Environmental impacts from the construction and maintenance of a motorway in Greece

Transcription

1 Environmental impacts from the construction and maintenance of a motorway in Greece G.I. Angelopoulou a, C. J. Koroneos b, M. Loizidou c a National Kapodistrian University of Athens Physics Department University Campus at Zografou, Athens giaggel@gmail.com b Laboratory of Heat Transfer and Environmental Engineering Aristotle University Thessaloniki, GR-54124, Thessaloniki, Greece koroneos@aix.meng.auth.gr, c National Technical University of Athens/ School of Chemical Engineering Department of Chemical Sciences GR , Zographou Campus, Greece mloiz@orfeas.chemeng.ntua.gr Introduction Abstract The environmental impacts as result of a motorway construction vary according to the plurality of tasks and the acquisition of the materials. In order to allocate those impacts we applied the Life Cycle Analysis (LCA) method in the construction and maintenance of a motorway in Greece. Actual data were used, from constructing the first free motorway in Greece. The total studied length of the motorway is one hundred (100) kilometres, with three (3) lanes per direction. The assumed duration of the construction is 48 months, with obligation of maintenance on the seventh and fifteenth year of use. The amplitude of the project forced us to narrow the construction tasks in embankments, excavations and cleansings, earthworks, basic flood-preventing works, pavement and bisector island construction, and finally road marking. The used materials were limited in the production of limestone and slug aggregates, asphaltic bitumen, concrete and color. Also all transports were taken into consideration. Finally we took into consideration only air pollutants emitted by the consumption of electric energy and fuels. The results of the above mentioned methodology can be used as a guide, within the use of our model. This model gives the ability to the user to calculate the environmental impacts of a motorway construction and maintenance. The minimum necessary inputs are the length of the motorway, the number of the lanes per direction and the desirable constructing duration. The main outputs are the required materials, the number and kind of machines, the material production units and the environmental impacts. Life Cycle Assessment (LCA) is an investigation and valuation tool of the environmental impacts of a given product or service caused or necessitated by its existence. The goal of LCA is to compare the full range of environmental damages assignable to products and services, in order to be able to choose the least burdensome one. 1

2 The term 'life cycle' refers to the notion that a fair, holistic assessment requires the assessment of raw material production, manufacture, distribution, use and disposal including all intervening transportation steps necessary or caused by the product's existence. The sum of all those steps - or phases - is the life cycle of the product. Common categories of assessed damages are global warming (greenhouse gases), acidification, smog, ozone layer depletion, eutrophication, eco-toxicological and human-toxicological pollutants, desertification, land use as well as depletion of minerals and fossil fuels. A Life Cycle Assessment is carried out in four distinct phases. Goal and scope - In the first phase, the LCA-practitioner formulates and specifies the goal and scope of study in relation to the intended application. Life cycle inventory - The second phase involves data collection and modeling of the product system, as well as description and verification of data. Life cycle impact assessment - The third phase 'Life Cycle Impact Assessment' is aimed at evaluating the contribution to impact categories such as global warming, acidification, etc. Interpretation - The last phase stage is the most important one, as it s an analysis of major contributions, sensitivity analysis and uncertainty analysis leads to the conclusion whether the ambitions from the goal and scope can be met. Therefore the LCA method is a quantification tool of the direct and indirect effects of products and processes to the environment. With time the method has developed and the application fields have been multiplied. The last decade there is an increasing interest among construction companies to use the method in order to decide the construction processes type and materials. Road construction and maintenance The construction of road includes a variety of works, such as excavations, surfacing, storm drainage systems, pavement works and electromechanical works. The life duration of a highway depends from circulatory, as well as from the methodology of maintenance where sometimes whole parts of the road need reconstruction. During the earth works and after the alignment of the road surface, which includes cross slope, banking, superelevation, horizontal and vertical curvature, follows the surfacing works where limestone aggregates 3A type are layered. The lightly wet aggregates are transferred by heavy duty tracks to the working area where they are layered with finishers and finally compacted with soil compactors. Afterwards the working area is left to dry a few days before the paving works begin. Every layer of asphalt concrete cannot be thicker than 7-8cm and between every layer intercalates an asphalt emulsion layer. The asphalt concrete is layered with a paver, followed by two vibratory compactors and one pneumatic tire compactor. The total thickness of the surfacing and the pavement is relative to the type of the ground and the usage of the road. The amount and the kind of the machines are depended to the width and the length of the road, the type of soil, the construction deadline, the weather conditions and many other factors. For the above reasons we chose as an example of a 100Km long motorway, with three lanes per direction and four years duration of construction. We also assumed that the 2

