| 1. |
- Almström, Peter, et al.
(författare)
-
Modelling the effect of transit supply and price structure on mode choice and route choice
- 2011
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Konferensbidrag (refereegranskat)abstract
- This paper develops a new mode choice and transit route choice model for work trips by either car or transit. In contrast to the conventional regional traffic models used for transportation planning in Sweden, the model accounts for the fact that the value of time varies within a population of travellers making a trip with the same purpose and the fact that the price can differ between different transit lines (bus, regional trains, etc.). A mixed binomial logit (MXL) model with a lognormally distributed cost parameter has been estimated for the mode choice. The MXL specification makes it possible to capture some of the variation in the value of time. The transit route choice model rests on the assumption that transit commuters purchase travel passes that are valid for a certain time period, e.g. a month. The travel pass then allows the traveller to use a certain set of transit lines, while others are not available. For the mode choice, the traveller compares travel cost and time with the chosen pass with the travel cost and time by car. The results from performed analyses indicate that if the interest is in overall mode share and overall travel flows, the conventional method in Swedish transport modelling will suffice. However, if the interest is more detailed, for example concerning boardings and ticket income from a certain transit line, or the total benefit of a price change, the model developed in this paper will give more reliable results.
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| 2. |
- Andersson, Angelica, et al.
(författare)
-
Long-distance mode choice model estimation using mobile phone network data
- 2022
-
Ingår i: Journal of Choice Modelling. - : Elsevier. - 1755-5345. ; 42
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we develop two methods for the use of mobile phone data to support the estimation of long-distance mode choice models. Both methods are based on logit formulations in which we define likelihood functions and use maximum likelihood estimation. Mobile phone data consists of information about a sequence of antennae that have detected each phone, so the mode choice is not actually observed. In the first trip-based method, the mode of each trip is inferred by a separate procedure, and the estimation process is then straightforward. However, since it is not always possible to determine the mode choice with certainty (although it is possible in the majority of cases), this method might give biased results. In our second antenna-based method we therefore base the likelihood function on the sequences of antennae that have detected the phones. The estimation aims at finding a parameter vector in the mode choice model that would explain the observed sequences best. The main challenge with the antenna-based method is the need for detailed resolution of the available data. In this paper we show the derivation of the two methods, that they coincide in case of certainty about the chosen mode and discuss the validity of assumptions and their advantages and disadvantages. Furthermore, we apply the first trip-based method to empirical data and compare the results of two different ways of implementing it.
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| 3. |
- Andersson, Angelica, et al.
(författare)
-
Long-distance mode choice model estimation using mobile phone network data
- 2022
-
Ingår i: Journal of Choice Modelling. - : Elsevier. - 1755-5345. ; 42
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we develop two methods for the use of mobile phone data to support the estimation of long-distance mode choice models. Both methods are based on logit formulations in which we define likelihood functions and use maximum likelihood estimation. Mobile phone data consists of information about a sequence of antennae that have detected each phone, so the mode choice is not actually observed. In the first trip-based method, the mode of each trip is inferred by a separate procedure, and the estimation process is then straightforward. However, since it is not always possible to determine the mode choice with certainty (although it is possible in the majority of cases), this method might give biased results. In our second antenna-based method we therefore base the likelihood function on the sequences of antennae that have detected the phones. The estimation aims at finding a parameter vector in the mode choice model that would explain the observed sequences best. The main challenge with the antenna-based method is the need for detailed resolution of the available data. In this paper we show the derivation of the two methods, that they coincide in case of certainty about the chosen mode and discuss the validity of assumptions and their advantages and disadvantages. Furthermore, we apply the first trip-based method to empirical data and compare the results of two different ways of implementing it.
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| 4. |
- Andersson, Angelica, et al.
(författare)
-
Mode Choice Latent Class Estimation on Mobile Network Data
- 2024
-
Ingår i: SSRN Electronic Journal. - : Elsevier BV. - 1556-5068.
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we use a nested latent class logit specification to define and estimate a large-scale mode choice demand forecasting model. We estimate this model based on mobile phone network data translated to roughly 100 000 long-distance trips within Sweden, achieving convergence of the model and credible parameter estimates. We develop methods to address two problems stemming from the nature of this data: the difficulties of distinguishing bus trips from car trips (since they share the same infrastructure) and distinguishing business from private trips (since trip purpose is unknown). To address the first issue, we estimate a nested logit model with an artificial nest that accounts for the differences in utility between bus and car. To address the latter issue, we estimate a latent class model, identifying classes of trips interpreted as private and business trips. Addressing these two issues substantially improves model fit.
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| 5. |
- Andersson, Angelica
(författare)
-
Mode choice modelling of long-distance passenger transport based on mobile phone network data
- 2022
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Reliable forecasting models are needed to achieve the climate related goals in the face of increasing transport demand. Such models can predict the long-term behavioural response to policy interventions, including infrastructure investments, and thus provide valuable pre-dictions for decision makers. Contemporary forecasting models are mainly based on national travel surveys. Unfortunately, the response rates of such surveys have steadily declined, implying that the respondents become less representative of the whole population. A particular weakness is that it is likely that respondents with a high valuation of time are less willing to respond to surveys (because they have less time available for such), and therefore there is a high chance that they are underrepresented among the respondents. The valuation of time plays an important role for the cost benefit analyses of public policies including transport investments, and there is no reliable way of controlling for this uneven sampling of time preferences. Fortunately, there is simultaneously an increase in the number of signals sent between mobile phones and network antennae, and research has now reached the point where it is possible to determine not only the travel destination but also the travel mode based on mobile phone network antennae connections. The aim of this thesis is to investigate if and how mobile phone network data can be used to estimate transportation mode choice demand models that can be used for forecasting and planning. Key challenges with using this data source in the context of mode choice models are identified and met. The identified challenges include uncertainty in the choice variable, the difficulty to distinguish car and bus trips, and the lack of information about the trip purpose. In the first paper we propose three possible model formulations and analyse how the uncertainty in the choice outcome variable would play a role in the different model formulations. We also conclude that it is indeed possible to estimate mode choice demand models based on mobile phone network data, with good results in terms of behavioural interpretability and significance. In the second paper we estimate models using a nested logit structure to account for the difficulty in separating bus and car, and a latent class model specification to meet the challenge of having an unknown trip purpose.
