| 1. |
- Whitehead, Jake, 1989-
(författare)
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Energy Efficient Vehicle Policy: Lessons Learnt : An analysis of the effects of incentive policies on the demand, usage and pricing of energy efficient vehicles.
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Encouraging the uptake of energy efficient vehicles (EEVs) is an aspiration of critical importance in a day and age in which we are confronted with the increasingly dire consequences of human behaviour on our planet, and on the planet for generations to come. The transport sector is one of the highest contributors of anthropogenic greenhouse gas emissions, whilst pollution from this sector is responsible for a large proportion of human deaths each and every year. Given the severity of these issues, it is more important than ever for policy-makers, and researchers alike, to encourage a transition within the community towards more sustainable lifestyles. Transportation is key to this change.As a service that every human being uses, almost every day of his or her life, the transport sector presents a unique opportunity for behavioural change. Through efficient and targeted policies, consumers can be incentivised to make more sustainable transport choices and to consider the consequences of their own actions. Foremost amongst these initiatives is that of encouraging a transition towards energy efficient vehicles.This thesis has been produced in order to shed further light on issues affecting this transition. In particular for policy-makers, this document includes a series of recommendations based on prevailing findings in the current literature, in addition to the novel and significant findings of this research effort. These include the various lessons learnt from government policies that have already been implemented in regions around the globe.As a thesis by publication, this document consists of four research articles that investigate factors affecting the EEV market, specifically in terms of: consumer demand, vehicle usage and product pricing. A number of other demographic and economic factors have also been examined, including the role of economies-of-scale.
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| 2. |
- Dharmowijoyo, Dimas Bayu Endrayana, 1978-
(författare)
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The complexity and variability of individuals' activity-travel patterns in Indonesia
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Considering an individual’s day-to-day variability of activity-travel patterns will provide a more complete description of how an individual behaves to adapt the changing constraints and resources on different days. Without this day-to-day variability understanding, the individual’s behaviour would not be fully grasped and any suggested policy, planning and development would not completely achieve their desired objectives. The day-to-day behaviour is a subject to an interaction between individual’s needs and time-space constraints. The availability of ‘external’ resources (e.g., disposable income, built environment accessibility, and access to different travel mode/s) gives more opportunities for some individuals to participate in certain activities and/or trips than others. The constraints do not only consider budget and time constraints, but also include how an individual associates with other individuals and materials, and complies with any given authorities’ rules and regulations. The needs-constraints interaction also unveils some endogeneities which may not be captured by microeconomic and attitude theories. Failing to understand these interactions will underestimate the individual’s complex decision making process for performing certain behaviour.The constraints are not solely about physical constraints and instrumental factors, such as travel mode availability, time and cost. It is also influenced by individual’s non-instrumental variables, such as motivation, volition and habits. Currently there is a lack of knowledge how these non-instrumental variables are interacting and influencing the constraints to shape the individual’s travel behaviour. The implementation of certain activity-travel policy which only focuses in giving more opportunities to an individual within time and space resources without considering an individual’s attitude and/or habit may not be well accepted and followed by member of public. Moreover, the integration also reveals how an individual puts different priority on different potential activities based on the how an individual allocates/does not allocate time in engaging certain activities when having strong commitment and intention. In addition, including an individual’s health condition in the analysis may help in coordinating certain public health related policy with activity-travel policy.This thesis includes six papers which investigated the factors described above. The first three papers investigated how activity participation and built environment variables which can represent individuals’ constraints explain the day-to-day variability of individuals’ behaviours. Furthermore, the fourth and fifth paper explored the interaction between individuals’ time-use and activity participation, subjective characteristics and health factors. Lastly, the sixth paper examined how the time-space constraints and health condition explain the degree of variability in individuals’ multi-facet and multi-dimensional activity-travel patterns using sequential alignment method.
