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Publications (10 of 99) Show all publications
Saleem, M., Västberg, O. B. & Karlström, A. (2018). An Activity Based Demand Model for Large Scale Simulations. In: The 9th International Conference on Ambient Systems, Networks and Technologies (ANT 2018) / The 8th International Conference on Sustainable Energy Information Technology (SEIT-2018) / Affiliated Workshops: . Paper presented at 9th International Conference on Ambient Systems, Networks and Technologies, ANT 2018, Porto, Indonesia, 8 May 2018 through 11 May 2018, (pp. 920-925). Elsevier, 130
Open this publication in new window or tab >>An Activity Based Demand Model for Large Scale Simulations
2018 (English)In: The 9th International Conference on Ambient Systems, Networks and Technologies (ANT 2018) / The 8th International Conference on Sustainable Energy Information Technology (SEIT-2018) / Affiliated Workshops, Elsevier, 2018, Vol. 130, p. 920-925Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents the ongoing development of SCAPER, a random utility based travel demand model that consistently incorporates time decisions. The paper focusses on how SCAPER can be used for large scale simulations, and more specifically: 1. How computational speed of SCAPER is improved using sampling of locations, and how it influences the simulation results. 2. Interfacing SCAPER to MATSim simulation framework, and estimating the SCAPER model with travel times and travel costs produced by the simulation of Stockholm demand (simulated) over Stockholm network using MATSim. 3. Preliminary results from 1 and 2.

Place, publisher, year, edition, pages
Elsevier, 2018
Series
Procedia Computer Science, ISSN 1877-0509 ; 130
Keywords
dynamic discrete choice model, estimation, MATSim, sampling, SCAPER, travel demand model
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-238360 (URN)10.1016/j.procs.2018.04.090 (DOI)2-s2.0-85051261611 (Scopus ID)
Conference
9th International Conference on Ambient Systems, Networks and Technologies, ANT 2018, Porto, Indonesia, 8 May 2018 through 11 May 2018,
Note

QC 20181812

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-12Bibliographically approved
Zimmermann, M., Västberg, O. B., Frejinger, E. & Karlström, A. (2018). Capturing correlation with a mixed recursive logit model for activity-travel scheduling. Transportation Research Part C: Emerging Technologies, 93, 273-291
Open this publication in new window or tab >>Capturing correlation with a mixed recursive logit model for activity-travel scheduling
2018 (English)In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 93, p. 273-291Article in journal (Refereed) Published
Abstract [en]

Representing activity-travel scheduling decisions as path choices in a time-space network is an emerging approach in the literature. In this paper, we model choices of activity, location, timing and transport mode using such an approach and seek to estimate utility parameters of recursive logit models. Relaxing the independence from irrelevant alternatives (IIA) property of the logit model in this setting raises a number of challenges. First, overlap in the network may not fully characterize perceptual correlation between paths, due to their interpretation as activity schedules. Second, the large number of states that are needed to represent all possible locations, times and activity combinations imposes major computational challenges to estimate the model. We combine recent methodological developments to build on previous work by Blom Vastberg et al. (2016) and allow to model complex and realistic correlation patterns in this type of network. We use sampled choices sets in order to estimate a mixed recursive logit model in reasonable time for large-scale, dense time-space networks. Importantly, the model retains the advantage of fast predictions without sampling choice sets. In addition to estimation results, we present an extensive empirical analysis which highlights the different substitution patterns when the IIA property is relaxed, and a cross-validation study which confirms improved out-of-sample fit.

Place, publisher, year, edition, pages
Pergamon Press, 2018
Keywords
Travel demand modeling, Activity-travel scheduling, Mixed recursive logic, Activity network, Mode choice
National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:kth:diva-234636 (URN)10.1016/j.trc.2018.05.032 (DOI)000442173400016 ()2-s2.0-85048520868 (Scopus ID)
Funder
Swedish National Infrastructure for Computing (SNIC)National Supercomputer Centre (NSC), Sweden
Note

QC 20180912

Available from: 2018-09-12 Created: 2018-09-12 Last updated: 2018-09-12Bibliographically approved
Dharmowijoyo, D. B. E., Susilo, Y. O. & Karlström, A. (2017). Analysing the complexity of day-to-day individual activity-travel patterns using a multidimensional sequence alignment model: A case study in the Bandung Metropolitan Area, Indonesia. Journal of Transport Geography, 64, 1-12
Open this publication in new window or tab >>Analysing the complexity of day-to-day individual activity-travel patterns using a multidimensional sequence alignment model: A case study in the Bandung Metropolitan Area, Indonesia
2017 (English)In: Journal of Transport Geography, ISSN 0966-6923, E-ISSN 1873-1236, Vol. 64, p. 1-12Article in journal (Refereed) Published
Abstract [en]