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| 6. |
- Andersson, Angelica, 1990-
(författare)
-
Modelling long-distance travel demand by combining mobile phone and survey data
- 2024
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Forecasts of the demand for long-distance travel are a key component enabling the calculation of social costs and benefits of policy actions such as infrastructure investments. Traditionally, such forecasting models have been based on travel survey data. However, response rates to travel surveys have been in decline for decades, calling into question whether the sample of respondents is really representative of the full population. As such, there is a need to explore alternative data sources. One promising alternative is mobile phone network data, which is collected without the need of active participation from the traveller. However, mobile phone network data in this thesis lacks trip and traveller specific information such as trip purpose, socio-economic information, travel party size and mode. Furthermore, it is difficult to distinguish between bus and car trips even at a later stage of data processing, as the two modes share the same infrastructure. The objective of this thesis is to investigate the use of mobile phone network data for long-distance mode choice modelling. More specifically, we investigate the specific aspects of mobile phone network data as a source of mode choice travel information in the first research paper of this thesis, how uncertainties connected to the identification of the used mode matter, and how it can be handled in the model. In the second research paper of this thesis, a full-scale Multinomial Logit mode choice model is implemented and evaluated, including the development of how to handle mobile phone network data-specific challenges in the dataset of this thesis, such as the lack of distinction between bus and car trips and the lack of trip purpose information. Once this full-scale mode choice model based only on mobile phone network data has been evaluated, a method for combining mobile phone network data with survey data is proposed in the third research paper of this thesis, and the joint model is compared to the mobile phone network data model in terms of behavioural credibility. Finally, it is investigated whether machine learning can be useful in modelling mode choices using the two data sources in the fourth research paper of this thesis. From the results of the papers included in this thesis, it is clear that it is possible to model mode choice based only on mobile phone network data, but that it is preferable to combine mobile phone network data with survey data, rather than to use any one data source separately. Either Multinomial Logit (MNL) models or Artificial Neural Networks (ANNs) can be used to model mode choices based on the two data sources. However, if ANN is selected for mode choice modelling, it is advisable to formulate the network based on the transport mode choice specific principles developed in the last paper of this thesis.
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| 7. |
- Canella, Olivier, et al.
(författare)
-
Fördelningsanalys med Sampers 4
- 2024
-
Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 88-89
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Sampers 4, utvecklad av Trafikverket, kommer vara den officiella versionen från och med april 2024 och kommer användas för kommande åtgärdsplanering. Modellen är implementerad i Emme och simulerar individuellt resebeteende för hela Sveriges befolkning (utifrån en skapad syntetisk befolkning). Sampers 4 har fem regionala modeller med totalt 11 000 zoner. Antalet hembaserade ärenden är tolv, dessutom finns ett arbetsbaserat ärende. Modellimplementeringen hanterar flera specifika krav.För varje agent och ärende beräknas konsumentöverskott som skillnad mellan logsummor i UA och JA. Vilka logsummor som tas med beror på ärendet: för de ärenden där resefrekvensen beror på tillgänglighet (t ex. rekreationsresor) används logsumman från valet att resa/inte resa, medan för ärenden som sker oberoende av tillgängligheten (t ex skolresor) ingår logsumman från färdmedels- och destinationsvalet. Konsumentöverskottet omvandlas till tid m h a logsummeparametrar och restidsparametrar för respektive ärende. Restidsparametern blir gemensam för alla agenter och bestäms utifrån investeringens typ: kollektivtrafik eller bil. Omvandling från tid till pengar sker enligt tidsvärden i ASEK-rapporten. Slutligen delas summa konsumentöverskott över alla ärenden och agenter i varje socioekonomisk grupp med antalet agenter i gruppen. Genom att jämföra den genomsnittliga vinsten över kategorier (kön / ålder / inkomst / boendeform / kommun) kan man analysera vilka grupper som vinner mest och minst på åtgärden.Den här metoden kräver att man fryser bil-, körkorts- och periodkortsinnehav i efterfrågemodell. Det innebär att anpassningskostnader i samband med anskaffande av bil, körkort eller periodkort inte ingår i analysen. Metoden är implementerat i en Emme Modeller tool (python skript).Från verktygen skapas en excel rapport med fördelning av konsumentöverskottet enligt olika fördefinierade kategorier (t.ex. Kön / Ålder / Inkomst / Boendeform). Resultatet av en fördelningsanalys för ett järnvägsobjekt kommer att visas i presentationen. Sampers 4, implementerat som en agent-baserat modell, ger möjlighet till en kvantitativ fördelningsanalys för många socio-ekonomiska dimensioner. Det kommer att bidra till ett bättre underlag vid åtgärdsplanering.
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| 8. |
- Canella, Olivier, et al.
(författare)
-
Mikrosimuleringsvariabilitet i en agentbaserad resemodell (Sampers) för sverige
- 2024
-
Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 93-94
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Sampers 4, utvecklad av Trafikverket, kommer vara den officiella versionen från och med april 2024. Modellen är implementerad i Emme och simulerar individuellt resebeteende för hela Sveriges befolkning (utifrån en skapad syntetisk befolkning). Sampers 4 har fem regionala modeller med totalt 11 000 zoner. Antalet hembaserade ärenden är tolv, dessutom finns ett arbetsbaserat ärende. En modell för bilinnehav och periodkort för kollektivtrafik är inkluderad i de fem regionala modellerna. Modellimplementeringen hanterar flera specifika krav såsom:Stöd för olika regionala tillämpningar (utförda av flera myndigheter och modellanvändare över hela landet) där endast en region ska simuleras med hög detaljnivå medan resten av landet kan simuleras mer aggregerat. Stöd för rådande samhällsekonomiska analys vilket realiseras genom en ny version av Samkalk.Inbyggd variabilitet i mikrosimulering på grund av användningen av slumpmässiga tal har alltid varit en av de främsta utmaningarna för praktiska tillämpningar. För att initialisera genereringen av slumpmässiga variabler i efterfrågemodeller används ett så kallat slumpfrö, ett tal som väljs av en analytiker eller modellutvecklare. Valet av slumpfrö bestämmer den specifika sekvensen av slumpmässiga tal som genereras, vilket i sin tur påverkar resultatet av simuleringen. Om samma slumpfrö används i flera körningar kommer samma sekvens av slumpmässiga nummer att genereras, vilket resulterar i samma modellutdata. Om olika slumpfrön används kommer olika sekvenser av slumpmässiga nummer att genereras, vilket leder till olika modellutdata.Vi utvärderade effekten av frövärdet dels på beräknad prognos med Sampers 4 (bil- och periodkortinnehav, resegenerering, färdmedelsval), dels på beräknad nytta (med Samkalk) för två objekt: en stor väginvestering i ett hårt trafikerat område (Tvärförbindelse Södertörn) samt ett järnvägsprojekt (Norrbotniabanan) för prognosåret 2040 genom att utföra flera körningar. Både jämförelsealternativ (JA) och utredningsalternativ (UA) kördes med samma slumpfrö vilket innebär att individuella värderingar antas vara samma i båda situationerna, även om de individuella valen kan vara olika. Resultaten visar att transportefterfrågemodell (bil- och periodkortinnehav, resegenerering, färdmedelsval) och samhällsekonomisk analys är stabila med avseende på slumpfrö. Till exempel är standardavvikelsen för totala nyttan av Tvärförbindelse Södertörn cirka 1.3% av medelvärdet och nyttan varierar inom ett intervall av 3.2% beroende på värdet för slumpfröet (analys med 6 olika slumpfrön).
