://doi.org/10.1088/1757-899X/669/1/012003.

Ma, Feng, Aimin Sha, Ruiyu Lin, Yue Huang, and Chao Wang. 2016. “Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China.” International Journal of Environmental Research and Public Health 13 (3): 351. https://doi.org/10.3390/ijerph13030351.

Titos, G., H. Lyamani, L. Drinovec, F. J. Olmo, G. Močnik, and L. Alados-Arboledas. 2015. “Evaluation of the Impact of Transportation Changes on Air Quality.” Atmospheric Environment 114 (August): 19–31. https://doi.org/10.1016/j.atmosenv.2015.05.027.

Wang, Xianwei, Zhengyu Duan, Lingsheng Wu, and Dongyuan Yang. 2015. “Estimation of Carbon Dioxide Emission in Highway Construction: A Case Study in Southwest Region of China.” Journal of Cleaner Production 103 (September): 705–14. https://doi.org/10.1016/j.jclepro.2014.10.030.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

See attached review. 

Comments for author File: Comments.pdf

Author Response

November 24^th, 2020

Manuscript ID: sustainability-999898

Title: "Cross-Regional Highway built through a city centre as an example of the sustainable development of urban transport."

 Response to the comments of Reviewer 2

 Thank you for giving us the opportunity to submit a revised draft of our manuscript. We appreciate the time and effort that you have dedicated to providing your valuable feedback on our manuscript. We have been able to incorporate changes to reflect most of the suggestions provided by the reviewers. We have highlighted the changes within the manuscript in yellow.

Here is a point-by-point response to your comments and concerns.

1. The authors conclude that an observed reduction in NOx concentrations is due to construction of a bypass highway through a city center. While plausible and perhaps likely, the authors need to do a better job of accounting for the impact of seasonal changes in NO2 lifetime and changes in fleet composition on the observed NO2.

Thank you for this suggestion. It would have been interesting to explore this aspect. However, in the case of our study, it seems slightly out of scope because: The lifetime of NO₂ is from between 1 and 2 days. The relatively short lifetime at the surface is a result of the fact that most of the NO_x is in the form of NO₂ at the surface, and the OH + NO₂ reaction dominates the lifetime of NO_x. During daytime, NO and NO₂ interconvert by the photochemical NO_x cycle. At night, NO₂ does not photolyze, and, as a result, the chemistry of the NO_x family is different between daytime and nighttime. However, in case of the 24h measurements it doesn’t have impact on NO₂ average levels. We have added comments that significant seasonal changes in NO₂ levels occur between the winter and summer seasons. The relationships between the other seasons may vary depending on the location. In our research we intentionally selected the season apart from the heating period, as the low emission from municipal sources is particularly influential.

2. In the main text, you need to support your hypothesis that NOx emissions per km of the 2016 fleet was the same or more as that of the 2012 fleet. In what year(s) was the EURO NOx emission standards made more rigorous? What percent of the vehicle fleet was made before/after that date in 2012 and 2016?

The following fragment has been added to the text:

It can be assumed that the reduction of concentrations measured in 2016 compared to 2012 may be influenced not only by the actions presented earlier (construction of DTS with the whole infrastructure), but also by the change of the vehicle fleet during these four years. The age of a vehicle certainly has an impact on pollutant emissions, including NO₂, as newer models meet the increasingly rigorous Euro standards and pollute the environment to a lesser extent. Euro 6 standard valid form September 2015 enforced a significant reduction of NO_x from diesel engines (ZS) (a 67% reduction) compared to Euro 5, while for petrol ones (ZI) the standard had not been exacerbated (Automobile Association 2020). However, the Polish car fleet has a very unfavorable age structure compared to other European countries with a significant share are old cars. During four analyzed years the number of new cars increased slightly (0.8%), the number of cars aged 3-15 decreased (8.7%), while the number of the oldest cars (> 16 years) increased (7.4%). In case of trucks and buses this structure is also unfavorable (Statistics Poland 2017; 2013). With such old vehicles, often in poor technical condition, it is difficult to suppose that 4 years of difference in the measurement period will have a significant impact on the observed changes in pollutant concentrations, due to the fleet turnover.

3. The lifetime of NO2 is shorter in the summer than in the spring. Thus, you would expect to see a decrease in NO2 concentrations between April-May and May-July. The section you added confuscates rather than illustrates. How do the 2016 concentrations vary between May and July? How do the May 2012 and May 2016 concentrations compare?(Check out recent COVID- 19 papers by for e.g., Debora Griffin (GRL) and Dan Goldberg (GRL)

Concentration change [%] between May 2016 and July 2016 (with reference to May 2016)

Concentrations at three measurement points in July were lower than in May (between 0.2 and 7.4%; mean 3.5%). at other points higher (0.4 and 28.6%; mean 8.8%)

Concentration change [%] between May 2012 and May 2016 (with reference to May 2012)

In five sampling points, the concentrations in May 2016 were higher than in May 2012 (between 2.5 and 19.3%; average 10.9%), in the remaining six points, concentrations were lower (0.5 and 34.3%; average 8.3%).