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| 3. |
- Fadaei Oshyani, Masoud, 1985-
(författare)
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New Opportunities in Urban Transport Data : Methodologies and Applications
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The deployment of Information and Communication Technologies (ICT) is growing in transportation which may contribute to a more efficient and effective service. The data acquired from ICT based systems could be used for many purposes such as statistical analysis and behavior learning and inference. This dissertation addresses the question of how transportation data that was collected for a specific application can be used for other applications. This thesis consists of five separate papers, each addressing a subset of the topic.The first paper estimates a route choice model using sparse GPS data. This paper demonstrates the feasibility of an Indirect Inference based estimator in a model with random link costs, allowing for a natural correlation structure across paths, where the full choice set is considered.The second paper presents an estimator for the mean speed and travel time at network level based on indirect inference when the data are spatially and temporally sparse.The third paper proposes an evaluation framework which outlines a systematic process to quantify and assess the impacts of public transport preferential measures on service users and providers in monetary terms, using public transport data sources.In the fourth and fifth papers, a methodology is developed and implemented for integrating different prediction models and data sources while satisfying practical requirements related to the generation of real-time information. Then the performance of the proposed prediction method is compared with the prediction accuracy obtained by the currently deployed methods.
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| 4. |
- Jonsson, R. Daniel, 1972-
(författare)
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Analysing Sustainable Urban Transport and Land-Use : Modelling tools and appraisal frameworks
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sustainable development and climate change is high on the agenda for most cities around the world today. Urban transport is at the heart of these changes. Increasingly, it is recognised that not only is the emission of pollutants and greenhouse gases a problem, but also the detrimental effects of congestion and social exclusion. In order to address these issues, it will be necessary for cities to make strategic long term decisions regarding the future infrastructure and land use, not only in terms of what will be built, but also on measures that affect how these systems are used.This thesis is focused on the decision support tools that we need in order to make well informed decisions. Models that predict the performance of future scenarios, and appraisal frameworks that help evaluate whether these outcomes are desirable or not. The first two papers experiment with different ways of bringing some aspects of sustainability into the appraisal frameworks used to analyse long term strategies. Paper I addresses intergenerational fairness, and Paper II focuses on the emission of greenhouse gases. Paper III develops a model, Scapes, that can help us to better understand the daily travel behaviour, through an activity based approach. By explicitly modelling space-time constraints, and travel time uncertainty in a microeconomic framework, we can get a better understanding of how people can respond to, and value, changes in the transport system. Papers IV and V describe a new integrated land use and transport model, LandScapes.The policy implications from the studies in Papers I, II, and V are that it will be very difficult for Stockholm to reduce its emissions of CO2. Particularly, predicted economic and population growth will inevitably lead to more transport. It is likely that a range of different policies will be necessary to solve that problem. At the same time, we must not forget that decreasing CO2 emissions, although important, is not the only objective Stockholm has. To cope with the increasing travel demand from a growing population, it may well be necessary to build new infrastructure as well. This thesis does not prescribe any such relative valuation between conflicting objectives. It only helps bring them to the fore.