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| 9. |
- de Palma, André, et al.
(författare)
-
Network market conduct with atomic and non-atomic players
- 2012
-
Konferensbidrag (refereegranskat)abstract
- In a non-atomic network game, there is a continuum of selfish users, independently choosing routes from the origins to thedestinations of their trips. In the static version of the game, each link of the network is endowed by a continuous increasing costfunction of the total flow of agents on the link. It is well known that a Nash equilibrium when no user can decrease own route costby unilaterally changing their route exists and is generally less efficient than the system optimum. In the last decade, a considerableamount of literature was devoted to designing Stackelberg routing in order to reduce the cost of anarchy, i.e. the ratio between thetotal cost of Nash and the system optimum cost, see e.g. Harks (2011) for overview. Apart from the non-atomic users theStackelberg routing assumes an atomic player - a leader - that can unilaterally and consciously influence the cost for thenon-atomic users – the followers - by partially controlling their route choice for a fraction of users. It is usually assumed that thecontrolled users perceive the same cost on each link as the uncontrolled ones.In our paper, we assume that there are two types of agents, which have different cost functions. As an example of such situation,one could consider a continuum of cars and a fleet of trucks. Indeed, the truck speed is normally lower than that of the cars and isless influenced by the congestion. Moreover, the truck route choice may be controlled by a common agency that pursues a strategyof minimising the total cost forof truck (private agency) or the total cost for all vehicles (governmental agency). The costs of usingthe routes areis route specific and vehicle type specific and isare given as specified as a linear functions of the total number ofusers on the route. Each car is atomic and ignores the impact of his decision on congestion. On the contrary, the coordinator of thefleet may take into account the total congestion cost of the trucks and of the cars. We consider several market situations:Stackelberg equilibrium with trucks controlled by the private agency(Stackelberg), the social system optimum, the second-bestoptimum with trucks controlled by the governmental agency, as well as the benchmark (Nash) with no coordination at all. Despitethe simple formulation, all scenarios beside the Nash lead to non-convex minimisation problems. Each of these problems alwayshas a non-interior solution although interior solutions may exist too.Without the coordination, the trucks and the cars choose their routes according to the deterministic user equilibrium. In the socialoptimum, the total cost for cars and trucks is minimised, and it is almost always possible to obtain a non-interior solution withlower total cost than in the user equilibrium.In the network consisting of two identical (i.e. with similar cost functions) parallel routes the trucks cannot benefit from thecoordination and the Stackelberg equilibrium coincides with Nash equilibrium. However, if there are more trucks (car equivalents)than cars and if the car cost function is steeper than the truck cost function, then the governmental agency can improve the socialwelfare compared to the user equilibrium scenario. In this case, moving a truck from the route that accumulates all cars increasethe total cost for trucks but decreases the total cost for the whole collection of vehicles.If the two routes are not identical then the coordination of trucks may actually worsen the situation by reducing the cost for trucksbut increasing the cost for cars and the total cost compared to the Nash equilibrium. On the other side, the governmental agencycontrolling the trucks may decrease the total cost to a value which is lower than the total cost in the Nash equilibrium at the sametime increasing the cost for trucks.In the Stackelberg game, the fleet of trucks is coordinated in order to minimise their total cost. We show that there is always anon-interior solution. However, in the case of identical routes neither cars nor trucks benefit from the coordination of the truck fleetsince equilibrium and optimum coincides. SAY WHAT COULD HAPPEN IN A NON SYMETRIC Finally, in the second bestscenario we envisage, we assume that the trucks choose routes so that the total cost over all vehicles (cars and trucks) is minimised.In the symmetric case, but with different cost functions for trucks and for cars, we have shown that no benefit can be obtained bythe coordination if the number of cars exceeds the number of trucks. However, with more trucks than cars, there is always apossibility to improve the social welfare compared to the user equilibrium scenario. PROVIDE SOME HINT WHY HEREWe finally examine the coordination game, when two fleets of trucks are competingcompeting for what. And the so what?Add the reference that I asked you to add.
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| 10. |
- Ekström, J., et al.
(författare)
-
A heuristic method for finding congestion pricing schemes in traffic networks with modal choice
- 2008
-
Ingår i: Proceedings of the 13th International Conference of Hong Kong Society for Transportation Studies. - 9789889884734 ; , s. 773-782
-
Konferensbidrag (refereegranskat)abstract
- In this paper we extend a previously developed heuristic procedure, with a modal choice model, to solve the congestion pricing problem of simultaneously finding the optimal number of toll facilities, their corresponding location and toll levels. When considering a congestion pricing scheme the cost of collecting the tolls can not be disregarded. The objective is wherefore to maximize the net social surplus, which is the social surplus minus the cost of collecting the tolls. The heuristic method is an iterative solution procedure, in which the integer part of the objective function is approximated by a continuous function. A version of the Sioux Falls network (76 links) is used to demonstrate the solution procedure. The solution is a congestion pricing scheme which divide the network into four zones, by locating tolls on 27 links. This solution yields a social surplus which is only 13.5% lower than the marginal social cost pricing solution.
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| 11. |
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| 12. |
- Ekström, Joakim, 1980-, et al.
(författare)
-
A heuristic method for finding congestion pricing schemes in transportation networks with modal choice
- 2008
-
Ingår i: International conference of Hong Kong society for transportation studies,2008. - Hong Kong, China : Hong Kong Society of Transportation Studies Ltd.. - 9789889884734 ; , s. 773-782
-
Konferensbidrag (refereegranskat)abstract
- In this paper we extend a previously developed heuristic procedure, with a modal choice model, to solve the congestion pricing problem of simultaneously finding the optimal number of toll facilities, their corresponding location and toll levels. When considering a congestion pricing scheme the cost of collecting the tolls can not be disregarded. The objective is where-fore to maximize the net social surplus, which is the social surplus minus the cost of collect-ing the tolls. The heuristic method is an iterative solution procedure, in which the integer part of the objec-tive function is approximated by a continuous function. A version of the Sioux Falls network (76 links) is used to demonstrate the solution procedure. The solution is a congestion pricing scheme which divide the network into four zones, by locating tolls on 27 links. This solution yields a social surplus which is only 13.5% lower than the marginal social cost pricing solu-tion.