Yes, the mean the lifetimes are found to be shorter in summer compared to spring but the difference is between 3.2h and 4.2h, respectively (Liu et al. 2016) in our opinion during 24h measurements this difference is not influential.

We checked out the mentioned publication (Goldberg et al. 2020): “Accounting for natural NO₂ fluctuations are especially important during spring, a time when the NO₂ concentrations and lifetimes are quickly changing due to transitioning meteorology, solar zenith angle, and snow cover”. However, the authors do not put any references to confirm it, moreover their results as they compare 2019 with 2020 (the COVID lockdown) also do not confirm such a statement.

4. You should mention that NOx emissions per truck may be much larger than per car but that information on the mix of diesel versus spark-ignited engines on the DTS and surrounding roads is unavailable. You could also speculate that the new highway is moving a percentage of trucks off of the loal roads.

The following fragment has been added to the text:

The limitation of the presented data in the article is the lack of information on the change of shares of cars and trucks moving on DTS and surrounding roads in the period before and after the construction of this road, but such data are not available. Such information would be valuable in analyzing the impact of a possible change of cars and trucks shares on the NO₂ levels, because, as the literature data indicate NO_x truck emissions are much larger than car emissions (Quiros et al. 2016; Velders, Geilenkirchen, and de Lange 2011).

5. Engine idlling will contribute to high NOx emissions. How much was idling reduced by creation of the DTS. You could include this information in your main body.

The following fragment has been added to the text:

Moreover, the construction of the road, due to its highway character, allowed for the reduction of engine idling and the amount of stops and accelerations. Driving between the city borders in the east-west direction, in the old road system (until 2012) included 10 large intersections, including 8 with traffic lights and 1 railroad crossing. Currently, traffic on the DTS is very fluent and unfavourable operating conditions for has been minimized.

Other Comments:

L22 “contributed to an overall reduction” - You have not shown this ... To show this you need to assess the impact of seasonality and fleet turnover.

We have changed contributed into influenced the reduction.

L66: correct typo – observed

It has been corrected.

L81: I would move the first sentence to the beginning of the next paragraph. I would modify the next few sentences as follows and take it onto the end of the preceding paragraph.

It has been corrected.

L82 On the other hand ... high investments. ----
Since a change in traffic policy requires a high investment, research demonstrating the likely positive environmental effect of any investment is needed.

It has been corrected.

L118: road surfaces are often --- road surfaces, often

It has been corrected.

L118/119: in an average transportation speed --- in average speeds

It has been corrected.

L134 or (3) --- and (3)

It has been corrected.

L183: humidity --- relative humidity

It has been corrected.

L193: As it can be seen the difference in humidity and wind speed is not significant --- As can be seen, differences in humidity and wind speed between the periods are not significant

It has been corrected.

L198: There may be a substantial seasonal variation in NO2 between the spring and summer.

We didn’t find confirmation for this statement. But we have added:

…and although, the mean lifetimes of NO₂ are found to be shorter in summer compared to spring but the difference is between 3.2h and 4.2h, respectively (Liu et al. 2016) so during 24h measurements the difference is not influential.

L202: State that removal of outliers is not expected to affect the results?

We have added the information in the text.

L356: Do you mean “multi-lane”?

Yes, it has been corrected.

L407: in the --- in a

It has been corrected.

L409: ambient air pollution of the infrastructure changes --- ambient air pollution, infrastructure changes

It has been corrected.

L415: In compare --- In comparison

It has been corrected.

L424-427: How long did the construction take?

The following information has been added to the text:

January 2013 – March 2016 (construction); April 2016 putting into use

 We look forward to hearing from you in due time regarding our submission and to respond to any further questions and comments you may have.

 with regards,

Anna Mainka and Magdalena Żak

 References:

Automobile Association. 2020. “Euro Emissions Standards.” 2020. https://www.theaa.com/driving-advice/fuels-environment/euro-emissions-standards.

Goldberg, Daniel L., Susan C. Anenberg, Debora Griffin, Chris A. McLinden, Zifeng Lu, and David G. Streets. 2020. “Disentangling the Impact of the COVID‐19 Lockdowns on Urban NO ₂ From Natural Variability.” Geophysical Research Letters 47 (17). https://doi.org/10.1029/2020GL089269.

Liu, Fei, Steffen Beirle, Qiang Zhang, Steffen Dörner, Kebin He, and Thomas Wagner. 2016. “NO x Lifetimes and Emissions of Cities and Power Plants in Polluted Background Estimated by Satellite Observations.” Atmos. Chem. Phys 16: 5283–98. https://doi.org/10.5194/acp-16-5283-2016.

