| 1. |
- Sundell, Jonas, 1984, et al.
(författare)
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Comprehensive risk assessment of groundwater drawdown induced subsidence
- 2019
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Ingår i: Stochastic Environmental Research and Risk Assessment. - : Springer Science and Business Media LLC. - 1436-3240 .- 1436-3259. ; 33:2, s. 427-449
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Tidskriftsartikel (refereegranskat)abstract
- © 2019, The Author(s). We present a method for risk assessment of groundwater drawdown induced land subsidence when planning for sub-surface infrastructure. Since groundwater drawdown and related subsidence can occur at large distances from the points of inflow, the large spatial extent often implies heterogeneous geological conditions that cannot be described in complete detail. This calls for estimation of uncertainties in all components of the cause-effect chain with probabilistic methods. In this study, we couple four probabilistic methods into a comprehensive model for economic risk quantification: a geostatistical soil-stratification model, an inverse calibrated groundwater model, an elasto-plastic subsidence model, and a model describing the resulting damages and costs on individual buildings and constructions. Groundwater head measurements, hydraulic tests, statistical analyses of stratification and soil properties and an inventory of buildings are inputs to the models. In the coupled method, different design alternatives for risk reduction measures are evaluated. Integration of probabilities and damage costs result in an economic risk estimate for each alternative. Compared with the risk for a reference alternative, the best prior alternative is identified as the alternative with the highest expected net benefit. The results include spatial probabilistic risk estimates for each alternative where areas with significant risk are distinguished from low-risk areas. The efficiency and usefulness of this modelling approach as a tool for communication to stakeholders, decision support for prioritization of risk reducing measures, and identification of the need for further investigations and monitoring are demonstrated with a case study of a planned railway tunnel in Varberg, Sweden.
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| 2. |
- Sundell, Jonas, 1984, et al.
(författare)
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Economic valuation of hydrogeological information when managing groundwater drawdown
- 2019
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Ingår i: Hydrogeology Journal. - : Springer Science and Business Media LLC. - 1431-2174 .- 1435-0157. ; 27:4, s. 1111-1130
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Tidskriftsartikel (refereegranskat)abstract
- © 2019, The Author(s). A procedure is presented for valuation of information analysis (VOIA) to determine the need for additional information when assessing the effect of several design alternatives to manage future disturbances in hydrogeological systems. When planning for groundwater extraction and drawdown in areas where risks—such as land subsidence, wells running dry and drainage of streams and wetlands—are present, the need for risk-reducing safety measures must be carefully evaluated and managed. The heterogeneity of the subsurface calls for an assessment of trade-offs between the benefits of additional information to reduce the risk of erroneous decisions and the cost of collecting this information. A method is suggested that combines existing procedures for inverse probabilistic groundwater modelling with a novel method for VOIA. The method results in (1) a prior analysis where uncertainties regarding the efficiency of safety measures are estimated, and (2) a pre-posterior analysis, where the benefits of expected uncertainty reduction deriving from additional information are compared with the costs for obtaining this information. In comparison with existing approaches for VOIA, the method can assess multiple design alternatives, use hydrogeological parameters as proxies for failure, and produce spatially distributed VOIA maps. The method is demonstrated for a case study of a planned tunnel in Stockholm, Sweden, where additional investigations produce a low number of benefits as a result of low failure rates for the studied alternatives and a cause-effect chain where the resulting failure probability is more dependent on interactions within the whole system rather than on specific features.
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| 3. |
- Dymitrow, Mirek, et al.
(författare)
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Crossing dichotomies and breaking mental patterns: Green business development when all else fails?
- 2017
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Ingår i: 8th International Scientific Conference “Rural Development 2017: Bioeconomy Challenges”, 23–24 November, 2017 Kaunas, Lithuania.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Obtaining sustainable and inclusive societal organization is not merely a simple matter of ‘doing it’ by subscribing to some winning formula. Given that conceptual frameworks always guide our thoughts, judgments and actions (Latour, 2013; Harvey, 1996; Dennett, 1993), the ways in which we relate to concepts chosen to serve as guiding forces for future development will eventually determine its outcome. As scholarly evidence continuously suggests the concepts ‘rural’ and ‘urban’ are increasingly recognized as artificial barriers for conducting sound and integrated development endeavors in a globalized reality of interconnectedness. In line with the Sustainable Development Goals, which aim to eradicate poverty, shield the planet and safeguard prosperity for all, commitment to universal access to healthy food year round has become an important agenda point. This, however, has been exacerbated by binary thinking and separate ways of doing policy. This paper aims to share experiences from a unique project launched in the northern parts of Gothenburg, Sweden’s second largest city. While the area offers ample resources and immense opportunities for areal economies, it at the same time remains one of Gothenburg’s most segregated, with high levels of unemployment, ill health and crime. The uniqueness of the project lies not only in its way of abridging the rural-urban divide, but also by consciously deferring from the debilitating rhetoric of previous ‘immigrant policies’, and instead focusing on agricultural productivity, small-scale food producers and sustainable food strategies. Such exhortations to bridge between philosophical and material polarities, however, have not come without conceptual and practical challenges, something this paper aims to subsume and open up to debate.