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| 13. |
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| 14. |
- Ekström, Joakim, 1980-, et al.
(författare)
-
Decision support for finding locations and toll levels within a congestion pricing scheme
- 2008
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Ingår i: Transportation Research Board Annual Meeting,2008. - Washington D.C. : TRB.
-
Konferensbidrag (refereegranskat)abstract
- Designing a congestion pricing scheme involves a number of complex decisions. Focusing on the quantitative parts of a congestion pricing system with link tolls, the problem involves finding the number of tolled links, the link toll locations and their corresponding toll level and schedule. In this paper, we develop and evaluate methods for finding a most efficient design of a congestion pricing scheme in a road network with elastic demand. The design efficiency is measured by the net social surplus, which is computed as the difference between the social surplus and the collection costs (i.e. setup and operation cost) of the congestion pricing system. The problem of finding such a scheme is stated as a combinatorial bi-level optimization problem. On the upper level we maximize the net social surplus and on the lower level we solve a user equilibrium problem with elastic demand, given the toll locations and toll levels, to simulate the user response. We modify a known heuristic procedure for finding the optimal locations and toll levels given a fixed number of tolls to locate, to find the optimal number of tolls to locate as well. A new heuristic procedure is also presented which is based on repeated solutions of a continuous approximation of the combinatorial problem. Numerical results for two small scale test networks are presented. Both methods perform satisfactory on the two networks. Comparing the two methods, the iterative approximation procedure is the one which shows the best results. The results are compared to solutions obtained by an exhaustive search.
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| 15. |
- Ekström, Joakim, 1980-, et al.
(författare)
-
Heuristic algorithms for a second-best congestion pricing problem
- 2009
-
Ingår i: Netnomics. - : Springer Science and Business Media LLC. - 1385-9587 .- 1573-7071. ; 10:1, s. 85-102
-
Tidskriftsartikel (refereegranskat)abstract
- Designing a congestion pricing scheme involves a number of complex decisions.Focusing on the quantitative parts of a congestion pricing system with link tolls, the problem involves findingthe number of toll links, the link toll locations and their corresponding toll level and schedule.In this paper, we develop and evaluate methods for finding the most efficient design for a congestion pricing scheme in a road network model with elastic demand. The design efficiency is measured by the net social surplus, which is computed as the difference between the social surplus and the collection costs (i.e. setup and operational costs) of the congestion pricing system. The problem of finding such a scheme is stated as a combinatorial bi-level optimization problem. At the upper level, we maximize the net social surplus and at the lower level we solve a user equilibrium problem with elastic demand, given the toll locations and toll levels,to simulate the user response. We modify a known heuristic procedure for finding the optimal locations and toll levels given a fixed number of tolls to locate, to find the optimal number of toll facilities as well. A new heuristic procedure, based on repeated solutions of a continuous approximation of the combinatorial problem is also presented. Numerical results for two small test networks are presented. Both methods perform satisfactorily on the two networks. Comparing the two methods, we find that the continuous approximation procedure is the one which shows the best results.
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| 16. |
- Ekström, Joakim, et al.
(författare)
-
Optimal Toll Locations and Levels in Congestion Pricing Schemes : a Case Study of Stockholm
- 2014
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Ingår i: Transportation planning and technology (Print). - : Routledge. - 0308-1060 .- 1029-0354. ; 37:4, s. 333-353
-
Tidskriftsartikel (refereegranskat)abstract
- As congestion pricing has moved from theoretical ideas in the literature to real world implementations, the need for decision support when designing the pricing schemes has become evident. This paper deals with the problem of finding optimal toll levels and locations in a road traffic network, and presents a case study of Stockholm. The optimization problem of finding optimal toll levels, given a predetermined cordon, and the problem of finding both optimal toll locations and levels are presented, and previously developed heuristics are used for solving these problems. For the Stockholm case study, the possible welfare gains of optimizing the toll levels in the current cordon, and optimizing both the toll locations and their corresponding toll levels are evaluated. It is shownthat by tuning the toll levels in the current congestion pricing cordon used in Stockholm, the welfare gain can be significantly increased, and furthermore improved by allowing a toll on the bypass highway “Essingeleden”. It is also shown that by optimizing both the toll locations and levels, a congestion pricing scheme with welfare gain close to what can be achieved by marginal social cost pricing, can be designed with tolls being located on only a forth of the tollable links.
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| 17. |
- Ekström, Joakim, et al.
(författare)
-
Optimal toll locations and toll levels in congestion pricing schemes : a case study of Stockholm
- 2014
-
Ingår i: Transportation planning and technology (Print). - : Informa UK Limited. - 0308-1060 .- 1029-0354. ; 37:4, s. 333-353
-
Tidskriftsartikel (refereegranskat)abstract
- As congestion pricing has moved from theoretical ideas in the literature to real-world implementation, the need for decision support when designing pricing schemes has become evident. This paper deals with the problem of finding optimal toll levels and locations in a road traffic network and presents a case study of Stockholm. The optimisation problem of finding optimal toll levels, given a predetermined cordon, and the problem of finding both optimal toll locations and levels are presented, and previously developed heuristics are used for solving these problems. For the Stockholm case study, the possible welfare gains of optimising toll levels in the current cordon and optimising both toll locations and their corresponding toll levels are evaluated. It is shown that by tuning the toll levels in the current congestion pricing cordon used in Stockholm, the welfare gain can be increased significantly, and furthermore improved by allowing a toll on a major bypass highway. It is also shown that, by optimising both toll locations and levels, a congestion pricing scheme with welfare gain close to what can be achieved by marginal social cost pricing can be designed with tolls being located on only a quarter of the tollable links.
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| 18. |
- Ekström, Joakim, 1980-, et al.
(författare)
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Towards optimal locations and toll levels in congestion pricing schemes
- 2009
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Ingår i: 16th ITS World Congress. - : World Congress on Intelligent Transport Systems (ITS).