Using a panel regression model and a multidimensional three-week household time-use and activity diary, this study analyses the complexity of the day-to-day variability in individuals' activity-travel patterns by applying a multidimensional sequence alignment model. It is found that the variability between weekend and weekday pairs is much greater than between weekday-weekday pairs or weekend-weekend pairs. The variability of other household members' activity-travel patterns is found to significantly influence an individual's activity-travel patterns. The results also show that the variability in the activity-travel patterns of workers and students is greater when conducting a particular discretionary activity on weekdays. Due to performing discretionary activities more often and for longer, non-workers tend to have more predictable activity-travel patterns. Undertaking multitasking activities within different activities on weekdays significantly impacted the different degrees of variability in an individual's activity-travel patterns. Having different health and built environment characteristics also corresponds with different degrees of predictability of the activity-travel patterns, particularly in the worker/student case.

National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-218234 (URN)10.1016/j.jtrangeo.2017.08.001 (DOI)000414885200001 ()2-s2.0-85027346442 (Scopus ID)
Note

QC 20171128

Available from: 2017-11-28 Created: 2017-11-28 Last updated: 2017-11-28Bibliographically approved
Zhang, W., Sundberg, M. & Karlström, A. (2017). Platoon coordination with time windows: An operational perspective. In: 20th EURO Working Group on Transportation Meeting, EWGT 2017, 4-6 September 2017, Budapest, Hungary: . Paper presented at 20th EURO Working Group on Transportation Meeting, EWGT 2017, 4-6 September 2017, Budapest, Hungary (pp. 357-364). Elsevier, 27
Open this publication in new window or tab >>Platoon coordination with time windows: An operational perspective
2017 (English)In: 20th EURO Working Group on Transportation Meeting, EWGT 2017, 4-6 September 2017, Budapest, Hungary, Elsevier, 2017, Vol. 27, p. 357-364Conference paper, Published paper (Refereed)
Abstract [en]

It has been reported that platooning has the potential of saving fuel and increasing traffic throughput. We formulate a platoon coordination problem with soft time windows as a mixed-integer linear programming problem and solve it with exact solutions. The objective function consists of operation costs, schedule miss penalties and fuel costs. In the numerical example, a Swedish highway network model is used and the computation result shows that, for 21 vehicles, the total cost can be reduced by 3.5% when the optimal preferred arrival times are chosen. A random disturbance is then added to the optimal time windows and the optimal result shows great sensitivity with respect to the disturbance. When the mean of the disturbance becomes larger than 10 minutes, more than half of the platooning benefits will be lost. The study also analyzes the change of different cost compositions as disturbance increases.

Place, publisher, year, edition, pages
Elsevier, 2017
Series
Transportation Research Procedia, ISSN 2352-1457 ; 27
Keywords
freight transportation, Heavy-duty vehicle platooning, operational cost, time window
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-222070 (URN)10.1016/j.trpro.2017.12.129 (DOI)2-s2.0-85039950890 (Scopus ID)
Conference
20th EURO Working Group on Transportation Meeting, EWGT 2017, 4-6 September 2017, Budapest, Hungary
Note

QC 20180131

Available from: 2018-01-31 Created: 2018-01-31 Last updated: 2019-05-17Bibliographically approved
Liu, C., Susilo, Y. & Karlström, A. (2017). Weather variability and travel behaviour - what we know and what we do not know. Transport reviews, 37(6), 715-741
Open this publication in new window or tab >>Weather variability and travel behaviour - what we know and what we do not know
2017 (English)In: Transport reviews, ISSN 0144-1647, E-ISSN 1464-5327, Vol. 37, no 6, p. 715-741Article in journal (Refereed) Published
Abstract [en]

