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Concept of a Simulation Model for Assessing the Sustainable Development of Urban Transport
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ScienceDirect ScienceDirect
Transportation Research Procedia 00 (2018) 000–000 Available online at www.sciencedirect.com Transportation Research Procedia 00 (2018) 000–000
ScienceDirect
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Transportation Research Procedia 39 (2019) 502–513 www.elsevier.com/locate/procedia
Green Cities 2018 Green Cities 2018
Concept of a Simulation Model for Assessing the Sustainable Concept of a Simulation Model for Assessing the Sustainable Development of Urban Transport Development of Urban Transporta a a
Roma Strulak-Wójcikiewicza, Justyna Lemkea* Roma Strulak-Wójcikiewicz , Justyna Lemke *
Maritime University of Szczecin, Faculty of Economics and Transport Engineering, 11 H. Pobożnego Str, 70-507 Szczecin, Poland Maritime University of Szczecin, Faculty of Economics and Transport Engineering, 11 H. Pobożnego Str, 70-507 Szczecin, Poland
a
Abstract Abstract The article presents a concept of a simulation model for evaluation and assessment of the sustainable development of urban transport the social, economic environmental Urban is here understood as development combination of urban The articlein presents a concept of and a simulation modeldimensions. for evaluation andtransport assessment of the sustainable freight transport, passenger transport individual transport. The Urban concepttransport is illustrated by understood a set of environmental indicators for transport in the social, economic andand environmental dimensions. is here as combination of urban sustainable development oftransport urban transport. A system of sustainable development of by urban has been indicators defined. The freight transport, passenger and individual transport. The concept is illustrated a settransport of environmental for simulation model has beenofdeveloped as a consequence system dynamics that allowed indicators sustainable development urban transport. A system of of the sustainable development of urbanintegration transport of hasnumerous been defined. The of the sustainable development of urban transport (including the qualitative quantitative ones) and their simultaneous simulation model has been developed as a consequence of the system dynamics and that allowed integration of numerous indicators estimation with a dynamic approach. Furthermore, the(including concept present in the article provides aones) possibility to generate results of the sustainable development of urban transport the qualitative andalso quantitative and their simultaneous in a form of integrated sustainable They express thearticle degree ofprovides a given aphenomenon three different estimation with a dynamic approach.development Furthermore,indicators. the concept present in the also possibility toingenerate results dimensions, information on the complex phenomenon description in a very manner. in a form ofpresenting integrated the sustainable development indicators. They express the degree of aclear given phenomenon in three different dimensions, presenting the information on the complex phenomenon description in a very clear manner. © 2018 The Authors. Published by Elsevier B.V. © 2019 The Authors. Published by Elsevier B.V. This is an open accessPublished article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) © 2018 The Authors. by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection under responsibility of of Greener Cities This is an and openpeer-review access article under the CC BY-NC-ND licensecommittee (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the the scientific scientific committee of Green Green Logistics Logistics for for Greener Cities 2018. 2018. Selection and peer-review under responsibility of the scientific committee of Green Logistics for Greener Cities 2018. Keywords: sustainable development of urban transport, system dynamics, simulation model Keywords: sustainable development of urban transport, system dynamics, simulation model
1. Introduction 1. Introduction City is a key area of human activity. Cities exist to gather people, goods and activities within a restricted area. City is a keyeconomic area of human activity. Cities exist to gather people, goods and activities restricted area. This facilitates and social activity by reducing the time for exchange of goods andwithin ideas. aPorta and Latora This economic and social activity reducing exchange of goods and (Porta ideas. & Porta and Latora put itfacilitates directly: “Centralization is a key factorby that shapes the bothtime the for urban space and lifestyle" Latora, 2007). put it directly: is a key factor that shapes thethe urban space and lifestyle" (Porta Latora, More than half “Centralization of the Earth’s population has lived in citiesboth since beginning of 21st century. Since&1900, the2007). share More thanpopulation half of theincreased Earth’s population the49% beginning of (Browne, 21st century. Since 1900, the share of urban from 13%has to lived 29% in in cities 1950 since and to in 2005 Allen, Nemoto, Patier & of urban population increased from 13% to 29% in 1950 and to 49% in 2005 (Browne, Allen, Nemoto, Patier & * Tel.: +48-91-48-09-617 address: [email protected] * E-mail Tel.: +48-91-48-09-617 E-mail address: [email protected] 2352-1465 © 2018 The Authors. Published by Elsevier B.V. This is an open access under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) 2352-1465 © 2018 Thearticle Authors. Published by Elsevier B.V. Selection under responsibility of the scientific of Green Logistics for Greener Cities 2018. This is an and openpeer-review access article under the CC BY-NC-ND licensecommittee (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee of Green Logistics for Greener Cities 2018. 2352-1465 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee of Green Logistics for Greener Cities 2018. 10.1016/j.trpro.2019.06.052