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses the problem of designing a road congestion pricing scheme with link tolls. The problem involves decisions on where to locate the toll collecting facilities and what tolls to charge the road users. We formulate this problem as a bi-level program, with the objective to maximize the net social surplus, which include the cost of setting up and operate the toll collection system. A previously developed heuristic method is applied to find close to optimal toll locations and charges for a traffic network representing the Stockholm region. The result is compared with the current congestion pricing scheme in Stockholm.
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| 19. |
- Eliasson, Jonas, et al.
(författare)
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Accuracy of congestion pricing forecasts
- 2013
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Ingår i: Transportation Research Part A. - : Elsevier BV. - 0965-8564 .- 1879-2375. ; 52, s. 34-46
-
Tidskriftsartikel (refereegranskat)abstract
- This paper compares forecast effects of the Stockholm congestion charges with actual outcomes. The most important concerns during the design of the congestion charging scheme were the traffic reduction in bottlenecks, the increase in public transport ridership, the decrease of vehicle kilometres in the city centre, and potential traffic effects on circumferential roads. Comparisons of forecasts and actual outcomes show that the transport model predicted all of these factors well enough to allow planners to draw correct conclusions regarding the design and preparations for the scheme. The one major shortcoming was that the static assignment network model was unable to predict the substantial reductions of queuing times. We conclude that the transport model worked well enough to be useful as decision support, performing considerably better than unaided "experts' judgments", but that results must be interpreted taking the model's limitations into account. The positive experiences from the Stockholm congestion charges hence seem to be transferable to other cities in the sense that if a charging system is forecast to have beneficial effects on congestion, then this is most likely true.
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| 20. |
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| 21. |
- Engelson, Leonid, et al.
(författare)
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Additive measures of travel time variability
- 2011
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Ingår i: Transportation Research Part B. - : Elsevier BV. - 0191-2615 .- 1879-2367. ; 45:10, s. 1560-1571
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Tidskriftsartikel (refereegranskat)abstract
- This paper derives a measure of travel time variability for travellers equipped with scheduling preferences defined in terms of time-varying utility rates, and who choose departure time optimally. The corresponding value of travel time variability is a constant that depends only on preference parameters. The measure is unique in being additive with respect to independent parts of a trip. It has the variance of travel time as a special case. Extension is provided to the case of travellers who use a scheduled service with fixed headway.
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| 22. |
- Engelson, Leonid, et al.
(författare)
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Comparison of two dynamic transportation models : The case of Stockholm congestion charging
- 2012
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Konferensbidrag (refereegranskat)abstract
- This paper reviews the transportation models used for predicting impacts of congestion charging in European cities and carries out in-depth comparison of two such models, METROPOLIS and SILVESTER. Both are mesoscopic dynamic models involving modal split and departure time choice calibrated for the Stockholm baseline situation without charges and applied for modeling effects of congestion charging. The results obtained from the two models are mutually compared and validated against actual outcome of the Stockholm congestion charging scheme. Both models provide significant improvement in realism over static models. However results of cost benefit analysis differ substantially
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| 23. |
- Engelson, Leonid, et al.
(författare)
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Congestion Pricing of Road Networks with Users Having Different Time Values
- 2006
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Ingår i: Mathematical and Computational Models for Congestion Charging. - : Springer Science+Business Media B.V.. ; , s. 81-104
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Bokkapitel (refereegranskat)abstract
- We study congestion pricing of road networks with users differing onlyin their time values. In particular, we analyze the marginal social cost (MSC) pricing,a tolling scheme that charges each user a penalty corresponding to the value of thedelays inflicted on other users, as well as its implementation through fixed tolls. Weshow that the variational inequalities characterizing the corresponding equilibria canbe stated in symmetric or nonsymmetric forms. The symmetric forms correspondto optimization problems, convex in the fixed-toll case and nonconvex in the MSCcase, which hence may have multiple equilibria. The objective of the latter problemis the total value of travel time, which thus is minimized at the global optima of thatproblem. Implementing close-to-optimal MSC tolls as fixed tolls leads to equilibriawith possibly non-unique class specific flows, but with identical close-to-optimalvalues of the total value of travel time. Finally we give an adaptation, to the MSCsetting, of the Frank-Wolfe algorithm, which is further applied to some test cases,including Stockholm.
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| 24. |
- Engelson, Leonid, et al.
(författare)
-
Convexification of the Traffic Equilibrium Problem with Social Marginal Cost Tolls
- 2004
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Ingår i: Operations Research Proceedings 2003. - Berlin, Heidelberg : Springer Berlin/Heidelberg. ; , s. 141-148
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In an earlier paper, we have demonstrated that traffic equilibria under social marginal cost tolls can be computedas a local optima of a nonconvex optimization problem. The nonconvexity of this problem implies in particular that linearizations, e.g. the Frank-Wolfe method, do not give underestimates of the optimal value. In this paper we derive the convex hull of nonconvex arc cost functions of BPR type. These convexifications can be used to get underestimates of the optimal value, or get better search directions in the initial phase of the Frank-Wolfe method. Computational results for the Sioux Falls and Stockholm networks are reported.
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| 25. |
- Engelson, Leonid
(författare)
-
EXISTENCE OF TOLL EQUILIBRIUM IN TRAFFIC NETWORK WITH DRIVERS HAVING DIFFERENT TIME VALUES
- 2006
-
Ingår i: PRO CEED INGS OF THE LAT VIAN ACAD EMY OF SCI ENCES. Sec tion B. - Riga : THE LATVIAN ACADEMY OF SCIENCES. - 1407-009X. ; 60:2/3, s. 55-57
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, the purpose of traffic management is formulated as a set of constraints imposed on traffic flows along some links in the road network. The discussed problem is: what charges should be inflicted to the drivers on the links so that the traffic volumes on these links satisfy certain upper bounds. While well investigated in the situation when all drivers have the same time value, the problem with drivers having different time values, although more realistic, has not received much attention. The paper presents a proof that a solution to this problem exists under a natural condition that the whole travel demand can be served by the road network within the imposed constraints.
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| 26. |
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| 27. |
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| 28. |
- Engelson, Leonid, et al.
(författare)
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Multi-Class User Equilibria under Social Marginal Cost Pricing
- 2002
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Ingår i: Operations Research 2002. - 9783540003878 ; , s. 174-179
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the congested cities of today, congestion pricing is a tempting alternative. With a single user class, already Beckmann et al. showed that ``system optimal'' traffic flows can be achieved by social marginal cost (SMC) pricing where users have to pay for the delays the incur on others. However different user classes can have widly differing time values. Hence, when introducing tolls, one should consider multi-class user equilibria, where the classes have different time values. In the single class case, the equilibrium conditions can be viewn as optimality conditions of an equivalent optimization problem. In the multi-class case, however, netter claims that this is not possible. We show that, depending on the formulation, the multi-class SMC-pricing equilibrium problem (with different time values) can be stated either as an asymmetric or as a symmetric equilibrium problem. In the latter case, the corresponding optimization problems is in general non-convex. For this non-convex problem, we devise descent methods of Frank-Wolfe type. We apply the methods and study a synthetic case based on Sioux Falls.