Given that severe weather conditions are becoming more frequent, it is important to understand the influence of weather on an individual's daily activity-travel pattern. While some previously rare events are becoming more common, such as heavy rain, unpredicted snow, higher temperatures, it is still largely unknown how individuals will change and adapt their travel patterns in future climate conditions. Because of this concern, the number of research studies on weather and travel behaviour has increased in recent decades. Most of these empirical studies, however, have not used a cost-benefit analysis (CBA) framework, which serves as the the main tool for policy evaluation and project selection by stakeholders. This study summarises the existing findings regarding relationships between weather variability and travel behaviour, and critically assesses the methodological issues in these studies. Several further research directions are suggested to bridge the gap between empirical evidence and current practices in CBA.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2017
Keywords
Weather, travel behaviour, large-scale transport model, transport policy, cost-benefit analysis
National Category
Climate Research
Identifiers
urn:nbn:se:kth:diva-222220 (URN)10.1080/01441647.2017.1293188 (DOI)000422941000006 ()2-s2.0-85013439262 (Scopus ID)
Note

QC 20180205

Available from: 2018-02-05 Created: 2018-02-05 Last updated: 2018-02-05Bibliographically approved
Dharmowijoyo, D. B. E., Susilo, Y. O. & Karlström, A. (2016). Day-to-day variability in travellers' activity-travel patterns in the Jakarta metropolitan area. Transportation, 43(4), 601-621
Open this publication in new window or tab >>Day-to-day variability in travellers' activity-travel patterns in the Jakarta metropolitan area
2016 (English)In: Transportation, ISSN 0049-4488, E-ISSN 1572-9435, Vol. 43, no 4, p. 601-621Article in journal (Refereed) Published
Abstract [en]

Using four consecutive days of SITRAMP 2004 data from the Jakarta metropolitan area (JMA), Indonesia, this study examines the interactions between individuals’ activity-travel parameters, given the variability in their daily constraints, resources, land use and road network conditions. While there have been a significant number of studies into day-to-day variability in travel behaviour in developed countries, this issue is rarely examined in developing countries. The results show that some activity-travel parameter interactions are similar to those produced by travellers from developed countries, while others differ. Household and individual characteristics are the most significant variables influencing the interactions between activity-travel parameters. Different groups of travellers exhibit different trade-off mechanisms. Further analyses of the stability of activity-travel patterns across different days are also provided. Daily commuting time and regular work and study commitments heavily shape workers’ and students’ flexibility in arranging their travel time and out-of-home time budget, leading to more stable daily activity-travel patterns than non-workers.

Place, publisher, year, edition, pages
Springer Science+Business Media B.V., 2016
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-179119 (URN)10.1007/s11116-015-9591-4 (DOI)000379028700002 ()2-s2.0-84925250842 (Scopus ID)
Note

QC 201512

Available from: 2015-12-10 Created: 2015-12-10 Last updated: 2017-12-01Bibliographically approved
Chengxi, L., Susilo, Y. O. & Karlström, A. (2016). Estimating changes in transport CO2 emissions due to changes in weather and climate in Sweden. Transportation Research Part D: Transport and Environment, 49, 172-187
Open this publication in new window or tab >>Estimating changes in transport CO2 emissions due to changes in weather and climate in Sweden
2016 (English)In: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 49, p. 172-187Article in journal (Refereed) Published
Abstract [en]

There is a considerable body of studies on the relationship between daily transport activities and CO2 emissions. However, how these emissions vary in different weather conditions within and between the seasons of the year is largely unknown. Because individual activity–travel patterns are not static but vary in different weather conditions, it is immensely important to understand how CO2 emissions vary due to the change of weather. Using Swedish National Travel Survey data, with emission factors calculated through the European emission factor model ARTEMIS, this study is a first attempt to derive the amount of CO2 emission changes subject to the change of weather conditions. A series of econometric models was used to model travel behaviour variables that are crucial for influencing individual CO2 emissions. The marginal effects of weather variables on travel behaviour variables were derived. The results show an increase of individual CO2 emissions in a warmer climate and in more extreme temperature conditions, whereas increasing precipitation amounts and snow depths show limited effects on individual CO2 emissions. It is worth noting that the change in CO2 emissions in the scenario of a warmer climate and a more extreme temperature tends to be greater than the sum of changes in CO2 emissions in each individual scenario. Given that a warmer climate and more extreme weather could co-occur more frequently in the future, this result suggests even greater individual CO2 emissions than expected in such a future climate.