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Visser, 2012). According to EU estimates, 80% of the population will live in European cities by 2020 (Quak, Lindholm, Tavasszy & Browne, 2016). This indicator has already reached 74% in 27 EU member states, while e.g. in the Netherlands or England the city dwellers are about 90% of the population. Today, cities occupy 2% of the Earth’s area, but they consume 75% of its resources (Kronenberg & Bergier, 2010). The city is a place of work, study, residence, leisure, shopping and the use of cultural goods. It is a place where numerous life needs of its inhabitants and visitors can be met, providing them with adequate conditions. Among these needs, the requirement for smooth movement and free access to various types of goods and services are of particular importance. The history of transport development is strictly related to development of cities. Transport is a physical thread that connects spatially distributed resources, human clusters, and different functional areas of a city - workplaces, trade, manufacturing, leisure, recreation, culture, etc. (Fertsch, 2008). It fulfills the individual and collective transport needs of population, and as a result of physical transfer of persons and freight (regarding manufacturing, service and commercial operations carried out within cities) it activates social and economic life at a specific time and place. Efficient transport is an element that provides the basis for the functioning of cities. It should be mentioned that in the city coexist public transport and urban freight transport systems. Also about the life quality in a city and its competitiveness towards other cities decides provision of efficient transport system for both people and freight. On the other hand, however, the noticeable increase in transport needs contributes to a number of difficulties, such as congestion, air quality, noise, CO2 emissions or accidents. The cities must develop and implement some cohesive and ambitious Sustainable Urban Mobility Plans (SUMP) to address these challenges. The requirements of sustainable development make it necessary to identify the links between social, economic and environmental relations. The main premise of the sustainable urban mobility concept is the strive for simultaneous consideration of human impact on the environment, social cohesion and economic growth - both now and in the future. This is related to the need to use limited resources, an attempt to improve the natural environment condition, to increase the economic competitiveness and social cohesion of cities. Hence, urban mobility is aimed at optimizing the use of transport means for urban journeys and creating co-modality between public and private transport for those journeys. The sustainable mobility plans pose one of the most effective tools for meeting the society’s needs for free movement, communication or business operations. A significant element in identification of the current situation and evaluation of the mobility solutions under implementation, is to use different indicators: both measurable (quantity) and non-measurable (quality), which are an attempt to measure and evaluate the sustainable urban transport in three dimensions: environmental, social and economic. Indicative measurement of the sustainability characteristics of urban transport is a major challenge. In the literature of the subject and numerous strategic documents of international and national organizations there is an extremely diverse approach to this issue, both in terms of the diversity of selected indicators and the methodology adopted for their measurement. These indicators relate to various stages and levels of analysis, from planning through behavior to the identification of internal and external impacts. A particular challenge in assessing sustainable transport is the dynamic nature of the different issues and the feedback between them. Therefore, the analyzed system becomes especially complex, and as such it forces adoption of adequate research techniques. Moreover, it is important for efficient management that the transportation system be based on holistic approach (Iwan & al., 2013). Hence, a proper tool for examination of sustainable development of urban transport seems to be the simulation model developed according to the Forester’s System Dynamic SD. Adoption of SD models allows integration of numerous sustainable urban transport indicators (including both the qualitative and quantitative ones) and their simultaneous estimation within a dynamic approach. In addition, it provides an opportunity to generate integrated indicators for the sustainable development of urban transport. They express the degree of a given phenomenon in three different dimensions, presenting the information on the complex phenomenon description in a very clear manner. Therefore, such a model makes it possible to provide comprehensive information on all the expected effects in dynamic and spatial terms and to reflect the secondary effects resulting from the internal dynamics of the examined system (Łatuszyńska & Strulak-Wójcikiewicz, 2013). The proposed approach complies with current trends in transport research, where simultaneous consideration of interconnected effects of transport development in the dynamic approach is recommended (Kuchenbecker & Rothengatter, 1999), (Yevdokimov, 2002), (Schade & Rothengatter, 2004).
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2. System for sustainable development of urban transport According to the systems theory, a system is a set of elements that remain in mutual interactions with each other and with the surroundings (Forrester, 1968), (Richardson, 1991), (Kuchenbecker & Rothengatter, 1999), (Yevdokimov, 2002). The system is a certain whole separated from the environment (e.g. urban environment) as a description in the form of a set of elements (subsystems) and a set of relations between these elements, as well as in relation to the environment. Separation of the system from its environment is intended to study the relations occurring within the system, the behavior of the system as a whole and the impact of the system on the environment. Therefore, it is important to distinguish a structure and its possible modifications for each system. It should be noted that the literature (Litman, 2011) (Schade & Rothengatter, 1999) emphasizes the close relationship between the transport system and economic, social and environmental systems (see fig. 1). These systems influence each other and interact. On the one hand, there are the "expectations" placed by the economic, social and ecological systems on the transport system (tasks resulting from needs and resources). On the other hand, the transport system exerts certain impact on the functioning of these systems with particular effects (Łatuszyńska, 2004). The above-mentioned interconnections between the transport system and the economic, social and ecological systems are reflected in the concept of the sustainable development concept (see more: (Borys, 2009), (Grzelawski, 2010). Most of the sustainable development current definitions cover three main categories of issues related to sustainability and sustainable development: economic, social and environmental (Borys, 2005), (Litman, 2008). The term ‘sustainable development’ means such development of careers that fulfills today’s needs without exposing the future generations to danger. Speaking more broadly, it is "a process of change where the use of resources, the direction of investment, the orientation of technological development and institutional changes are harmonized and increase both the current and future potential to meet human needs and aspirations" (Short, 1992).