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| 4. |
- Adl-Zarrabi, Bijan, 1959, et al.
(författare)
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Safe and Sustainable Coastal Highway Route E39
- 2016
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Ingår i: Transportation Research Procedia. - : Elsevier BV. - 2352-1465 .- 2352-1457. ; 14, s. 3350-3359
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Konferensbidrag (refereegranskat)abstract
- The project “Coastal Highway Route E39” have a mandate to, investigate how infrastructure can exploit renewable energy to reduce environmental footprint. Three PhD projects were initiated on this subject at Chalmers University of Technology by Norwegian public road administration. Results in this paper conclude that (1) Life Cycle Assessment should have a geographical dimension with respect to assumptions and input data, (2) there are substantial potential to reduce the CO2 emissions from the E39, especially when considering an electrification, and (3) the harvested energy from hydronic pavement system can be enough for maintaining ice-free roads in Nordic countries.
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| 5. |
- Aygül, Mustafa, 1970, et al.
(författare)
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A comparative study of different fatigue failure assessments of welded bridge details
- 2013
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Ingår i: International Journal of Fatigue. - : Elsevier BV. - 0142-1123. ; 49:0, s. 62-72
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Tidskriftsartikel (refereegranskat)abstract
- Five different welded joints frequently used in steel bridges have been selected to investigate the accuracy and applicability of three fatigue assessment methods. The first method, also categorised as the global method, is the nominal stress method, while the more advanced methods are the hot spot and the effective notch stress methods. Solid element based finite element models for welded bridge details were created by following the modelling requirements of each fatigue assessment method. A statistical evaluation based on the results of the finite element analyses and the fatigue test data collected from the literature was performed to determine the mean and characteristic fatigue strength. In addition, the standard deviation for each data series was also determined to conclude how well each method describes the fatigue strength of each welded detail. A method with a lower standard deviation is regarded as more accurate. Moreover, the evaluated results from each method were compared with the recommended fatigue strength values in the Eurocode 3 (EN 1993-1-9:2005) and IIW codes. In the light of the test results in this study, it appears that the codes are in reasonable agreement with the test data, even though a few examples of the opposite occurred. The conclusion based on the revised results in this article indicates that the nominal stress method yields satisfactory results, despite its simplicity. When considering the effort involved in creating FE models for numerical analysis, it seems clear that the choice of the nominal method is fairly acceptable.
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| 6. |
- Blomfors, Martin, et al.
(författare)
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Reliability analysis of corroded reinforced concrete beam with regards to anchorage failure
- 2019
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Ingår i: Life-Cycle Analysis and Assessment in Civil Engineering. - : CRC Press/Balkema. - 9781138626331 - 9781351857574 ; , s. 337-344, s. 337-344
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Konferensbidrag (refereegranskat)abstract
- Reinforcement corrosion is a common problem in reinforced concrete infrastructure today, and it is expected to increase in the future. To simply replace the corroded structures with new ones requires large resources, both in financial and environmental terms. Therefore it is important that existing structures are used to their full potential, also after the onset of corrosion. This paper presents a reliability study of the anchorage capacity of a reinforced concrete beam including reinforcement corrosion. The sensitivity of the different input parameters is also studied. As expected, the results show that the reliability is reduced with corrosion; the magnitude depends to a large extent on the modelling uncertainty used for the bond model for corroded reinforcement. The sensitivity analysis shows an influence of corrosion also on the sensitivities of the input parameters, which is expected based on the properties of the underlying bond model. This paper demonstrates that probabilistic evaluations give valuable insight of the reliability, which can be used to prolong the service-life of existing infrastructure and save both money and the environment.
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| 7. |
- Thunberg, Micael, 1986-, et al.