Keywords
CO2 emission, Emission factor, Weather and climate, Climate change, Meteorology, Transportation, Econometric model, Emission factor model, Emission factors, Extreme temperatures, Marginal effects, National travel surveys, Transport activity, Travel behaviour, Carbon dioxide
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-195190 (URN)10.1016/j.trd.2016.09.004 (DOI)000389390600013 ()2-s2.0-84988473735 (Scopus ID)
Note

QC 21061202

Available from: 2016-12-02 Created: 2016-11-02 Last updated: 2017-11-29Bibliographically approved
Dharmowijoyo, B. E., Susilo, Y. O., Karlström, A. & Adiredja, L. S. (2015). Collecting a multi-dimensional three-weeks household time-use and activity diary in the Bandung Metropolitan Area, Indonesia. Transportation Research Part A: Policy and Practice, 80, 231-246, Article ID 1641.
Open this publication in new window or tab >>Collecting a multi-dimensional three-weeks household time-use and activity diary in the Bandung Metropolitan Area, Indonesia
2015 (English)In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 80, p. 231-246, article id 1641Article in journal (Refereed) Published
Abstract [en]

This paper describes a comprehensive panel data collection and analysis at household level, including detailed travel behaviour variables and comprehensive in-home and out-of-home activities, individual cognitive habits and affective behaviours, the rate of physical activity, as well as health related quality of life (QoL) information in the Bandung Metropolitan Area (BMA) of Indonesia. To our knowledge, this is the first attempt to collect an individual's activity diary over an extended period as it captures the multi-tasking activities and multidisciplinary factors that underlie individual activity-travel patterns in a developing country. Preliminary analyses of the collected data indicate that different beliefs, anticipated emotions, support and attachment to motorised modes significantly correlate with different groups of occupation, gender, age, activity participation, multi-tasking activities, and physical health, but not with different social and mental health. This finding highlights the reason why implementing car reduction policies in Indonesia, without breaking or changing the individual's habits and influencing his/her attitudes have not been fruitful. The results also show that endorsing more physical activities may result in a significant reduction in the individual's motorised mode use, whilst individuals who demonstrate a tendency to use their spare time on social activities tend to have better social health conditions. Furthermore, undertaking multi-tasking out-of-home discretionary activities positively correlates with better physical health. All these highlight the importance of properly understanding and analysing the complex mechanisms that underlie these fundamental factors that shape individual daily activity-travel patterns in developing countries. This type of multidisciplinary approach is needed to design better transport policies that will not only promote better transport conditions, but also a healthier society with a better quality of life.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Bandung Metropolitan Area (Indonesia), Health, Long term survey, Psychological factors, Time use and activity diary, Travel behaviour, Developing countries, Motor transportation, Multitasking, Transportation, Activity-travel patterns, Daily activity-travel patterns, Health-related quality of lives, Indonesia, Multi-disciplinary approach, Time use, developing world, household structure, metropolitan area, psychology, quality of life, transportation policy, travel behavior, urban transport, Bandung, West Java
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-176231 (URN)10.1016/j.tra.2015.08.001 (DOI)000362607200016 ()2-s2.0-84940644787 (Scopus ID)
Note

QC 20151116

Available from: 2015-11-16 Created: 2015-11-02 Last updated: 2017-12-01Bibliographically approved
Liu, C., Susilo, Y. O. & Karlstrom, A. (2015). Investigating the impacts of weather variability on individual's daily activity-travel patterns: A comparison between commuters and non-commuters in Sweden. Transportation Research Part A: Policy and Practice, 82, 47-64
Open this publication in new window or tab >>Investigating the impacts of weather variability on individual's daily activity-travel patterns: A comparison between commuters and non-commuters in Sweden
2015 (English)In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 82, p. 47-64Article in journal (Refereed) Published
Abstract [en]