Fig. 1. Three spheres of sustainability with inter-system connections Source: own study on the basis of: (Litman, 2011), (Schade & Rothengatter, 1999)
In the subjective perspective, the urbanized areas became the subject of the European transport policy quite late. By adopting the Green Paper "Towards a new culture for urban mobility" (COM(2007)55) in 2007, the European
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Commission launched a new phase of discussion which culminated in the publication of the "Action Plan on Urban Mobility" in 2009. The Green Paper drew attention to the fact that although urban mobility is of a local character, the effects of no actions within this field may have a European or even global dimension (Wołek & Wyszomirski, 2013). The notions of transport in cities have been highlighted in the White Book “Roadmap to a single European transport area - Towards competitive and resource-efficient transport system” (COM(2011)144), which postulates the necessity to integrate, among others, spatial planning, pricing systems, efficient public transport services and infrastructure for non-motorized means of transport within the urban mobility plans. The Urban Mobility Package (COM (2013)913 from the end of 2013 is a lesson from the White Paper 2011 . The Commission indicates the sustainable urban mobility plans as a horizontal priority, and they should be interdisciplinary, meaning they need to cover the issues of transport, land use and environmental protection, economic and social growth, health and road traffic safety (COM(2013)913). The sustainable urban mobility concept also considers the complexity of urban transport and strong links between the remaining systems and the transport. In view of the above considerations regarding the specificity of sustainable development, it has been assumed that the sustainable urban transport can be presented in a form of a system as a distinguished fragment of the urban reality. The concept of sustainable urban transport system is presented in fig. 2.
Fig. 2. Direction of sustainable development of urban transport Source: own study based on: (Newman & al., 1996)
The Extended Urban Metabolism Model (EUMM) developed by Newman et al. (1996) for State of the Environment reporting in Australia (Australia, 1998) interpret cities as dynamic urban system (population dynamics, economy, industry, infrastructure, transport, institution, linkages ) which require inputs of key resources (Land, water, Energy, Population, Finance) which are drawn into the urban processes and transform them into desirable livability outputs or Services (Employment, Income, Health, Education, Housing, Accessibility to services, Community life) and waste (Solid waste, Sewage, Air pollutants, Noise). The desirable change for the system is improvement of livability and reduction of waste. EUMM is closely aligned with the paradigm of sustainable development where future orientation, sustainability goals and targets and linkages among different dimensions are made explicit (Newton, 2001). While considering the concept for sustainable urban transport and the strict linkage of the transport system and the economic, social and ecological systems, the sustainable urban transport system should strive for reduction in negative impact on the surroundings (reduced undesired output). It should develop towards improvement in economic efficiency, social welfare and care of the environment to the level acceptable by the society (increased desired outputs) (see: fig.3).
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Fig. 3. Dimensions and direction of sustainable development of urban transport Source: own study adapted from (Newman & al., 1996)
Sustainable (in economic, social and environmental terms) urban transport system should take into account all forms of transport, prioritizing those most traditional, which at the same time generate the lowest external costs pedestrian traffic, cycling and public transport. Harmoniously developing urban transport should not be tempted to reduce the public transport for the sake of temporary savings, but it should rather optimize its use by infrastructural, organizational and marketing operations. Decisions made by the city on the urban transport system should be based on full awareness of their consequences and a cohesive strategy for growth, adopting the synergy effect, and not on temporary needs (Kronenberg & Bergier, 2010). 3. Indicators of the system for sustainable development of urban transport Management of a large and complex system like the urban transport involves great responsibility of the local authorities towards its users, and numerous social, economic and ecological challenges that emerge in the face of many processes and phenomena that take place within its area. The sustainable urban transport system is open and dynamic. This means that implementation of the mentioned objective requires constant monitoring and response to the changes that occur in the surroundings. Thus, there is a need for access to comprehensive and reliable information, including the data on indicators. There are plenty of classifications and typologies for the transport sustainable development indicators including the urban transport (urban mobility) available in the literature (see: Sdoukopoulos & Pitsiava-Latinopoulouwit, 2017, Nathan & Reddy, 2011, Litman, 2011, Jeon & Amekudzi 2005, Richardson, 2005, (OECD, 2002). Between 1996 and 2015, there were some 70 initiatives aimed at indicator-based assessment of the transport system (in global, national, regional or urban terms) or sustainable development, where transport was identified as a major component. They covered all dimensions of sustainable development (i.e. environmental, economic and social) or focused only on the environmental perspective. The indicator-based assessment of the urban transport sustainable development was carried out among others in the papers by (Gudmundsson, 2004, Rand Europe & al., 2004, Rodrigues da Silva, Costa & Ramos, 2010, Miranda & Rodrigues da Silva, 2012, A.D. Little, 2014, WBCSD, 2015, Arcadis, 2017, Cheba & Saniuk 2016). It should be noted that the cited authors chose the indicators for the sustainable transport (including urban transport) research freely (Black & al., 2002, Jeon & Amekudzi, 2005). It must however be stressed that many of the approaches to sustainable transport (including urban transport) assessment fail to highlight all three