(författare)
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Categorising on-site problems : A supply chain management perspective on construction projects
- 2017
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Ingår i: Construction Innovation. - : Emerald Group Publishing Limited. - 1471-4175 .- 1477-0857. ; 17:1, s. 90-111
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - This study aims to identify and categorise common on-site problems from a supply chain management (SCM) perspective and to trace the origin of these problems in the construction project process, the supply chain or in the intersection between these processes. This allows for identification of how on-site problems affect SCM in construction projects and how they can be mitigated. Design/methodology/approach - A literature review in combination with semi-structured interviews was used to identify on-site problems. This enabled triangulation and strengthened both construct validity and internal validity. Findings - On-site problems can be categorised in one of the four following categories: material flows, internal communication, external communication or complexity. The first category has its origin in the supply chain, the second in the construction project process, the third in the supply chain-construction process intersection on site and the fourth in the construction project as a whole. The findings conclude that on-site problems often originate from construction companies' lack of supply chain orientation. Research limitations/implications - It is suggested that supply chain planning (SCP) can facilitate on-site problem mitigation in construction project management. This extends the body of knowledge of SCP in construction project management and supports the development of effective on-site construction project management. Practical implications - The results show that SCP can aid construction project management in handling on-site problems earlier in the project process. Originality/value - The main value lies in extending the body of knowledge in construction project management research by applying an SCM perspective and by introducing SCP to support more effective construction project management.
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| 8. |
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| 9. |
- Ståhle, Alexander, et al.
(författare)
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Designguide för Smarta gator
- 2022
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Designguiden för smarta gator konkretiserar hur de fyra megatrenderna urbanisering, digitalisering, samhällsförändringar och miljöförändringar leder till nya krav och utformningsprinciper för framtidens gator. Guiden är tänkt att fungera som en inspiration och ett underlag för att förnya svensk gatupolicy på nationell, regional och kommunal nivå.Guiden innehåller utöver en inledning följande kapitel: en historisk tillbakablick (gatans utveckling), gatans användning, gatans delar, gatans design, designprocessen, guidens genomförande.
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| 10. |
- Estévez Mauriz, Laura, 1982
(författare)
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The urban form and the sound environment - Tools and approaches
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cities are always confronted with transition and adaptation. Awareness on urban environmental quality is leading the vision about the built environment’s resilience and sustainability, highlighting the importance of a multidisciplinary framework for urbanisation processes. One of the main concerns is the negative impact of outdoor noise due to road traffic, whereby controlling the sound environment through good quality spatial production is a priority. Europe and other parts of the world are experiencing a chronic traffic congestion problem. The environmental impact of this situation is overwhelming, where 90 % of the health impact due to noise exposure is estimated to be caused by road traffic noise. In this regard, noise maps are seen as a powerful tool in the development of new urban areas, where its noise level underestimation can endanger the wellbeing of citizens. At this rapid urbanisation, divided pronouncements on decision-making are devastating. The aim is to overcome negative aspects derived from a late intervention by including urban sound planning as an opportunity to the user’s experience and wellbeing, avoiding poor patches in the urban configuration and economical burden. The present work is committed to the development of tools for controlling, communicating and designing the sound environment on a level beyond today’s solutions, capable to be included at the early stages of the planning process. First, the study goes through the importance of the quiet side and the implementation of an engineering method as a powerful tool in the urban development, obtaining accurate results compared to measurements. In an attempt to study time variations of traffic within cities and its relevance regarding noise emission (normally overlooked in current noise mapping calculations), a microscopic road traffic modelling tool is developed in the second study, giving useful output for noise level predictions as function of time. The time-pattern analysis opens the possibility to test traffic configurations and explore a large variety of results in the form of descriptors as statistical indicators, calm periods and noise events, and outcomes as difference maps and contribution maps. The third study extends toward the evaluation of the effects of spatial heterogeneity (considered a key strategy to increase the liveability of spaces) on the environmental performance and resilience capacity of the transportation system through the study of noise pollution and its economic impact. The studies presented are using real case scenarios as a test-bed not only for implementation, but mainly for the development of tools.
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| 11. |
- Kickert, Conrad Christiaan, et al.