Understanding travel behaviour change under various weather conditions can help analysts and policy makers incorporate the uniqueness of local weather and climate within their policy design, especially given the fact that future climate and weather will become more unpredictable and adverse. Using datasets from the Swedish National Travel Survey and the Swedish Meteorological and Hydrological Institute that spans a period of thirteen years, this study explores the impacts of weather variability on individual activity-travel patterns. In doing so, this study uses an alternative representation of weather from that of directly applying observed weather parameters. Furthermore, this study employs a holistic model structure. The model structure is able to analyse the simultaneous effects of weather on a wide range of interrelated travel behavioural aspects, which has not been investigated in previous weather studies. Structural equation models (SEM) are applied for this purpose. The models for commuters and non-commuters are constructed separately. The analysis results show that the effects of weather can be even more extreme when considering indirect effects from other travel behaviour indicators involved in the decision-making processes. Commuters are shown to be much less sensitive to weather changes than non-commuters. Variation of monthly average temperature is shown to play a more important role in influencing individual travel behaviour than variation of daily temperature relative to its monthly mean, whilst in the short term, individual activity-travel choices are shown to be more sensitive to the daily variation of the relative humidity and wind speed relative to the month mean. Poor visibility and heavy rain are shown to strongly discourage the intention to travel, leading to a reduction in non-work activity duration, travel time and the number of trips on the given day. These findings depict a more comprehensive picture of weather impact compared to previous studies and highlight the importance of considering interdependencies of activity travel indicators when evaluating weather impacts.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Weather variability, Activity-travel patterns, Long term and short term impacts, Structural equation model, Commuters and non-commuters, Sweden
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-180625 (URN)10.1016/j.tra.2015.09.005 (DOI)000366777200004 ()2-s2.0-84942305121 (Scopus ID)
Note

QC 20160120

Available from: 2016-01-20 Created: 2016-01-19 Last updated: 2017-11-30Bibliographically approved
Chengxi, L., Susilo, Y. O. & Karlström, A. (2015). Jointly modelling individual’s daily activity-travel time use andmode share by a nested multivariate Tobit model system. In: Transportation Research Procedia: 21st International Symposium on Transportation and Traffic Theory. Paper presented at 21st International Symposium on Transportation and Traffic Theory,5 - 7 August, 2015, Kobe, Japan (pp. 71-89). Elsevier, 9
Open this publication in new window or tab >>Jointly modelling individual’s daily activity-travel time use andmode share by a nested multivariate Tobit model system
2015 (English)In: Transportation Research Procedia: 21st International Symposium on Transportation and Traffic Theory, Elsevier, 2015, Vol. 9, p. 71-89Conference paper, Published paper (Refereed)
Abstract [en]

Understanding mechanisms underlie the individual’s daily time allocations is very important to understand the variability ofindividual’s time-space constraints and to forecast his/her daily activity participation. At most of previous studies, activity timeallocation was viewed as allocating a continuous quantity (daily time budget) into multiple discrete alternatives (i.e. variousactivities and trips to engage with). However, few researches considered the influence of travel time that needs to be spent onreaching the activity location. Moreover, travel time itself is influenced by individuals’ mode choice. This can lead to an over- orunder-estimation of particular activity time location. In order to explicitly include the individual’s travel time and mode choiceconsiderations in activity time allocation modelling, in this study, a nested multivariate Tobit model is proposed. This proposedmodel can handle: 1. Corner solution problem (i.e. the present of substantial amount of zero observations); 2. Time allocationtrade-offs among different types of activities (which tends to be ignored in previous studies); 3. Travel is treated as a deriveddemand of activity participation (i.e. travel time and mode share are automatically censored, and are not estimated, ifcorresponding activity duration is censored). The model is applied on a combined dataset of Swedish national travel survey(NTS) and SMHI (Swedish Meteorological and Hydrological Institute) weather record. Individuals’ work and non-work activitydurations, travel time and mode shares are jointly modelled as dependent variables. The influences of time-locationcharacteristics, individual and household socio demographics and weather characteristics on each dependent variable areexamined. The estimation results show a strong work and non-work activity time trade-offs due to the individual’s time-spaceconstraints. Evidences on a potential positive utility of travel time added on non-work activity time allocation in the Swedish case,are also found. Meanwhile, the results also show a consistent mode choice preference for a given individual. The estimatednested multivariate Tobit model provides a superior prediction, in terms of the deviation of the predicted value against the actualvalue conditional on the correct prediction regarding censored and non-censored, compared to mutually independent Tobitmodels. However, the nested multivariate Tobit model does not necessarily have a better prediction for model componentsregarding non-work related activities.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
multiple discrete-continuous model, sample selection model, activity-travel time allocation
National Category
Transport Systems and Logistics
Research subject
Transport Science; Transport Science; Transport Science
Identifiers
urn:nbn:se:kth:diva-187017 (URN)10.1016/j.trpro.2015.07.005 (DOI)000380485800015 ()2-s2.0-84959347867 (Scopus ID)
Conference
21st International Symposium on Transportation and Traffic Theory,5 - 7 August, 2015, Kobe, Japan
Note

QC 20160517

Available from: 2016-05-16 Created: 2016-05-16 Last updated: 2019-09-20Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5290-6101

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