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sustainability dimensions (economic, social and ecological), or while distinguishing particular indicators, fail to divide them into those three dimensions. Although other assessments divide the indicators into three dimensions mentioned above, there is no uniformity in the allocation of indicators to each dimension (Jeon & Amekudzi, 2005). When it comes to the spatial level of application of the sustainable transport indicators, there also is a high differentiation starting from the EU, through the national and regional, and ending at the urban level. Furthermore, each scientist adopts different methods of weighing and standardizing transport sustainability indicators. Similarly, as in the case of the number of indicators adopted for assessment, which varies from 8 to more than 100 in different approaches. A high level of variability in the approach to development of indicators reflects in poor correlation of new (other) and old indicators, leading to barriers regarding their comparability. This also refers to the applicability of indicators, as they sometimes require the collection of a large amount of data, which is expensive and can lead to difficulties in their application under different economic conditions. Additional difficulty is also the fact that some indicators are based on quantitative and others on qualitative data (Litman, 2013). Despite the barriers for development and application of the urban transport sustainable development indicators, all of them support the urban mobility assessment and are of great information value. Numerous initiatives on the urban transport sustainable development are reflected in practice, hence their presentation is interesting from the cognitive and implementation perspective. The data collected from those indicators may serve as good examples for other cities. It is not always necessary to use all the indicators presented in the above-mentioned initiatives to assess the sustainable development of urban transport (it results from the specificity of a given city and its transport system). Moreover, new indicators - more adequate for a given city - can be developed on the basis of the existing ones. Only exemplary indicators in the environmental dimension have been selected to present the concept of a systemically dynamic assessment of sustainable urban transport. To evaluate the sustainable transport, it is important to determine the impact of urban transport on particular elements of the environment. The sustainable transport assessment indicators that are most commonly used in the environmental dimension are presented in Table 1. Table 1. Comparison of environmental indicators from five sustainability frameworks Source (Canete-Medina, 2007). Indicator
Fuel Consumption CO2 Emissions Conventional Pollutants Emissions
SUMA (Rand & al., 2004)
Litman (Litman, 2009)
TERM (TERM, 2001)
X
X
X
X
X
Less is better
X
X
X
X
X
Less is better
X
X
X
X
X
Less is better
X
X
X
X
More is better
X
X
X
X
X
Less is better
X
X
X
X
X
Less is better
X
X
X
X
X
Less is better
X
X
X
X
X
More is better
X
X
X
Less is better
Air Quality Noise Pollution Water Pollution Land Take Preservation of Habitat Resource Consumption
STPI (Gilbert, Irwin, Hollingworth & Blais, 2002)
WBCSD (WBDSC, 2001)
Direction
While Land Take is determined according to the formula (1):
Tm ( wk ,m,l w p ,m,l ) Lm,l l
where:
(1)
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Tm wk,m,l wp,m,l Lm,l
7
- total area of land intake for the sake of transport infrastructure construction or modernisation for the means of transport m; - width of the edge l for the means of transport m after the investment has been completed; - initial width of the edge l for the means of transport m; - total length of the edge l for the means of transport m (Räsänen & al., 1999).
Air quality is determinant of volume of VOC, SO2, NO2, CO emissions: E p ,m k l ,m e p ,m l
(2)
where: - total emission of the type p pollutant [tonnes /year], Ep,m k l ,m - traffic congestion on the edge l for the means of transport m; - emission rate of the type p pollutant for the means of transport m (Hickman, 1999). ep,m Noise pollution means changes in the noise scale on the examined area: km2 below 55dB (A) Ll ,m log 10 (vm ) 10 log 10 (ql ,m )
where: Ll,m ql,m vm ,
(3)
- level of noise emitted along the edge l for the means of transport m in dB(A); - traffic flow on the edge l for the means of transport m; - mean speed of the means of transport m; - function parameters for the means of transport m (Müller-Wenk,1999).
Furthermore, also the number of accidents is also evaluated in the assessment of the sustainable urban transport development.
N p , m r p ,l , m k l , m g m l
(4)
where: - expected number of the type p accidents for the means of transport m, Npm - odds ratio of the type p accident on the edge l for the means of transport m; rp,l,m - traffic congestion on the edge l for the means of transport m; kl,m - mean load capacity of the means of transport m (Heich, 2000). gm It should be stressed that the use of a specific set of indicators in a given city requires a great deal of cooperation between research centres and local authorities. Especially when it comes to availability of the source data. 4. Concept of the simulation model for assessment of the urban transport sustainable development Taking the above into account, a causal model of the sustainable urban transport system development in relation to the environmental dimension has been developed (fig. 4).
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TRANSPORT INFRASTRUCTURE descriptive parameters of the infrastructure
transport traffic
impact on cultural goods
traffic safety
types of vehicle emission of pollutants health risk
occupation of land for transport infrastructure impact on the landscape
noise emission
impact on surface waters
impact on soil impact on lively nature
Fig. 4. A diagram of relationships among various elements in the environmental dimensions present in the urban transport Source: own study
Only this fragment shows that the urban transport sustainable development system is of a highly complex nature with numerous interconnections. Furthermore, the system is open, dynamic, and its long-term changes prove its continuous character. Hence, the choice of the Forrester’s system dynamics for assessment of the urban transport sustainable development seems adequate. The general structure of the proposed simulation model for assessment of the sustainable urban transport is composed of three basic sub-models: • • •
the environmental dimension sub-model, the social dimension sub-model, the economic dimension sub-model.
The environmental dimension sub-model aims to generate information on the environmental sustainability of urban transport (fig. 5). To determine indicators for the urban transport sustainable development in the environmental context, the environmental sub-model should be fed with such data as traffic volume, average vehicle speed, volume of transport, descriptive parameters of the transport network, etc. For determination of traffic streams in Szczecin, to consider among others reloading in ports and at railway stations, transports from and to nearby manufacturing, service facilities or tourist flows.