(författare)
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Surveying density, urban characteristics, and development capacity of station areas in the Delta Metropolis
- 2014
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Ingår i: Environment and Planning B: Planning and Design. - : SAGE Publications. - 2399-8083 .- 2399-8091 .- 0265-8135 .- 1472-3417. ; 41, s. 69-92
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Tidskriftsartikel (refereegranskat)abstract
- The combination of growing mobility needs and dwindling transportation budgets in the Dutch Delta Metropolis has raised the need for smarter use of existing public transport infrastructure. A significant portion of this smarter use may come from strengthening the ties between infrastructure improvements and transit-oriented development. To further this goal, the Delta Metropolis Association has developed SprintCity (SprintStad in Dutch), a serious game and planning support tool that engages stakeholders in transit-oriented development to explore interaction between transport and land use, as described in Bertolini’s node–place model. However, its underlying database has proven insufficient to draw conclusions regarding urban character and development capacity around stations. This paper focuses on morphological research that aims to improve this database by exploring the density and urban morphology of station areas in the Delta Metropolis beyond readily available statistics, and discusses the methodological and theoretical underpinnings of this survey. The surveying of station areas in 2010 was conducted by a team of six researchers, based on the Spacemate© methodology developed by Berghauser Pont and Haupt. The methodology allows detailed quantitative measurement of the density and spatial characteristics of clearly demarcated urban districts, defining their so-called ‘spatial fingerprint’. The resulting database of 850 districts in 55 station areas has served descriptive goals, strengthening the realism in the SprintCity game, and serves as the database for further establishing the development potential of station areas.
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| 12. |
- Forsemalm, Joakim, 1973, et al.
(författare)
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Urban Qualities: ett kunskapsområde
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Den här kunskapsöversikten är ett försök att utkristallisera relevant forskning såväl som praktisk kunskap för Mistra Urban Futures om urbana kvaliteter. Översikten är kopplad till ett arbete som genomförts under vår och höst 2011 med syfte att skapa underlag för den Strategiska plan som utgör grunden för Mistra Urban Futures planering och aktiviteter. Under våren 2011 arbetade sex grupper med varsitt kunskapsfält – urbana kvaliteter, urban förändring (”transitions”), urbana kulturer, urbana rättigheter, urban tillgänglighet och urban uthållighet. Tanken var att dessa skulle utgöra de sex bärande fokusområdena för centrets verksamhet. Sedermera kom dessa sex områden att slås ihop till tre - FAIR, GREEN och DENSE – vilka nu utgör de tre övergripande problem- och kunskapsområdena för Mistra Urban Futures.
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| 13. |
- Dashti, Fatemeh, 1991
(författare)
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A ground-borne noise prediction model for railway traffic in tunnels in bedrock
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Human life has become more manageable by the expansion of railway lines. However, despite providing convenience, railways increase noise and vibration in residential areas. Vibrations and noise generated by railways may harm human health, cause cosmetic damage and have an adverse impact on the environment. In order to reduce the effects of train-induced noise and vibration, efficient and accurate models for the prediction of ground-borne noise and vibration are required. Various analytical, theoretical, and experimental models have been developed to predict ground-borne noise. There is generally a lack of published information about parameters for ground-borne noise prediction concerning Swedish conditions with bedrock of high quality. Some investigations are reported, and a few consultancy companies have their own developed models, which are generally not publicly available. In fact, overall, the input data used to form these models and the methods of validation are not publicly available. Moreover, the statistical nature of the source and transfer paths requires that uncertainties are accurately handled in the model. This work aims to develop a model for ground-borne noise prediction for underground tunnels, to be used in Swedish Transport Administration projects. The methodology is formulated for three different stages based on precision and available information: location stage, planning stage, and construction stage. The first two stages correspond to planning and designing a railway track. The third stage involves the construction stage where more detailed information may be acquired. The prediction model presented here is developed for Swedish bedrock up to 1 kHz and formulated as a source term and several correction terms. These terms take into account various aspects, including train speed, distance attenuation, ground-to-building coupling, vibration levels on different floors and walls, how the room properties affect sound pressure levels within rooms, and different track treatments. Moreover, uncertainties are estimated using the standard deviation of each term. The required data are gathered from measurements in the Gårda tunnel in Gothenburg combined with existing data from measurements in the Åsa tunnel close to Varberg. As a result, a comprehensive model is suggested for ground-borne noise prediction in Swedish Transport Administration projects. However, the model is still under development, will be sent upon referral, and may undergo improvements.
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| 14. |
- Altintas, Atilla, 1979, et al.