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| 5. |
- Myrhammar, Anders, 1987-
(författare)
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Investigations of chemical and enzymatic functionalization of affinity proteins
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- AbstractAffinity proteins are important reagents in research, diagnostics and therapeutic settings. The focus of this thesis has been on investigating different chemical and enzymatic strategies for engineering of affinity proteins to generate affinity reagents with improved or changed functionality. The modifications introduced in affibodies, representing a class of small, three-helix engineered scaffold proteins, and antibodies were selected and implemented through rational design, using a combination of solid phase peptide synthesis, genetic engineering and enzymatic conjugation, depending on the case.In a first study, thioether crosslinks were introduced between internally positioned lysines and cysteines of the human epidermal growth factor receptor (hEGFR)-targeting affibody ZEGFR:1907, to test the possibility to increase the proteolytic stability of the affibody scaffold. Three different variants of crosslinked affibodies were produced, containing one or two crosslinks. All three variants showed similar affinities to EFGR, and secondary structure contents, as the unmodified control protein. The crosslinked affibodies were challenged with the endopeptidases pepsin, found in the stomach, and trypsin and chymotrypsin, found in the gut. All affibodies showed improved stability towards at least one of the proteases, but the largest improvement was seen for the affibody harboring two crosslinks, which displayed the greatest stability in both assays.Improvement in proteolytic stability of affibodies was further explored. In another study a sortase A-catalyzed intramolecular head-to-tail conjugation of the dimeric human epidermal growth factor 2 (HER2)-targeting affibody (ZHER2:342)2 was performed. Analysis showed no change in α-helicity for the cyclic dimer compared to the linear control, and a slight increase in melting temperature. Interestingly, in contrast to the linear variant, the cyclic dimer showed no signs of proteolytic degradation after 60 min exposure to the exopeptidase carboxypeptidase A.The ability to change protein functionality by chemical modification was explored in two studies. The immunoglobulin-binding Z domain, from which the affibody scaffold is derived, was used as a model protein in one study, where light-induced affinity modulation was investigated. An azobenzene switch that isomerizes from a trans to a cis state was introduced end-to-end to one of the helices in three different designs of the Z domain. The conformational change induced by isomerization was hypothesized to be large enough to cause a loss in binding affinity in the conjugated affibody, which was tested in an affinity chromatography assay in which one of the affibodies captured to an IgG-sepharose column showed loss of affinity during illumination.Peptide nucleic acid (PNA) probes have previously successfully been used for selective hybridization between the primary, tumor-targeting agent and the secondary agent in a pretargeting set-up for in vivo tumor imaging or directed therapy. In a last study, a Z domain-PNA conjugate produced via sortase A-mediated conjugation was photoconjugated to a lactosaminated antibody for possible use as an in vivo clearing agent for clearance of excess of primary probes via an hepatic route. The clearing agent showed partial success in a mouse model but the concept needs further work.The work in this thesis shows the diverse possibilities available for changing the functionality of affinity proteins through chemical and enzymatic methods for different applications, and provides a framework for potential further improvement of both affibody and antibody functionality.
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| 6. |
- Nordström, Maria
(författare)
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Time, justice and the future of mobility : Essays in philosophy of transport
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis in philosophy consists of an introduction and five papers on three themes related to transport: valuations of time, the metric of transport justice, and future mobility solutions. The first paper analyses the properties of time as an economic resource taking into account literature on behaviour concerning time. The intent is to add to the understanding of the underlying assumption of transferability between time and money in the context of transportation.The second paper is on the metric of transport justice. If we are concerned with distributive justice in the context of transportation, what type of good is being distributed? So far, most of the transport literature on transport justice takes accessibility to be the most appropriate metric. However, I argue that many operationalisations of accessibility are insufficient as metrics of justice. They are both too narrow and exclude relevant burdens of transportation. Additionally, accessibility can be achieved by other, non-travel-based means. I end by formulating tentative criteria for an alternative metric of transport justice. The third paper considers temporal justice in the context of transportation. Building on an argument against the claim of substitutability between time and money, I argue that temporal perspectives have been overlooked in the literature on transport justice. In part, this might be due to accessibility being the established metric of justice. Most common measures of accessibility do not capture temporal constraints and might consequently not capture temporal inequalities. Based on the case of gender differences in travel patterns and behaviour, I argue that an alternative account of the appropriate metric of transport justice is needed to capture temporal constraints and reflect gender inequalities sufficiently. The fourth paper argues that the diversity of possible mobility solutions based on self-driving vehicles has been somewhat overlooked in the current literature on the value of travel time. Thus, the complexity of valuing travel time for self-driving vehicles has not been fully addressed. The paper consists of a morphological analysis of the parameters that might impact the value of travel time for self-driving vehicles and a deeper analysis of five plausible self-driving vehicle mobility concepts. It is claimed that not all such concepts can be easily mapped into transport modes. It might be more appropriate to differentiate the value of travel based on travel characteristics.The fifth paper is a literature review of work on attitudes toward automation technology, specifically self-driving vehicles. In particular, I examine the narratives and values related to gender. Generally, women tend to be more sceptical of the prospect of automated vehicles. The review found that this tendency is often explained by women being more risk-averse and less tech-savvy. Moreover, the policy recommendations in the examined literature based focus on educational efforts. Such perspectives can downplay or neglect valid reasons why women are less enthusiastic. Moreover, needs related to women's specific travel patterns might not be considered in the design and planning process. In conclusion, more awareness in needed of the gender differences, needs and expectations to ensure that future transport solutions are designed with everyone in mind.