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emission of pollutant of type p at the time of day
Module of concentration of the total suspended solids
emission of pollutant of type p on the edge l for a type of vehicle m at the time of day
Module of traffic volumes
Module of noise emissions
index of emission for a type of vehicle m
equivalent level of noise emitted by vehicle traffic on the edge l
Module of pollutant emissions
real speed of the vehicle type m on the edge l
parameter alfa
ray of exposure to noise levels higher than normal on the edge l
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Green Cities 2018 Green Cities 2018
Concept of a Simulation Model for Assessing the Sustainable Concept of a Simulation Model for Assessing the Sustainable Development of Urban Transport Development of Urban Transporta a a
Roma Strulak-Wójcikiewicza, Justyna Lemkea* Roma Strulak-Wójcikiewicz , Justyna Lemke *
Maritime University of Szczecin, Faculty of Economics and Transport Engineering, 11 H. Pobożnego Str, 70-507 Szczecin, Poland Maritime University of Szczecin, Faculty of Economics and Transport Engineering, 11 H. Pobożnego Str, 70-507 Szczecin, Poland
a
Abstract Abstract The article presents a concept of a simulation model for evaluation and assessment of the sustainable development of urban transport the social, economic environmental Urban is here understood as development combination of urban The articlein presents a concept of and a simulation modeldimensions. for evaluation andtransport assessment of the sustainable freight transport, passenger transport individual transport. The Urban concepttransport is illustrated by understood a set of environmental indicators for transport in the social, economic andand environmental dimensions. is here as combination of urban sustainable development oftransport urban transport. A system of sustainable development of by urban has been indicators defined. The freight transport, passenger and individual transport. The concept is illustrated a settransport of environmental for simulation model has beenofdeveloped as a consequence system dynamics that allowed indicators sustainable development urban transport. A system of of the sustainable development of urbanintegration transport of hasnumerous been defined. The of the sustainable development of urban transport (including the qualitative quantitative ones) and their simultaneous simulation model has been developed as a consequence of the system dynamics and that allowed integration of numerous indicators estimation with a dynamic approach. Furthermore, the(including concept present in the article provides aones) possibility to generate results of the sustainable development of urban transport the qualitative andalso quantitative and their simultaneous in a form of integrated sustainable They express thearticle degree ofprovides a given aphenomenon three different estimation with a dynamic approach.development Furthermore,indicators. the concept present in the also possibility toingenerate results dimensions, information on the complex phenomenon description in a very manner. in a form ofpresenting integrated the sustainable development indicators. They express the degree of aclear given phenomenon in three different dimensions, presenting the information on the complex phenomenon description in a very clear manner. © 2018 The Authors. Published by Elsevier B.V. © 2019 The Authors. Published by Elsevier B.V. This is an open accessPublished article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) © 2018 The Authors. by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection under responsibility of of Greener Cities This is an and openpeer-review access article under the CC BY-NC-ND licensecommittee (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the the scientific scientific committee of Green Green Logistics Logistics for for Greener Cities 2018. 2018. Selection and peer-review under responsibility of the scientific committee of Green Logistics for Greener Cities 2018. Keywords: sustainable development of urban transport, system dynamics, simulation model Keywords: sustainable development of urban transport, system dynamics, simulation model
1. Introduction 1. Introduction City is a key area of human activity. Cities exist to gather people, goods and activities within a restricted area. City is a keyeconomic area of human activity. Cities exist to gather people, goods and activities restricted area. This facilitates and social activity by reducing the time for exchange of goods andwithin ideas. aPorta and Latora This economic and social activity reducing exchange of goods and (Porta ideas. & Porta and Latora put itfacilitates directly: “Centralization is a key factorby that shapes the bothtime the for urban space and lifestyle" Latora, 2007). put it directly: is a key factor that shapes thethe urban space and lifestyle" (Porta Latora, More than half “Centralization of the Earth’s population has lived in citiesboth since beginning of 21st century. Since&1900, the2007). share More thanpopulation half of theincreased Earth’s population the49% beginning of (Browne, 21st century. Since 1900, the share of urban from 13%has to lived 29% in in cities 1950 since and to in 2005 Allen, Nemoto, Patier & of urban population increased from 13% to 29% in 1950 and to 49% in 2005 (Browne, Allen, Nemoto, Patier & * Tel.: +48-91-48-09-617 address: [email protected] * E-mail Tel.: +48-91-48-09-617 E-mail address: [email protected] 2352-1465 © 2018 The Authors. Published by Elsevier B.V. This is an open access under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) 2352-1465 © 2018 Thearticle Authors. Published by Elsevier B.V. Selection under responsibility of the scientific of Green Logistics for Greener Cities 2018. This is an and openpeer-review access article under the CC BY-NC-ND licensecommittee (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee of Green Logistics for Greener Cities 2018. 2352-1465 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee of Green Logistics for Greener Cities 2018. 10.1016/j.trpro.2019.06.052