Quiros, David C., Arvind Thiruvengadam, Saroj Pradhan, Marc Besch, Pragalath Thiruvengadam, Berk Demirgok, Daniel Carder, Adewale Oshinuga, Tao Huai, and Shaohua Hu. 2016. “Real-World Emissions from Modern Heavy-Duty Diesel, Natural Gas, and Hybrid Diesel Trucks Operating Along Major California Freight Corridors.” Emission Control Science and Technology 2 (3): 156–72. https://doi.org/10.1007/s40825-016-0044-0.

Statistics Poland. 2013. “Environment 2013.” 2013. https://stat.gov.pl/obszary-tematyczne/srodowisko-energia/srodowisko/ochrona-srodowiska-2013,1,14.html.

Statistics Poland. 2017. “Environment 2017.” 2017. https://stat.gov.pl/obszary-tematyczne/srodowisko-energia/srodowisko/ochrona-srodowiska-2017,1,18.html.

Velders, Guus J.M., Gerben P. Geilenkirchen, and Ronald de Lange. 2011. “Higher than Expected NOx Emission from Trucks May Affect Attainability of NO2 Limit Values in the Netherlands.” Atmospheric Environment 45 (18): 3025–33. https://doi.org/10.1016/j.atmosenv.2011.03.023.

Reviewer 3 Report

This version is fine.

Author Response

November 24^th, 2020

Manuscript ID: sustainability-999898

Title: "Cross-Regional Highway built through a city centre as an example of the sustainable development of urban transport."

 Response to the comments of Reviewer 3

 We appreciate your response. Thank you for your time to check our article for the second time and the acceptance of the improvements.

 with regards,

Anna Mainka and Magdalena Żak

 Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

See Attached

Comments for author File: Comments.pdf

Author Response

November 27^th, 2020

Manuscript ID: sustainability-999898

Title: "Cross-Regional Highway built through a city centre as an example of the sustainable development of urban transport."

 Response to the comments of Reviewer 2

 Thank you for your time and effort that you have dedicated to providing your valuable feedback on our manuscript. We have included all the remarks which you have underlined, and highlighted the changes within the manuscript in pink. As the lines in your review didn’t fit to the manuscript from the system, we have added the corresponding numbers of lines.

Here is a point-by-point response to your comments and concerns.

 Cross-Regional Highway …

Main Comments: The authors conclude that an observed reduction in NOx concentrations is due to construction of a bypass highway through a city center. The results of this study are consistent with that hypothesis; however, the 2012 and 2016 measurement periods do not coincide making it impossible to make a definitive conclusion given that May 2012 and May 2016 concentrations were similar as noted in the response to comments. Thus, on L64 the authors must use “likely contributed to an overall reduction in NO2 concentrations” as opposed to “contributed to an overall reduction in NO2 concentrations”.

We have added “likely” in the text. In the manuscript it is the line 22.

L321-326: This section is poorly written and confusing. Consider going with … … The lifetime of NO2 decreases from 4.2 to 3.2 hours between the spring and summer [47]. Thus, on average, afternoon concentrations of NO2 are less in the summer than in the spring. However, the NO2 concentrations used in this study are 24-hour averages, which are less affected by the change in lifetime, which is driven by seasonal changes in daytime OH concentrations.

The above-mentioned remarks have been added in the text - lines 201 -205. 

 General Comments:

L64: I believe your original text is better although you need to add the modifier “likely”.

Thus, go with “likely contributed to a reduction in NO2 concentrations”.

It has been corrected (line 22-23)

Grammatical Corrections and/or Modifications

L126: the modelling tools --- modelling tools   

It has been corrected (line 84).

L192: result in an average --- result in average 

It has been corrected (line 119)

L214-215: Is this better? The two turbo-roundabouts at one sampling point are shown in red while conventional roundabouts are shown in green  

It has been corrected (line 136-138)

L318: The use of “not significant” implies a statistical test. I suggest replacing “not significant’ with “small” or “small and likely insignificant”.  

It has been corrected (line 196)

L330: doesn’t affect --- doesn’t materially affect  

It has been corrected (line 209)

L510-511 Replace “ From the changes of concentration described, we can conjecture that a positive effect of DTS construction in the city centre on ambient air quality was possible according to four factors:” with “We now explore the role five factors played in the improved air quality after construction of the DTS:”   

It has been corrected (line 316-317)

L637: a significant share are --- a significant share of  

It has been corrected (line 394)

L677: operating conditions for has been minimized --- operating conditions have been minimized 

It has been corrected (line 434)

L696: The limitations of the study are that the article focuses --- A limitation of this study is that it focuses  

It has been corrected (line 453)

L697: form January --- from January

It has been corrected (line 455)

L706: The other limitation --- Another limitation 

It has been corrected (line 463)

L732: who expressed many doubts --- who previously expressed doubts 

It has been corrected (line 489).

 We look forward to hearing from you in due time regarding our submission and to respond to any further questions and comments you may have.

 with regards,

Anna Mainka and Magdalena Żak