(författare)
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EMD-SVR: A Hybrid Machine Learning Method to Improve the Forecasting Accuracy of Highway Tollgates Traveling Time to Improve the Road Safety
- 2021
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Ingår i: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering. - Cham : Springer International Publishing. - 1867-8211 .- 1867-822X. ; 364 LNICST, s. 241-251
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Konferensbidrag (refereegranskat)abstract
- Tollgates are known as the bottleneck of the highways, which cause long waiting queues in rush-hour times of the day. This brings many undesirable consequences such as higher carbon emission and road safety issues. To avoid this scenario, traffic control authorities need accurate travel time forecasts at tollgates to take effective action to monitor potential traffic load and improve traffic safety. Accurate forecasting of the traffic travel time will help traffic regulators to prevent arising problems by taking action. The main objective of this study is to improve the short-term forecasting (minutes) of the traffic flow on highway tollgates by improving a novel hybrid forecasting method that combines Empirical Mode Decomposition with Support Vector Regression (EMD-SVR). Results claim that compared with SVR, the new proposed hybrid prediction model, EMD-SVR, can effectively improve prediction accuracy. Better forecasting of the traffic load will provide safer roads but will also lower the carbon emissions caused by longer traveling times.
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| 15. |
- Andersson, Petra, et al.
(författare)
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Safe introduction of battery propulsion at sea
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Electric propulsion using batteries as energy storage has the potential to significantly reduce emissions from shipping and thus the environmental impact. The battery type that is currently on the top of the agenda to be used for ship propulsion applications is Li-ion batteries. Li-ion batteries pose different safety issues than e.g. other propulsion technologies and other batteries such as lead-acid batteries. It is essential that the safety level on board, including fire safety, is maintained, when introducing electric propulsion with energy storage in batteries. This report discusses the different regulations and guidelines available today for fire safety of batteries on board in relation to current knowledge about Li-ion batteries. Also fire safety measures available on board ships today and their applicability for Li-ion batteries is discussed, as well as the different test methods available and their applicability. A workshop gathering different stakeholders from Sweden, Norway and Finland identified fire safety as the main challenge for the introduction of battery propulsion at sea. The workshop concluded that future work is desired in order to increase knowledge and to develop publicly available strategies, training and designs.
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| 16. |
- Basso, Rafael, 1979, et al.
(författare)
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Electric Vehicle Routing Problem with Machine Learning for Energy Prediction
- 2021
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Ingår i: Transportation Research Part B: Methodological. - : Elsevier BV. - 0191-2615. ; 145, s. 24-55
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Tidskriftsartikel (refereegranskat)abstract
- Routing electric commercial vehicles requires taking into account their limited driving range, which is affected by several uncertain factors such as traffic conditions. This paper presents the time-dependent Electric Vehicle Routing Problem with Chance- Constraints (EVRP-CC) and partial recharging. The routing method is divided into two stages, where the first finds the best paths and the second optimizes the routes. A probabilistic Bayesian machine learning approach is proposed for predicting the expected energy consumption and variance for the road links, paths and routes. Hence it is possible to consider the uncertainty in energy demand by planning charging within a confidence interval. The energy estimation is validated with data from electric buses driving a public transport route in Gothenburg-Sweden as well as with realistic simulations for 24 hours traffic in the city of Luxembourg connected to a high fidelity vehicle model. Routing solutions are compared with a deterministic formulation of the problem similar to the ones found in the literature. The results indicate high accuracy for the energy prediction as well as energy savings and more reliability for the routes.
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| 17. |
- Berghauser Pont, Meta, 1972, et al.
(författare)
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INTEGRATED URBAN ENVIRONMENT EFFECT ANALYSIS OF INFRASTRUCTURAL TRANSFORMATIONS
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The report presents the method developed within the research project ‘Stadsmiljöanalys- Analys av tätbebyggda miljöer i infrastrukturprojekt’, funded by Trafikverket (Swedish Transport Authority). This project sets up an integrated methodology for analysing and estimating the local impact of road and rail infrastructure projects in urban environments, either by way of new infrastructure or by way of retrofits, focusing on socioeconomic, environmental, and cultural-historical effects. While the focus is on national transport infrastructure investments, the method addresses local effects. This stems from the acknowledgement that each infrastructure investments results in a redistribution of accessibility where increasing accessibility on a regional and interurban scale might create encroachments on a local scale including the reduction of the usability of areas near to the infrastructure due to emissions and noise, risk of accidents, negative impacts on wildlife as well as barrier effects. It is these encroachments this method aims to highlight with the aim to reduce negative trade-offs of new or transformed transport infrastructure and recognize both local opportunities and sensitivities. In this project the direct effects of infrastructure projects in relation to the three perspectives (socioeconomic, environmental, and cultural-historical are described and measured in a precise manner through a series of spatial analyses. The cumulative, indirect, effects and broader consequences are also assessed, in relation to the sustainable development goals. The overall assessment methodology is based on a before-and-after analysis workflow, systematically comparing the existing situation (how it is, how it functions, how it affects people) to the future scenarios proposed by planning. The methodology is showcased using two infrastructural transformations projects in Söderköping and Mölndal, Sweden, as case studies. The overarching goal of the research project is to contribute to an improved integration between infrastructure and local urban areas and communities in projects initiated and developed by the Swedish Transport Authority, Trafikverket. The presented methodology builds on the ILKA (Integrerad landskapskaraktärsanalys) method, currently used by the Swedish Transport Authority. While ILKA focuses mainly on the inventory of the current landscape on a regional scale, this project widens the scope to also address urban areas and to include, besides the ecological descriptions, also socio-economic and cultural-historical analysis that are currently less emphasized. Such an integrated method can improve the ability of the Swedish Transport Authority to develop projects that contribute to sustainable urban development and, furthermore, create a unified work procedure in the organization.