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| 7. |
- Whitehead, Jake, 1989-
(författare)
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Making the Transition to a ‘Green’ Vehicle Fleet : An analysis of the choice and usage effects of incentivising the adoption of low-emission vehicles
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Making the transition to a ‘green’ vehicle fleet is a noteworthy endeavour for any policy maker. Under the current global pressures of increasing greenhouse gas emissions there is no doubt that all efforts that can be adopted in order to improve the sustainability of our cities should be explored. In saying this however, it is crucial when designing such policies that proper cost-benefit analyses are performed; taking into account the potentially negative rebound effects of such measures and understanding which individuals are affected by such policies.Comprising of two papers, this thesis analyses the choice and usage effects of an exemption for low-emission vehicles (LEVs) from Stockholm’s congestion charging scheme. The ambition of this study has been to understand: the extent to which this exemption policy influenced the demand for LEVs; which individuals were targeted; whether the policy led to any rebound effects (increased LEV usage); and ultimately what the effect of this policy was in terms of changes in emissions.Paper I employs a MNL model to examine the demographics of those individuals who purchased an LEV in Stockholm during 2008 and the extent to which the exemption policy influenced this demand. It was found that those owners living within the cordon but who commuted across the boundary for work had the highest propensity towards purchasing an exempt LEV. The exemption policy was found to have increased the share of exempt LEVs by 1.9% to 18.9% in total, corresponding to an additional 550 exempt LEV purchases in 2008 due to this policy.In Paper II, the differences in annual usage rates between demographically-similar LEV and conventional vehicle owners are calculated using propensity score matching in order to control for potential self-selection effects. Through this procedure it was found that the direct emissions of vehicle owners who adopted LEVs were reduced by 52.4%. Although the exemption policy was partially responsible for increasing the number of LEVs, it also appears to have encouraged an increase in annual usage, leading to rebound effects that offset the potential reduction in emissions (increase in LEV usage: 12.2% for owners that lived inside / worked outside cordon; 8.5% for owners that lived outside / worked inside cordon).Through the analysis detailed in the two papers of this thesis, the effects of an incentive based policy in Stockholm upon both the demand and usage of LEVs have been highlighted. The benefits, as well as the possible complications of this initiative have also been discussed, in the hope of enlightening policy makers to ensure that potential emissions reductions are maximised for similar policy initiatives in the future. With personal vehicles likely to continue dominating the share of home-work trips over the coming years, cities must continue their efforts in encouraging the transition to a ‘green’ vehicle fleet. It is important, however, that these efforts lead to incentive based policies that are balanced, reasonable, and designed to minimise potentially substantial rebound effects.