3 soil is soft and that there are no bridges, tunnels or cut and covers. Furthermore we assumed that the designs demand the manufacture a 250mm thickness pavement, an asphalt layer of 130mm thickness and moreover a layer of antiskid asphalt with 40mm thickness. The duration of construction is proximately 208 weekday days per year, taking into consideration meteorological conditions and the by any chance problems that may occur. All the works do not start or finish at the same time but most of them depend from the others (Table 1). In order to construct the motorway we must use a variety of heavy duty and special machines. For our example we chose to use three plants of asphalt production and one plant of aggregate production and we assumed that the plants are stationed near the working area hence the trucks cover an average distance of 25km per day. Description Groundfill/ Purification works 1 st year 2 nd year 3 rd year 4 th year Months % Months % Months % Months % 4,80 100% 0,00 0% 0,00 0% 0,00 0% Earthwoks 7,20 33% 12,00 56% 2,40 11% 0,00 0% Drainage works etc 0,00 0% 0,00 0% 9,60 67% 4,80 33% Pavement & Asphalt works 0,00 0% 0,00 0% 0,00 0% 7,20 100% Table 1: Construction Timetable After the completeness of the project the road is given to the public for use, but as any other product must have routine and scheduled maintenance. It is most common for a motorway to have the first (mild) maintenance after 7 or 8 years of use and the second (heavy) maintenance after 15 years of use. During the first maintenance we will have to replace the antiskid asphalt layer and during the second one we will have to also replace the total of the asphalt layer. LCA of a road By applying the LCA Method during the construction and maintenance of a motorway we have the opportunity to choose the appropriate materials in order to create a more durable and cheaper product, with longer life and less environmental impact. The analysis of the life of a road network comprises all the main construction stages Fig.1 LCA of a road during construction and maintenance, including the production and carriage of the main materials. We studied the product as a hole because the choice of one material affects the other materials and also the construction method as well the maintenance depth. The description of total of environmental effects of activities and products, should become in such a way that the alternative solutions they can be compared to choice of suitable. In our study we narrowed the items of the works in earthworks, pavement, drainage, asphalt works, safety zone and finally crosshatching. All the used data are from the construction of the Attiki Odos, which is a free motorway in Greece and from the involved industry. For our calculations (Error! Reference source not found.) we have taken into consideration the daily output of the machines, their medium daily operation and the usual meteorological conditions during the year. All these information were used for the development of a model 3

4 which with minimum inputs the length of the motorway, the number of the lanes per direction and the desirable constructing duration calculates the required materials, the number and kind of machines, the material production units and the environmental impacts. The application gives the ability to the user to add information about the project and change factors or parameters. Fig.1 LCA of a road during construction and maintenance During the Construction Period CO 2 ROG CO NO x SO 2 PM 10 Earthworks/Pavement ,613 0,204 0,753 1,820 0,000 0,154 Drainage network 14,974 0,012 0,042 0,121 0,001 0,005 Asphalt concrete 7.927,673 0,080 1,360 9,692 11,442 0,025 Cross-hatching 6,595 0,000 0,001 0,003 0,000 0,000 Bisector island 13,114 0,002 0,005 0,003 0,002 0,000 Total (tons) ,97 0,2975 2, , ,4454 0,1849 During the First Maintenance CO 2 ROG CO NO x SO 2 PM 10 Asphalt concrete 1.518,31 0,0336 0,4801 3,2985 3,8148 0,0051 Cross-hatching 6,60 0,0003 0,0010 0,0030 0,0000 0,0001 Total (tons) 1.524,90 0,0339 0,4811 3,3016 3,8148 0,0052 During the Second Maintenance CO 2 ROG CO NO x SO 2 PM 10 Asphalt concrete 7.903,49 0,0509 1,2725 9, ,4420 0,0138 Cross-hatching 6,60 0,0003 0,0010 0,0030 0,0000 0,0001 Total (tons) 7.910,08 0,0512 1,2735 9, ,4420 0,0139 Table 2 Emissions per 1Km constructed road 4

5 The repercussions in the environment, in which we chose to focus, are the greenhouse effect, the acid rain, the eutrophication and the smog. In any case contributes one or more of the emitted gases. Using equivalent factors Table 3 - Equivalent factors for each gas, we quantify the potential repercussions in the environment and calculate the equivalent quantities Table 4 - Equivalent quantities Kg/Kg of each emitted gas, for every construction stage. Equivalent factors Gas Greenhouse effect Acid Rain Eutrophication Smog CO 2 1,000 ROG 0,398 CO 1,000 NO x 0,700 0,130 SO 2 1,000 1,000 PM 10 1,000 Table 3 - Equivalent factors During the Construction Period CO 2 SO 4 PO 4 SMOG CO ,35 ROG 118,42 CO 2.160,91 NO x 8.146, ,98 SO , ,38 PM ,87 Total Quantities , , , ,66 During the First Maintenance CO 2 SO 4 PO 4 SMOG CO ,72 ROG 13,49 CO 481,10 NO x 2.311,10 429,20 SO , ,79 PM 10 5,18 Total Quantities , ,89 429, ,47 During the Second Maintenance CO 2 SO 4 PO 4 SMOG CO ,57 ROG 20,37 CO 1.273,51 NO x 6.612, ,04 SO , ,98 PM 10 13,90 Total Quantities , , , ,26 Table 4 - Equivalent quantities Kg/Kg 5