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| 18. |
- Bi, Hui, et al.
(författare)
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Bicycle safety outside the crosswalks: Investigating cyclists' risky street-crossing behavior and its relationship with built environment
- 2023
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Ingår i: Journal of Transport Geography. - : Elsevier BV. - 0966-6923. ; 108
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Tidskriftsartikel (refereegranskat)abstract
- Most bicycle accidents are inextricably bound up with risky riding behaviors, which crossing the street illegally at unprotected mid-block locations is nothing to sneeze at. Compared with cyclists crossing the street at the crosswalk or intersections, there is a huge risk of accidents when they ignore or disobey road rules and across recklessly. Yet, the misbehavior of cyclists is an under-explored area in cyclist research due to the limited availability of detailed cycling data. This study creatively develops a GPS-based detection framework to capture risky street-crossing actions for the cyclists from large-scale bike sharing trajectory data. A data-driven modeling approach, based on structural topic modeling (STM), is developed to reveal the complexity and regularity of cyclists' habitual risky crossing behavior. Since objective built environment is one of the key factors associated with cycling, another goal of this paper is to apply a gradient boosting decision tree (GBDT) model to disentangle how the features of built environment may influence the frequency of risky crossing events. The case study results show that risky street-crossing behavior is prevalent in bicycle traffic – for example, 16.94% of cycling trips are involved in illegal crossing action. Most cyclists engage in illegal crossing behavior at the approximate central part of the streets and during the day, which reveals the presence of heterogeneity over space and time. Strong correlations between commuting activities and risky street-crossing behaviors are identified from topic modeling. Meanwhile, the latent illegal crossing patterns unraveled here highlight that typical reasons for committing the risky riding action include the lure of the travel destination across the road and the inconvenience of riding round in distant legal crossing facilities. GBDT findings provide new insights on the existence of the association between built environment and cyclists' illegal crossing action. The places related employment and catering play a dominant role in contributing risky street-crossing behavior, and the influences of road length, road level, bus stop and metro station are not neglectable. Most built environment attributes show nonlinear correlations with crossing frequency. It is anticipated that this study would successfully shed a first light on the pattern of cyclists' risky street-crossing behavior at the metropolitan scale, and compliment engineering practices to improve crossing behaviors and bicycle safety.
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| 19. |
- Cao, Danni, et al.
(författare)
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Quantification of the impact of traffic incidents on speed reduction: A causal inference based approach
- 2021
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Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575. ; 157
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Tidskriftsartikel (refereegranskat)abstract
- This paper designs a systemic framework to quantify speed reduction induced by traffic incidents using a causal inference framework. The results can provide a reference to traffic managers for evaluating incident severities, thus take proper control measures after the incident in order not to underestimate or overestimate the negative impact. A two-phase scheme is proposed, including impacted region determination and speed reduction quantification. We first propose a Frame Region (FR) method, based on the shockwave propagation, to determine the spatiotemporal impacted region (SIR) using speed map. It is worth-noting that we design a statistical experiment to prove the rationality of congestion threshold selection. Secondly, we introduce a causal inference method for identifying the matched freeway segments. The traffic condition of finally matched freeway segments can be served as non-incident traffic condition of the incident occurred location, which contributes to quantifying the incident impact on speed reduction. We further demonstrate the proposed method in a case study by taking advantage of an incident record and related real freeway speed data in China. An interesting observation is that, along with the freeway segments away from the incident location, the congestion duration time of different freeway segments firstly rises and then decreases. The case study also illustrates the impact of incident on speed lasts almost 3 h and the congestion caused by the incident spreads 11 km, while the average causal effect of incident on all the impacted freeway segments is 42.3 km/h.