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| 29. |
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| 30. |
- Engelson, Leonid
(författare)
-
On dynamics of traffic queues in a road network with route choice based on real time traffic information
- 2003
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Ingår i: Transportation Research Part C. - : Elsevier BV. - 0968-090X .- 1879-2359. ; 11:2, s. 161-183
-
Tidskriftsartikel (refereegranskat)abstract
- Introducing real time traffic information into transportation network makes it necessary to consider development of queues and traffic flows as a dynamic process. This paper initiates a theoretical study of conditions under which this process is stable. A model is presented that describes within-one-day development of queues when drivers affected by real-time traffic information choose their paths en route. The model is reduced to a system of differential equations with delay. Equilibrium points of the system correspond to constant queue lengths. Stability of the system is investigated using characteristic values of the linearised minimal face flow. A traffic network example illustrating the method is provided.
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| 31. |
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| 32. |
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| 33. |
- Engelson, Leonid
(författare)
-
Properties of Expected Travel Cost Function with Uncertain Travel Time
- 2011
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2254, s. 151-159
-
Tidskriftsartikel (refereegranskat)abstract
- The paper presents a theoretical analysis of travelers' scheduling preferences and the resulting form of the expected utility that includes travel time reliability measures. A series of research papers and reports used the mean standard deviation approach to evaluate policies that improve travel time reliability. Recently, this approach was theoretically substantiated under the conventional assumptions of constant marginal utility of time (MUT) at the origin, two discrete MUT values at the destination, and constant standardized travel time distribution. In this paper, properties of the minimal expected travel cost are investigated with smooth MUTs at the origin and destination of the trip. The influence of small variations in travel time on travel cost is well approximated by a term proportional to the travel time variance and independent of the distribution form of travel time. Two examples of MUT functions are provided: the minimal expected travel cost can be analytically expressed through moments or through a moment generating function of travel time, and conditions are stated guaranteeing that the expected travel cost is exactly additive by independent parts of the trip. These results provide justification in particular for the mean variance approach to modeling drivers' decisions under uncertain travel times. This formulation is convenient especially for scheme evaluation in large road networks because it allows the use of conventional network assignment routines by just modifying the volume delay functions to include the travel time variability term.
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| 34. |
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| 35. |
- Engelson, Leonid, et al.
(författare)
-
Scheduling preferences and the value of travel time information
- 2020
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Ingår i: Transportation Research Part B. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0191-2615 .- 1879-2367. ; 134, s. 256-265
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we derive the value of a signal obtained by a traveller prior to the choice of departure time. The signal does not have to be a perfect prediction of the travel time. It is sufficient that it carries information about the travel time. The traveller may then consider the distribution of travel time conditional on the signal to increase her expected utility by making a better informed choice of departure time. We show that a signal always increases the expected utility compared to the situation without any signal. For a broad class of signals, the expected utility is monotone with respect to signal strength. Furthermore, we demonstrate that even perfect travel time information does not necessarily eliminate the cost of travel time variability and we establish necessary and sufficient conditions for when it does. We find that the predictable part of travel time variability may or may not be costly, depending on the shape of the traveller's scheduling utility at the origin of the trip. Using estimates of scheduling preferences from the literature, we show that the cost of predictable travel time variability may constitute a substantial part of the total cost of travel time variability. In a particular case of scheduling preferences, travel time distribution and noise distribution, we establish an analytic relationship between the strength of the signal and the expected utility of the trip and evaluate the marginal cost of signal weakness. This knowledge may facilitate design and cost-benefit analysis of traveller information systems and policies decreasing travel time variability. (C) 2020 Elsevier Ltd. All rights reserved.
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| 36. |
- Engelson, Leonid, et al.
(författare)
-
The cost of travel time variability : Three measures with properties
- 2016
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Ingår i: Transportation Research Part B. - : Elsevier. - 0191-2615 .- 1879-2367. ; 91, s. 555-564
-
Tidskriftsartikel (refereegranskat)abstract
- This paper explores the relationships between three types of measures of the cost of travel time variability: measures based on scheduling preferences and implicit departure time choice, Bernoulli type measures based on a univariate function of travel time, and mean-dispersion measures. We characterise measures that are both scheduling measures and mean-dispersion measures and measures that are both Bernoulli and mean-dispersion. There are no measures that are both scheduling and Bernoulli. We consider the impact of requiring that measures are additive or homogeneous, proving also a new strong result on the utility rates in an additive scheduling measure. These insights are useful for selecting cost measures to use in applications.
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| 37. |
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| 38. |
- Engelson, Leonid, 1955-, et al.
(författare)
-
The role of volume-delay functions in forecasting and evaluating congestion charging schemes: the Stockholm case
- 2015
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Ingår i: Transportation planning and technology (Print). - : Routledge. - 0308-1060 .- 1029-0354. ; 38:6, s. 684-707
-
Tidskriftsartikel (refereegranskat)abstract
- AbstractThis paper uses observations from before and during the Stockkholm congestion charging trial in order to validate and improve a transportation model for Stockholm. The model overestimates the impact of the charges on traffic volumes while at the same time it substantially underestimates the impact on travel times. These forecast errors lead to considerable underestimation of economic benefits which are dominated by travel time savings. The source of error lies in the static assignment that is used in the model. Making the volume-delay functions (VDFs) steeper only marginally improves the quality of forecast but strongly impacts the result of benefit calculations. We therefore conclude that the dynamic assignment is crucial for an informed decision on introducing measures aimed at relieving congestion. However, in the absence of such a calibrated dynamic model for a city, we recommend that at least a sensitivity analysis with respect to the slope of VDFs is performed.
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| 39. |
- Fosgerau, Mogens, et al.
(författare)
-
Commuting for meetings
- 2014
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Ingår i: Journal of Urban Economics. - : Elsevier BV. - 0094-1190 .- 1095-9068. ; 81, s. 104-113
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Tidskriftsartikel (refereegranskat)abstract
- Urban congestion causes travel times to exhibit considerable variability, which leads to coordination problems when people have to meet. We analyze a game for the timing of a meeting between two players who must each complete a trip of random duration to reach the meeting, which does not begin until both are present. Players prefer to depart later and also to arrive sooner, provided they do not have to wait for the other player. We find a unique Nash equilibrium, and a continuum of Pareto optima that are strictly better than the Nash equilibrium for both players. Pareto optima may be implemented as Nash equilibria by penalty or compensation schemes.