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| 8. |
- Almström, Peter, 1980-
(författare)
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Three essays on transport CBA uncertainty
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cost Benefit Analysis (CBA) has for a long time been used in transport planning, but it is often questioned. One main argument against CBA is that the results depend largely on assumptions regarding one or a few input factors, as for example the future fuel price or valuation of CO2 emissions.The three papers included in this thesis investigate some aspects of uncertainty in transport CBA calculations. The two first papers explore how changes in input data assumptions affect the CBA ranking of six rail and road investments in Stockholm. The first paper deals with the effect of different land-use assumptions while the second deals with the influence of economic growth, driving cost and public transport fare. The third paper investigates how alternative formulations of the public transport mode choice and route choice affect travel flows, ticket revenues and consumer surplus. These are important factors previously known to affect CBA results.The findings of the first two papers suggest that CBA results are robust concerning different land-use scenarios and single input factors. No change in rank between a road and a rail object is observed in the performed model calculations, and only one change between two road objects. The fact that CBA results seem robust regarding input assumptions supports the use CBA as a tool for selecting transport investments. The results in the third paper indicate that if there is detailed interest in, for example, number of boardings and ticket income from a certain transit line, or the total benefit of a price change, a more detailed formulation of the public transport mode choice and route choice will provide more reliable results. On the other hand, this formulation requires substantially more data on the transit line and price structure than the conventional formulation used in Swedish transport planning, especially in areas with many different pricing systems.
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| 9. |
- Fadaei Oshyani, Masoud
(författare)
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Two papers on consistent estimation of a route choice model and link speed using sparse GPS data
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Global Positioning System and nomad devices are increasingly used to provide data from individuals in urban traffic networks. In these two papers we focus on consistent estimators of a route choice model and link speed.In many different applications, it is important to predict the continuation of an observed path, and also, given sparse data, predict where the individual (or vehicle) has been. Estimating the perceived cost functions is a difficult statistical estimation problem, for different reasons. First, the choice set is typically very large.Second, it may be important to take into account the correlation between the (generalized) costs of different routes, and thus allow for realistic substitution patterns. Third, due to technical or privacy considerations, the data may be temporally and spatially sparse, with only partially observed paths. Finally, the position of vehicles may have measurement errors. We address all these problems using an indirect inference (II) approach. We demonstrate the feasibility of the proposed estimator in a model with random link costs, allowing for a natural correlation structure across paths, where the full choice set is considered.In the second paper, we develop an estimator for the mean speed and travel time based on indirect inference when the data are spatially and temporally sparse. With sparse data, the full path of vehicles are not observed, which is typically addressed using map matching techniques.First, we show how speed can be estimated using an auxiliary model which includes map matching and a model of route choice. Next, we further develop the estimator and show how both speed and the route choice model can be jointly estimated by using iteration between an II estimator of speed and the II estimator of the route choice model (developed in Paper I). Monte Carlo evidence is provided which demonstrates that the estimator is able to accurately estimate both speed and parameters of the route choice model.
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| 10. |
- Habibi, Shiva, 1978-
(författare)
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Prediction-driven approaches to discrete choicemodels with application to forecasting car typedemand
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Models that can predict consumer choices are essential technical support fordecision makers in many contexts. The focus of this thesis is to address predictionproblems in discrete choice models and to develop methods to increase the predictivepower of these models with application to car type choice. In this thesis we challengethe common practice of prediction that is using statistical inference to estimateand select the ‘best’ model and project the results to a future situation. We showthat while the inference approaches are powerful explanatory tools in validating theexisting theories, their restrictive theory-driven assumptions make them not tailormadefor predictions. We further explore how modeling considerations for inferenceand prediction are different.Different papers of this thesis present various aspects of the prediction problemand suggest approaches and solutions to each of them.In paper 1, the problem of aggregation over alternatives, and its effects on bothestimation and prediction, is discussed. The focus of paper 2 is the model selectionfor the purpose of improving the predictive power of discrete choice models. Inpaper 3, the problem of consistency when using disaggregate logit models for anaggregate prediction question is discussed, and a model combination is proposedas tool. In paper 4, an updated version of the Swedish car fleet model is appliedto assess a Bonus-Malus policy package. Finally, in the last paper, we present thereal world applications of the Swedish car fleet model where the sensitivity of logitmodels to the specification of choice set affects prediction accuracy.
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