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| 20. |
- Castrellon, Juan Pablo, 1989, et al.
(författare)
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Enabling Factors and Durations Data Analytics for Dynamic Freight Parking Limits
- 2023
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; 2677:2, s. 219-234
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Tidskriftsartikel (refereegranskat)abstract
- Freight parking operations occur amid conflicting conditions of public space scarcity, competition with other users, and the inefficient management of loading zones (LZ) at cities’ curbside. The dynamic nature of freight operations, and the static LZ provision and regulation, accentuate these conflicting conditions at specific peak times. This generates supply–demand mismatches of parking infrastructure. These mismatches have motivated the development of Smart LZ that bring together technology, parking infrastructure, and data analytics to allocate space and define dynamic duration limits based on users’ needs. Although the dynamic duration limits unlock the possibility of a responsive LZ management, there is a narrow understanding of factors and analytical tools that support their definition. Therefore, the aim of this paper is twofold. Firstly, to identify factors for enabling dynamic parking durations policies. Secondly, to assess data analytics tools that estimate freight parking durations and LZ occupation levels based on operational and locational features. Semi-structured interviews and focus group analyses showed that public space use assessment, parking demand estimation, enforcement capabilities, and data sharing strategies are the most relevant factors when defining dynamic parking limits. This paper used quantitative models to assess different analytical tools that study LZ occupation and parking durations using tracked freight parking data from the City of Vic (Spain). CatBoost outperformed other machine learning (ML) algorithms and queuing models in estimating LZ occupation and parking durations. This paper contributes to the freight parking field by understanding how data analytics support dynamic parking limits definition, enabling responsive curbside management.
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| 21. |
- Garmabaki, A.H.S., et al.
(författare)
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Assessing climate-induced risks to urban railway infrastructure
- 2024
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Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer. - 0975-6809 .- 0976-4348.
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Tidskriftsartikel (refereegranskat)abstract
- Climate change and its severe impacts pose a number of challenges to transport infrastructure, particularly railway infrastructure, requiring immediate action. A railway system is a linear distributed asset passing different geographical locations and exposed to heterogeneous vulnerabilities under diverse environmental conditions. Furthermore, most of the railway infrastructure assets were designed and built without in-depth analysis of future climate impacts. This paper considers the effects of extreme temperatures on urban railway infrastructure assets, including rail, “switches and crossings”. The data for this study were gathered by exploring various railway infrastructure and meteorological databases over 19 years. In addition, a comprehensive nationwide questionnaire survey of Swedish railway infrastructure, railway maintenance companies, and municipalities has been conducted to assess the risks posed by climate change. A risk and vulnerability assessment framework for railway infrastructure assets is developed. The study shows that track buckling and vegetation fires due to the effect of hot temperatures and rail defects and breakage due to the effect of cold temperatures pose a medium risk. On the other hand, supportability losses due to cold temperatures are classified as high risk. The impact analysis helps infrastructure managers systematically identify and prioritize climate risks and develop appropriate climate adaptation measures and actions to cope with future climate change impacts.
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| 22. |
- Hörteborn, Axel, 1986
(författare)
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Ship Behaviour and Ship Bridge Allision Analysis
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The demand for maritime transport has increased with the growing demand for worldwide trade. This has led to a major increase in maritime traffic and ship sizes over the last decades, which raises the probability of accidents. The methods used in maritime risk assessments today are based on old hypotheses that do not include all data available today. The main objective of this thesis is to develop numerical models and methods for the analysis of what is considered as normal navigation behaviour at sea today and improve the analysis of probability for ship-bridge allisions. The first part of the thesis describes what is considered as normal meeting distance at sea today. This information is later used while identifying failure events to ensure that the event behaviour was not caused by other ships. These few cases are excluded from the methodology since the communication and situational awareness in the situations are not known. However, while studying the probability of ship-bridge accidents, it is also important to understand how waterway restrictions may affect the probability of ship-ship collisions. Therefore, this thesis also includes a study of how the improved knowledge concerning meeting distance could be used in a near ship-ship collision identification model. One of the main findings considering normal meeting distance is that small and large ships meet each other at a similar distance at sea. In the second part of the thesis, a methodology is proposed to estimate the probability of ship-bridge allision. The presented methodology uses Automatic Identification System (AIS) data and a ship manoeuvring simulator to simulate and analyse marine traffic with regards to risks for accidents, such as ship-bridge allisions. A failure event identification method is also presented, which is needed to determine the frequency, duration and behaviour for the accident scenarios. The three events that were modelled and simulated in the simulator were: drifting ship, sharp turning ship and missing turning point. The probability of the different failure events corresponded to previous statistics confirming the AIS-based methodology. This means the methods to obtain the probability and duration of the failure events could be utilised in other areas. The simulation methodology was confirmed with the probability of grounding in the Great Belt VTS area. This thesis firstly contributes to a better understanding of the modelling of probability for ship-bridge allisions. This will support bridge-building engineers who need to take into account accidental loads from ship-bridge allision while designing bridges. Secondly, this thesis also contributes to a better representation of normal behaviour at sea, which is used both in fairway designs and in estimations of ship-ship collisions.