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| 40. |
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| 41. |
- Fosgerau, Mogens, et al.
(författare)
-
The value of travel time variance
- 2011
-
Ingår i: Transportation Research Part B. - : Elsevier BV. - 0191-2615 .- 1879-2367. ; 45:1, s. 1-8
-
Tidskriftsartikel (refereegranskat)abstract
- This paper considers the value of travel time variability under scheduling preferences that are defined in terms of linearly time varying utility rates associated with being at the origin and at the destination. The main result is a simple expression for the value of travel time variability that does not depend on the shape of the travel time distribution. The related measure of travel time variability is the variance of travel time. These conclusions apply equally to travellers who can freely choose departure time and to travellers who use a scheduled service with fixed headway. Depending on parameters, travellers may be risk averse or risk seeking and the value of travel time may increase or decrease in the mean travel time.
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| 42. |
- Hjorth, Katrine, et al.
(författare)
-
Estimating exponential scheduling preferences
- 2015
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Ingår i: Transportation Research Part B. - : Elsevier. - 0191-2615 .- 1879-2367. ; 81:1, s. 230-251
-
Tidskriftsartikel (refereegranskat)abstract
- Different assumptions about travelers' scheduling preferences yield different measures of the cost of travel time variability. Only few forms of scheduling preferences provide non-trivial measures which are additive over links in transport networks where link travel times are arbitrarily distributed independent random variables. Assuming smooth preferences, this holds only for specifications with a constant marginal utility of time at the origin and an exponential or affine marginal utility of time at the destination. We apply a generalized version of this model to stated preference data of car drivers' route and mode choice under uncertain travel times. Our analysis exposes some important methodological issues related to complex non-linear scheduling models. One issue is identifying the point in time where the marginal utility of being at the destination becomes larger than the marginal utility of being at the origin. Another issue is that models with the exponential marginal utility formulation suffer from empirical identification problems. Though our results are not decisive, they partly support the constant-affine specification, in which the value of travel time variability is proportional to the variance of travel time.
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| 43. |
- Kristoffersson, Ida, 1980-, et al.
(författare)
-
A dynamic transportation model for the Stockholm area : Implementation issues regarding departure time choice and OD-pair reduction
- 2009
-
Ingår i: Networks and Spatial Economics. - : Springer Science and Business Media LLC. - 1566-113X .- 1572-9427. ; 9:4, s. 551-573
-
Tidskriftsartikel (refereegranskat)abstract
- Road traffic congestion is an increasing problem in urban areas. Building new roads often attracts latent demand and turns parts of the city into building sites for several years. Policy measures that stimulate more effective use of the existing network, such as variable road pricing, are therefore becoming increasingly popular among policy makers and citizens. These measures are often aimed at changing the temporal distribution of traffic. Yet transportation models taking departure time choice into account are rare. This paper describes the implementation of an urban transportation application for Stockholm, which includes departure time choice, mode choice and time dependent network assignment. Through iterations between demand and supply the objective of the transportation model is to forecast effects of congestion charges, intelligent transport systems and infrastructure investments on departure time choice. The complexity of large-scale departure time choice modelling and dynamic traffic assignment is high, which results in very long run times. Therefore, research on how to increase model efficiency is needed. This paper describes choices made in the implementation for a more efficient model.
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| 44. |
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| 45. |
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| 46. |
- Kristoffersson, Ida, et al.
(författare)
-
Alternative road pricing schemes and their equity effects: Results of simulations for Stockholm
- 2011
-
Ingår i: Proceedings of the TRB 90th Annual Meeting. - Washington, D.C..
-
Konferensbidrag (refereegranskat)abstract
- This paper uses a newly developed transport model to analyze effects of alternative road pricing schemes. The responses to road pricing included in the model are departure time, mode and route choice. Traffic analysis is performed on a large urban network of Stockholm using mesoscopic simulation. The compared pricing schemes differ in toll location and charged amount. Through calculation of consumer surplus per geographical zone, effects of the road pricing schemes are analyzed per income group and geographical area in order to study equity effects. Simulation results suggest that road pricing can be both regressive and progressive depending on the design of the pricing scheme, this even before the use of revenues to compensate users. Results also indicate that there can be a disagreement between which pricing scheme is preferable from a congestion mitigating point of view and which is preferable when looking at equity effects.
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| 47. |
- Kristoffersson, Ida
(författare)
-
Congestion Charging in Urban Networks : Modelling Issues and Simulated Effects
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the major challenges cities face today, in their development towards sustainable urban areas, is the need for an efficient and environmentally friendly transport system. This transport system should manage to tie together the city without strong adverse impact on urban environment, air-quality and climate change. The specialized labour (and leisure) market, typical of a large urban area, exaggerates the need for efficient travel, as it is increasingly difficult to live and work within short distances. The use of demand management tools has become more frequent in transport planning with this development towards more sustainable cities. Whereas investing in new capacity was previously the main response to increased demand for travel, there is a much broader range of policies in use today. One of these demand management tools is congestion charging. Singapore was first to implement congestion charging and during the last decade it was followed by London and Stockholm, with increasing support from the citizens as a consequence. Many other cities have performed feasibility studies for introduction of congestion charging. The development of transport models for prediction of demand management tools, such as congestion charging, has however not been able to keep up with this change in kind of policy. Transport models that were developed for prediction and evaluation of infrastructure investments, such as new motorways, are often used to forecast effects of policies aimed at managing demand, which too often results in poor prediction. This thesis focuses on the needs for modelling of congestion charging. The state-of-practice models used before implementation in Singapore, London and Stockholm are reviewed, as well as more advanced dynamic models developed for prediction of congestion charging and other demand management tools. A number of gaps in the modelling of congestion charging are described and a new model called SILVESTER is developed, which closes some of these gaps. In particular, SILVESTER involves dynamic mesoscopic modelling of traffic flows, flexible departure times and users with heterogeneous preferences. The thesis describes the implementation of SILVESTER and considers and compares different methods of demand aggregation in order to reduce run-time of the large-scale dynamic model (Paper I). It also describes how preferred departure times of road users can be determined in calibration such that consistency exists between the departure time choice model and dynamic traffic flows which are input to assignment (Paper II). The unique implementation of congestion charging in Stockholm gives the possibility to validate SILVESTER on real-world measurement of reductions in traffic flow and behavioural adjustments to the charges (Paper III). SILVESTER is then used to analyse several modified versions of the Stockholm congestion charging scheme and to compare welfare and equity effects of the different schemes. It is shown that the welfare of the current scheme could be improved if charges were allowed to differ by location and driving direction (Paper IV). It is shown that the benefits of congestion charges calculated using SILVESTER are greater than the benefits calculated with a static model. Finally, the reasons for the greater benefits are investigated (Paper V).