6 Via the factors of normalization and assessment it is possible to connect all values of repercussions with a situation of report and with this way to be realised witch work contributes more and receive a total price of repercussion for each material and activity Error! Reference source not found. Fig. 2~ Fig. 7). During the Construction Period Impact Normalization factors Normalized values Assessment factors Assessment values Greenhouse effect 0, , , ,30616 Acid Rain 0, , ,78632 Eutrophication 0, , ,20018 Smog 0, , ,67915 During the First Maintenance Impact Normalization factors Normalized values Assessment factors Assessment values Greenhouse effect 0, , ,5 282,95907 Acid Rain 0, , ,97885 Eutrophication 0, , ,22566 Smog 0, , ,17393 During the Second Maintenance Impact Normalization factors Normalized values Assessment factors Assessment values Greenhouse effect 0, , , ,55637 Acid Rain 0, , ,24240 Eutrophication 0, , ,87388 Smog 0, , ,24152 Table 5 Normalized and Assessment Values Fig. 2 Normalized values during the construction Fig. 3 Normalized values during the first maintenance 6

7 Fig. 4 Normalized values during the second maintenance Fig. 5- Assessment values during the construction Fig. 6 - Assessment values during the first maintenance Fig. 7 - Assessment values during the second maintenance During the construction of the road, as it was expected, the more important environmental repercussion is the aid of the greenhouse effect, followed from the acidic rain, the smog and the phenomenon of eutrophication. On the contrary during the last year of construction Table 1and the maintenance, the more important repercussion is the acidic rain and this because basic source of pollutants is the production of asphaltic concrete which is based on petroleum (Table 6, Figure 8). The repercussions to the environment and the harmful effects to perhaps living areas are more important as shorter is the timetable of the works and this because the volume of emissions remains the same. 4 th year of construction Impact Normalization factors Normalization value Assessment factors Assessment value Greenhouse effect 0, , , ,34660 Acid Rain 0, , ,80484 Eutrophication 0, , ,47248 Smog 0, , ,49018 Table 6 Normalized and Assessment Values of the last year of construction Figure 8 - Assessment values during the last (forth) year of construction 7

8 CONCLUSIONS Big constructions cause repercussions in the natural environment not only by changing the natural landscape and the biotopes but also by polluting the air and the ground. As it was expected, the manufacture of a motorway strengthens the greenhouse effect. The CO 2 emissions are particularly high and by 99% come from the electric current consumption for the aggregate production. The nature of the materials is the one that dictates the use of powerful machines with big horsepower. In Greece the production of electric current is mostly based in fossil fuels hence the solution would be the consumption of electric current produced from renewable sources of energy. Unfortunately the NO x and SO 2 emissions, which contribute in the creation of acidic rain and smog, mostly come from the asphaltic concrete production, the refineries and the color production industry. Those emissions cannot be avoided because of the way we construct roads, but they can be decreased by making more environmental friendly industries and by developing methods of replacing the petroleum. Each human activity has certain repercussions in the environment, small or big, positive or negative, direct or indirect. More specifically the activities that concern the use of natural resources have important repercussions in the natural environment, which can be multiplied or decreased, depending on the solutions that are selected for the confrontation of problems. The existence of environmental repercussions does not require suppression of human activities; neither however can the necessity of work justify any intervention in the environment. REFERENCES Nikolaides Ath. - Road construction and materials Ch. I. Efremides - Structural machines Kofitsas I. D. Road construction A.Prapides, G. Doulis, V. Zotiades Slag usage in asphaltic concrete production based on mechanic and environmental criteria Caterpillar Performance Handbook 37 edition Mary Ann,Curran - Environmental Life-cycle Assessment (McGraw-Hill Education) Jeannette Sjunnesson - Life Cycle Assessment of Concrete (Ph.D., LUND University 2005) Harpa Birgisdóttir - Life cycle assessment model for road construction and use of residues from waste incineration (Ph.D. Thesis, Technical University of Denmark, 2005) Τ. H. Christensen and M. Z. Hauschild (Technical University of Denmark) - A model for life cycle assessment of road construction and disposal of Residues Τ. H. Christensen and M. Z. Hauschild (Technical University of Denmark) - Life cycle assessment of disposal of residues from waste incineration. R.J. Peploe, Bartley Consultants Ltd, New Zealand and A. Dawson, University of Nottingham - «Environmental Impact of Industrial By-products in Road Construction P. O.Nelson, P. Thayumanavan, M. F.Azizian, and K. J.Williamson - Evaluation Methodology for Environmental Impact Assessment of Industrial Wastes Used as Highway Materials Informations Dr V. Sagias Mech. Eng, Ν.Μ. Gavalas SA Mr G. Kapoulas Mech. Eng, Supervisor or asphaltic concrete production of Attiki Odos Mrs P. Tadoglou and Mr G. Voulgaris Chem. Eng, HELLENIC PETROLEUM S.A Mr. Lilis Mech. Eng, Metso Minerals SA Mr K. Priovolos Priovolos and Sons Ltd