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| 23. |
- Janné, Mats, 1979-, et al.
(författare)
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Smart Construction Logistics Governance : A systems view of construction logistics in urban development
- 2021
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Ingår i: Proceedings of the 57th ISOCARP World Planning Congress. - : ISOCARP. - 9789075524697 ; , s. 1165-1174
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Konferensbidrag (refereegranskat)abstract
- To reduce disturbances and impact from construction transports during urban development, logistics flows need to be managed and controlled efficiently. One way to do so is using construction logistics setups. However, these rarely take both initiator and end-user perspectives into consideration. The paper builds on a longitudinal multiple-case study with cases from Belgium, Norway, and Sweden. The cases provide insights on different tools and approaches for gathering stakeholder input, simulation and forecasting of transport volumes, what type of services are needed in urban construction projects, and different governance measures and incentives. A cross-case analysis was performed to find similarities and differences between the countries. The result of the study is a conceptual framework, presenting a systems overview of the decision routes in urban development linked to construction logistics.
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| 24. |
- Karlsson, Tobias, 1984, et al.
(författare)
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Tools to prevent waste in material flow in housing projects
- 2014
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Ingår i: Proceedings of the 17th International Symposium on Advancement of Construction Management and Real Estate (CRIOCM 2012). - Berlin, Heidelberg : Springer Berlin Heidelberg. ; , s. 757-768
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Konferensbidrag (refereegranskat)abstract
- There is a lack of apartments in major Scandinavian cities. At the same time, there is a general opinion in media that the costs for housing production are too high. Studies indicate that waste, in the lean perspective, is in the range of 30-35% of the project cost, excluding costs for land. Among initiatives for reducing waste are tools to prevent waste in material flows. This paper presents a case study in which a logistics company, a medium-sized contractor and a material supplier collaborated to develop tools for improving the material flow on the construction site. Initially, nine tools used for preventing waste in material flow is presented; logistic analysis, demand profile, process map, specifications for building hoist, delivery plan, responsibility during material handling, location in apartments, quantification of materials and control of deliveries. Then, each tool is evaluated concerning what kind of waste is reduced. Examples from a residential building project with 163 apartments are given. The costs associated with enhanced material logistics in this specific project were approximately SEK 130 per m2, which is equal to RMB 115 per m2. This covers the enhanced handling of 80% of the materials. It’s expected within the case project that enhanced logistics with support by the nine tools has a potential of giving a 2-5 times return on the investment. The conclusion is that material logistics requires good planning and structure in order to be effective and succeed in minimizing waste.
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| 25. |
- Khosravi, Mahdi, 1988-, et al.
(författare)
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Assessment of Railway Track Preventive and Corrective Tamping Recovery
- 2023
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Konferensbidrag (refereegranskat)abstract
- Railway track, as a critical infrastructure, plays a significant role in freight transportation. However, Railway track degrades with age and usage and can impact negatively track availability and safety. Tamping actions are used to rejuvenate the degradation and recover the functionality of the track to an acceptable level. Tamping actions are performed in a form of preventive and corrective regimes. In performing an effective tamping regime, the recovery of both preventive and corrective tamping should be taken into account. In addition, the occurrence of isolated defects should be considered. By combining the recovery model with the degradation model, the long-term behavior of the track geometry can be predicted, and an accurate estimation of tamping needs can be provided, leading to optimum tamping scheduling. In this study, the effects of tamping recovery are modeled for both preventive and corrective strategies. For this aim, the values of both standard deviation (SD) and isolated defects have been predicted and their values before tamping are used as explanatory variables in a multivariable regression model. Finally, the effect of tamping recovery on the values of both SD and isolated defects is estimated. A case study is performed on a heavy haul line located in Sweden’s rail network to evaluate the performance of the proposed multivariable regression model. Observations showed that the model and its coefficients are significant with P-values close to zero, and the R-squared value suggests that the model explains approximately 70% of the variability in the response variable recovery.
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