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Visser, 2012). According to EU estimates, 80% of the population will live in European cities by 2020 (Quak, Lindholm, Tavasszy & Browne, 2016). This indicator has already reached 74% in 27 EU member states, while e.g. in the Netherlands or England the city dwellers are about 90% of the population. Today, cities occupy 2% of the Earth’s area, but they consume 75% of its resources (Kronenberg & Bergier, 2010). The city is a place of work, study, residence, leisure, shopping and the use of cultural goods. It is a place where numerous life needs of its inhabitants and visitors can be met, providing them with adequate conditions. Among these needs, the requirement for smooth movement and free access to various types of goods and services are of particular importance. The history of transport development is strictly related to development of cities. Transport is a physical thread that connects spatially distributed resources, human clusters, and different functional areas of a city - workplaces, trade, manufacturing, leisure, recreation, culture, etc. (Fertsch, 2008). It fulfills the individual and collective transport needs of population, and as a result of physical transfer of persons and freight (regarding manufacturing, service and commercial operations carried out within cities) it activates social and economic life at a specific time and place. Efficient transport is an element that provides the basis for the functioning of cities. It should be mentioned that in the city coexist public transport and urban freight transport systems. Also about the life quality in a city and its competitiveness towards other cities decides provision of efficient transport system for both people and freight. On the other hand, however, the noticeable increase in transport needs contributes to a number of difficulties, such as congestion, air quality, noise, CO2 emissions or accidents. The cities must develop and implement some cohesive and ambitious Sustainable Urban Mobility Plans (SUMP) to address these challenges. The requirements of sustainable development make it necessary to identify the links between social, economic and environmental relations. The main premise of the sustainable urban mobility concept is the strive for simultaneous consideration of human impact on the environment, social cohesion and economic growth - both now and in the future. This is related to the need to use limited resources, an attempt to improve the natural environment condition, to increase the economic competitiveness and social cohesion of cities. Hence, urban mobility is aimed at optimizing the use of transport means for urban journeys and creating co-modality between public and private transport for those journeys. The sustainable mobility plans pose one of the most effective tools for meeting the society’s needs for free movement, communication or business operations. A significant element in identification of the current situation and evaluation of the mobility solutions under implementation, is to use different indicators: both measurable (quantity) and non-measurable (quality), which are an attempt to measure and evaluate the sustainable urban transport in three dimensions: environmental, social and economic. Indicative measurement of the sustainability characteristics of urban transport is a major challenge. In the literature of the subject and numerous strategic documents of international and national organizations there is an extremely diverse approach to this issue, both in terms of the diversity of selected indicators and the methodology adopted for their measurement. These indicators relate to various stages and levels of analysis, from planning through behavior to the identification of internal and external impacts. A particular challenge in assessing sustainable transport is the dynamic nature of the different issues and the feedback between them. Therefore, the analyzed system becomes especially complex, and as such it forces adoption of adequate research techniques. Moreover, it is important for efficient management that the transportation system be based on holistic approach (Iwan & al., 2013). Hence, a proper tool for examination of sustainable development of urban transport seems to be the simulation model developed according to the Forester’s System Dynamic SD. Adoption of SD models allows integration of numerous sustainable urban transport indicators (including both the qualitative and quantitative ones) and their simultaneous estimation within a dynamic approach. In addition, it provides an opportunity to generate integrated indicators for the sustainable development of urban transport. They express the degree of a given phenomenon in three different dimensions, presenting the information on the complex phenomenon description in a very clear manner. Therefore, such a model makes it possible to provide comprehensive information on all the expected effects in dynamic and spatial terms and to reflect the secondary effects resulting from the internal dynamics of the examined system (Łatuszyńska & Strulak-Wójcikiewicz, 2013). The proposed approach complies with current trends in transport research, where simultaneous consideration of interconnected effects of transport development in the dynamic approach is recommended (Kuchenbecker & Rothengatter, 1999), (Yevdokimov, 2002), (Schade & Rothengatter, 2004).
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2. System for sustainable development of urban transport According to the systems theory, a system is a set of elements that remain in mutual interactions with each other and with the surroundings (Forrester, 1968), (Richardson, 1991), (Kuchenbecker & Rothengatter, 1999), (Yevdokimov, 2002). The system is a certain whole separated from the environment (e.g. urban environment) as a description in the form of a set of elements (subsystems) and a set of relations between these elements, as well as in relation to the environment. Separation of the system from its environment is intended to study the relations occurring within the system, the behavior of the system as a whole and the impact of the system on the environment. Therefore, it is important to distinguish a structure and its possible modifications for each system. It should be noted that the literature (Litman, 2011) (Schade & Rothengatter, 1999) emphasizes the close relationship between the transport system and economic, social and environmental systems (see fig. 1). These systems influence each other and interact. On the one hand, there are the "expectations" placed by the economic, social and ecological systems on the transport system (tasks resulting from needs and resources). On the other hand, the transport system exerts certain impact on the functioning of these systems with particular effects (Łatuszyńska, 2004). The above-mentioned interconnections between the transport system and the economic, social and ecological systems are reflected in the concept of the sustainable development concept (see more: (Borys, 2009), (Grzelawski, 2010). Most of the sustainable development current definitions cover three main categories of issues related to sustainability and sustainable development: economic, social and environmental (Borys, 2005), (Litman, 2008). The term ‘sustainable development’ means such development of careers that fulfills today’s needs without exposing the future generations to danger. Speaking more broadly, it is "a process of change where the use of resources, the direction of investment, the orientation of technological development and institutional changes are harmonized and increase both the current and future potential to meet human needs and aspirations" (Short, 1992).