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| 48. |
- Kristoffersson, Ida, 1980-, et al.
(författare)
-
Efficiency vs equity : Conflicting objectives of congestion charges
- 2017
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Ingår i: Transport Policy. - : Elsevier Ltd. - 0967-070X .- 1879-310X. ; 60, s. 99-107
-
Tidskriftsartikel (refereegranskat)abstract
- This paper analyses the trade-off between equity and efficiency in the design of the Stockholm congestion charging systems. Comparing different designs for Stockholm, the paper shows that the most efficient system is the least equitable. Indeed, we show that moving towards a more efficient system design favours high-income-users most. The reason is the uneven distribution of workplaces and residential areas, combined with richer socio-economic groups living in areas with more workplaces. Hence, the conflict between efficiency and equity of this policy arises from the spatial mismatch of residential areas and locations of employment, and the spatial separation between low-income and high-income groups that characterise most cities. This paper shows that these spatial patterns have a large effect on the distribution effects of the congestion charges and that the system design can have a major impact on equity.
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| 49. |
- Kristoffersson, Ida, et al.
(författare)
-
Estimating preferred departure times of road users in a large urban network
- 2018
-
Ingår i: Transportation. - : Elsevier. - 0049-4488 .- 1572-9435. ; 45:3, s. 767-787
-
Tidskriftsartikel (refereegranskat)abstract
- In order to reliably predict and assess effects of congestion charges and other congestion mitigating measures, a transportation model including dynamic assignment and departure time choice is important. This paper presents a transport model that incorporates departure time choice for analysis of road users’ temporal adjustments and uses a mesoscopic traffic simulation model to capture the dynamic nature of congestion. Departure time choice modelling relies heavily on car users’ preferred times of travel and without knowledge of these no meaningful conclusions can be drawn from application of the model. This paper shows how preferred times of travel can be consistently derived from field observations and conditional probabilities of departure times using a reverse engineering approach. It is also shown how aggregation of origin–destination pairs with similar preferred departure time profiles can solve the problem of negative solutions resulting from the reverse engineering equation. The method is shown to work well for large-scale applications and results are given for the network of Stockholm.
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| 50. |
- Kristoffersson, Ida, 1980-, et al.
(författare)
-
Estimating preferred departure times of road users in a real-life network
- 2008
-
Ingår i: Proceedings of the European Transport Conference 2008.
-
Konferensbidrag (refereegranskat)abstract
- The demand for travel continues to increase in European cities of today, which results in long car travel times and highly congested road networks, especially during the morning and afternoon peak periods. The congested car system gives rise to high emissions of particles and greenhouse-gases, which is negative for both the local and global environment. Congestion also causes an uncertain travel time, something that in the latest years has been recognised as a major factor in car-users perception of trip disutility. Congestion is time-dependent in nature. Therefore, not only the spatial distribution of trips over the network is important in analysis and prediction, but also the temporal distribution of trips. A traditional congestion-relieving strategy such as a capacity expansion often has an impact on when people travel, since shorter travel times during the peak hour can attract traffic from the peak shoulders. The temporal effects are even more pronounced for the new policy measures gaining ground today, e.g. variable road pricing. Most variable road pricing systems aim at moving traffic from the peak hour to the peak shoulders, so called peak spreading. The means by which this is done is by charge differentiation: it is most expensive to travel at the most congested point in time. However, most large-scale transport planning models in use today are static and changes in the temporal distribution of trips are not considered. It is therefore likely that false conclusions are drawn when using these models to evaluate the ability of different pricing schemes or infrastructure investments to alleviate congestion.SILVESTER – A Dynamic Transport ModelTo better model the temporal distribution of traffic has been the basis in the development of SILVESTER (SImuLation of choice betWEen Sarting TimEs and Routes), which is a dynamic transport model for the Stockholm area. In SILVESTER road network conditions during the extended morning peak period (06:30-09:30) are modelled. The morning is divided into twelve 15-minute time intervals and a departure time choice model allocates trips to each interval depending on their attractiveness. The attractiveness of a time interval is determined by its corresponding travel time, travel time uncertainty, monetary cost and how close it is to the preferred time interval (PDT) of the traveller. The travellers can also choose to start before 06:30 or after 09:30. Mode choice is partially modelled by introducing the possibility for car-users to switch to public transport if it is perceived as a better option than any of the time intervals. It is distinguished between three trip purposes: business trips, trips with fixed schedule and school trips, and trips with flexible schedule and other trips. In SILVESTER iteration towards a general equilibrium between supply and demand is performed. The supply quantities (travel times, uncertainties etc.) are calculated with the mesoscopic dynamic traffic assignment model CONTRAM, whereas the demand for each time interval and public transport alternative is calculated with a mixed logit discrete choice model. A calibrated origin-destination-matrix (OD-matrix) for the Stockholm CONTRAM network exists and is based mainly on traffic counts but also on travel times for some selected OD-pairs. Calibration of Preferred Departure TimesEven though many trip-timing models use the concept of schedule delay, which is defined as the deviation from a preferred departure/arrival time, little work has been done on how to find the PDT-distribution when applying the model. For estimation the survey respondents can be asked to state their preferred time of travel, but for large-scale applications similar studies are expensive and time consuming. Previous work has often assumed a simplified distribution, such as all travellers in a market segment having the same PDT. Without calibration of PDT’s, e.g. using only a simplified exogenous assumption, the predictive capability of the transport model is questionable. Instead of making an exogenous assumption about the PDT-distribution this paper uses a reverse engineering approach to reveal PDT’s from the observed departure times of the reference situation. It is the combination of the estimated departure time choice model, the travel conditions and the observed departure times that can be used to get information about the PDT’s. Once the PDT’s have been calibrated for the reference situation they can be used in the evaluation of a congestion relieving strategy. This paper will present calibration methodology, obstacles overcome on the way and calibration results. It will also discuss future work in which the calibrated departure time choice model will be used to improve the design (charge levels and time periods) of a pricing scheme.
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