Fig. 1. Three spheres of sustainability with inter-system connections Source: own study on the basis of: (Litman, 2011), (Schade & Rothengatter, 1999)
In the subjective perspective, the urbanized areas became the subject of the European transport policy quite late. By adopting the Green Paper "Towards a new culture for urban mobility" (COM(2007)55) in 2007, the European
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Commission launched a new phase of discussion which culminated in the publication of the "Action Plan on Urban Mobility" in 2009. The Green Paper drew attention to the fact that although urban mobility is of a local character, the effects of no actions within this field may have a European or even global dimension (Wołek & Wyszomirski, 2013). The notions of transport in cities have been highlighted in the White Book “Roadmap to a single European transport area - Towards competitive and resource-efficient transport system” (COM(2011)144), which postulates the necessity to integrate, among others, spatial planning, pricing systems, efficient public transport services and infrastructure for non-motorized means of transport within the urban mobility plans. The Urban Mobility Package (COM (2013)913 from the end of 2013 is a lesson from the White Paper 2011 . The Commission indicates the sustainable urban mobility plans as a horizontal priority, and they should be interdisciplinary, meaning they need to cover the issues of transport, land use and environmental protection, economic and social growth, health and road traffic safety (COM(2013)913). The sustainable urban mobility concept also considers the complexity of urban transport and strong links between the remaining systems and the transport. In view of the above considerations regarding the specificity of sustainable development, it has been assumed that the sustainable urban transport can be presented in a form of a system as a distinguished fragment of the urban reality. The concept of sustainable urban transport system is presented in fig. 2.
Fig. 2. Direction of sustainable development of urban transport Source: own study based on: (Newman & al., 1996)
The Extended Urban Metabolism Model (EUMM) developed by Newman et al. (1996) for State of the Environment reporting in Australia (Australia, 1998) interpret cities as dynamic urban system (population dynamics, economy, industry, infrastructure, transport, institution, linkages ) which require inputs of key resources (Land, water, Energy, Population, Finance) which are drawn into the urban processes and transform them into desirable livability outputs or Services (Employment, Income, Health, Education, Housing, Accessibility to services, Community life) and waste (Solid waste, Sewage, Air pollutants, Noise). The desirable change for the system is improvement of livability and reduction of waste. EUMM is closely aligned with the paradigm of sustainable development where future orientation, sustainability goals and targets and linkages among different dimensions are made explicit (Newton, 2001). While considering the concept for sustainable urban transport and the strict linkage of the transport system and the economic, social and ecological systems, the sustainable urban transport system should strive for reduction in negative impact on the surroundings (reduced undesired output). It should develop towards improvement in economic efficiency, social welfare and care of the environment to the level acceptable by the society (increased desired outputs) (see: fig.3).
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Fig. 3. Dimensions and direction of sustainable development of urban transport Source: own study adapted from (Newman & al., 1996)
Sustainable (in economic, social and environmental terms) urban transport system should take into account all forms of transport, prioritizing those most traditional, which at the same time generate the lowest external costs pedestrian traffic, cycling and public transport. Harmoniously developing urban transport should not be tempted to reduce the public transport for the sake of temporary savings, but it should rather optimize its use by infrastructural, organizational and marketing operations. Decisions made by the city on the urban transport system should be based on full awareness of their consequences and a cohesive strategy for growth, adopting the synergy effect, and not on temporary needs (Kronenberg & Bergier, 2010). 3. Indicators of the system for sustainable development of urban transport Management of a large and complex system like the urban transport involves great responsibility of the local authorities towards its users, and numerous social, economic and ecological challenges that emerge in the face of many processes and phenomena that take place within its area. The sustainable urban transport system is open and dynamic. This means that implementation of the mentioned objective requires constant monitoring and response to the changes that occur in the surroundings. Thus, there is a need for access to comprehensive and reliable information, including the data on indicators. There are plenty of classifications and typologies for the transport sustainable development indicators including the urban transport (urban mobility) available in the literature (see: Sdoukopoulos & Pitsiava-Latinopoulouwit, 2017, Nathan & Reddy, 2011, Litman, 2011, Jeon & Amekudzi 2005, Richardson, 2005, (OECD, 2002). Between 1996 and 2015, there were some 70 initiatives aimed at indicator-based assessment of the transport system (in global, national, regional or urban terms) or sustainable development, where transport was identified as a major component. They covered all dimensions of sustainable development (i.e. environmental, economic and social) or focused only on the environmental perspective. The indicator-based assessment of the urban transport sustainable development was carried out among others in the papers by (Gudmundsson, 2004, Rand Europe & al., 2004, Rodrigues da Silva, Costa & Ramos, 2010, Miranda & Rodrigues da Silva, 2012, A.D. Little, 2014, WBCSD, 2015, Arcadis, 2017, Cheba & Saniuk 2016). It should be noted that the cited authors chose the indicators for the sustainable transport (including urban transport) research freely (Black & al., 2002, Jeon & Amekudzi, 2005). It must however be stressed that many of the approaches to sustainable transport (including urban transport) assessment fail to highlight all three
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sustainability dimensions (economic, social and ecological), or while distinguishing particular indicators, fail to divide them into those three dimensions. Although other assessments divide the indicators into three dimensions mentioned above, there is no uniformity in the allocation of indicators to each dimension (Jeon & Amekudzi, 2005). When it comes to the spatial level of application of the sustainable transport indicators, there also is a high differentiation starting from the EU, through the national and regional, and ending at the urban level. Furthermore, each scientist adopts different methods of weighing and standardizing transport sustainability indicators. Similarly, as in the case of the number of indicators adopted for assessment, which varies from 8 to more than 100 in different approaches. A high level of variability in the approach to development of indicators reflects in poor correlation of new (other) and old indicators, leading to barriers regarding their comparability. This also refers to the applicability of indicators, as they sometimes require the collection of a large amount of data, which is expensive and can lead to difficulties in their application under different economic conditions. Additional difficulty is also the fact that some indicators are based on quantitative and others on qualitative data (Litman, 2013). Despite the barriers for development and application of the urban transport sustainable development indicators, all of them support the urban mobility assessment and are of great information value. Numerous initiatives on the urban transport sustainable development are reflected in practice, hence their presentation is interesting from the cognitive and implementation perspective. The data collected from those indicators may serve as good examples for other cities. It is not always necessary to use all the indicators presented in the above-mentioned initiatives to assess the sustainable development of urban transport (it results from the specificity of a given city and its transport system). Moreover, new indicators - more adequate for a given city - can be developed on the basis of the existing ones. Only exemplary indicators in the environmental dimension have been selected to present the concept of a systemically dynamic assessment of sustainable urban transport. To evaluate the sustainable transport, it is important to determine the impact of urban transport on particular elements of the environment. The sustainable transport assessment indicators that are most commonly used in the environmental dimension are presented in Table 1. Table 1. Comparison of environmental indicators from five sustainability frameworks Source (Canete-Medina, 2007). Indicator
Fuel Consumption CO2 Emissions Conventional Pollutants Emissions
SUMA (Rand & al., 2004)
Litman (Litman, 2009)
TERM (TERM, 2001)
X
X
X
X
X
Less is better
X
X
X
X
X
Less is better
X
X
X
X
X
Less is better
X
X
X
X
More is better
X
X
X
X
X
Less is better
X
X
X
X
X
Less is better
X
X
X
X
X
Less is better
X
X
X
X
X
More is better
X
X
X
Less is better
Air Quality Noise Pollution Water Pollution Land Take Preservation of Habitat Resource Consumption
STPI (Gilbert, Irwin, Hollingworth & Blais, 2002)
WBCSD (WBDSC, 2001)
Direction
While Land Take is determined according to the formula (1):
Tm ( wk ,m,l w p ,m,l ) Lm,l l
where:
(1)
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Tm wk,m,l wp,m,l Lm,l
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- total area of land intake for the sake of transport infrastructure construction or modernisation for the means of transport m; - width of the edge l for the means of transport m after the investment has been completed; - initial width of the edge l for the means of transport m; - total length of the edge l for the means of transport m (Räsänen & al., 1999).
Air quality is determinant of volume of VOC, SO2, NO2, CO emissions: E p ,m k l ,m e p ,m l
(2)
where: - total emission of the type p pollutant [tonnes /year], Ep,m k l ,m - traffic congestion on the edge l for the means of transport m; - emission rate of the type p pollutant for the means of transport m (Hickman, 1999). ep,m Noise pollution means changes in the noise scale on the examined area: km2 below 55dB (A) Ll ,m log 10 (vm ) 10 log 10 (ql ,m )
where: Ll,m ql,m vm ,
(3)
- level of noise emitted along the edge l for the means of transport m in dB(A); - traffic flow on the edge l for the means of transport m; - mean speed of the means of transport m; - function parameters for the means of transport m (Müller-Wenk,1999).
Furthermore, also the number of accidents is also evaluated in the assessment of the sustainable urban transport development.
N p , m r p ,l , m k l , m g m l
(4)
where: - expected number of the type p accidents for the means of transport m, Npm - odds ratio of the type p accident on the edge l for the means of transport m; rp,l,m - traffic congestion on the edge l for the means of transport m; kl,m - mean load capacity of the means of transport m (Heich, 2000). gm It should be stressed that the use of a specific set of indicators in a given city requires a great deal of cooperation between research centres and local authorities. Especially when it comes to availability of the source data. 4. Concept of the simulation model for assessment of the urban transport sustainable development Taking the above into account, a causal model of the sustainable urban transport system development in relation to the environmental dimension has been developed (fig. 4).
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TRANSPORT INFRASTRUCTURE descriptive parameters of the infrastructure
transport traffic
impact on cultural goods
traffic safety
types of vehicle emission of pollutants health risk
occupation of land for transport infrastructure impact on the landscape
noise emission
impact on surface waters
impact on soil impact on lively nature
Fig. 4. A diagram of relationships among various elements in the environmental dimensions present in the urban transport Source: own study
Only this fragment shows that the urban transport sustainable development system is of a highly complex nature with numerous interconnections. Furthermore, the system is open, dynamic, and its long-term changes prove its continuous character. Hence, the choice of the Forrester’s system dynamics for assessment of the urban transport sustainable development seems adequate. The general structure of the proposed simulation model for assessment of the sustainable urban transport is composed of three basic sub-models: • • •
the environmental dimension sub-model, the social dimension sub-model, the economic dimension sub-model.
The environmental dimension sub-model aims to generate information on the environmental sustainability of urban transport (fig. 5). To determine indicators for the urban transport sustainable development in the environmental context, the environmental sub-model should be fed with such data as traffic volume, average vehicle speed, volume of transport, descriptive parameters of the transport network, etc. For determination of traffic streams in Szczecin, to consider among others reloading in ports and at railway stations, transports from and to nearby manufacturing, service facilities or tourist flows.
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emission of pollutant of type p at the time of day
Module of concentration of the total suspended solids
emission of pollutant of type p on the edge l for a type of vehicle m at the time of day
Module of traffic volumes
Module of noise emissions
index of emission for a type of vehicle m
equivalent level of noise emitted by vehicle traffic on the edge l
Module of pollutant emissions
real speed of the vehicle type m on the edge l
parameter alfa
ray of exposure to noise levels higher than normal on the edge l