| 1. |
- Ait Ali, Abderrahman, 1991-, et al.
(författare)
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A disaggregate bundle method for train timetabling problems
- 2020
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Ingår i: Journal of Rail Transport Planning & Management. - : Elsevier BV. - 2210-9706 .- 2210-9714. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- The train timetabling problem (TTP) consists of finding a feasible timetable for a number of trains which minimises some objective function, e.g., sum of running times or deviations from ideal departure times. One solution approach is to solve the dual problem of the TTP using so-called bundle methods. This paper presents a new bundle method that uses disaggregate data, as opposed to the standard bundle method which in a certain sense relies on aggregate data. We compare the disaggregate and aggregate methods on realistic train timetabling scenarios from the Iron Ore line in Northern Sweden. Numerical results indicate that the proposed disaggregate method reaches better solutions faster than the standard aggregate approach.
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| 2. |
- Ait-Ali, Abderrahman, 1991-, et al.
(författare)
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Are commuter train timetables consistent with passengers’ valuations of waiting times and in-vehicle crowding?
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Many models have been developed and used to analyse the costs and benefits of transport investments. Similar tools can also be used for transport operation planning and capacity allocation. An example of such use is the assessment of commuter train operations and service frequency. In this study, we analyse the societally optimal frequency for commuter train services. The aim is to reveal the implicit valuation (by the public transport agency) of the waiting time and the in-vehicle crowding in the commuting system. We use an analytic CBA model to formulate the societal costs of a certain service frequency and analyse the societally optimal frequencies during peak and off-peak hours. Comparing the optimal and the actual frequencies allows to reveal the implicit valuations of waiting time and crowding. Using relevant data from the commuter train services in Stockholm on a typical working day in September 2015 (e.g., OD matrix, cost parameters), we perform a numerical analysis on certain lines and directions. We find the societally optimal frequency and the implicit valuation of waiting time and crowding. The results suggest that the public transport agency in Stockholm (i.e., SL) adopted service frequencies that are generally slightly higher than societally optimum which can be explained by a higher implicit valuation of waiting time and crowding. We also find that the optimal frequencies are more sensitive to the waiting time valuation rather than that of crowding.
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| 3. |
- Ait-Ali, Abderrahman, 1991-, et al.
(författare)
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Are commuter train timetables consistent with passengers’ valuations of waiting times and in-vehicle crowding?
- 2022
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Ingår i: Transport Policy. - : Elsevier BV. - 0967-070X .- 1879-310X. ; 116, s. 188-198
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Tidskriftsartikel (refereegranskat)abstract
- Social cost-benefit analysis is often used to analyse transport investments, and can also be used for transport operation planning and capacity allocation. If it is to be used for resolving capacity conflicts, however, it is important to know whether transit agencies' timetable requests are consistent with the cost-benefit framework, which is based on passenger preferences. We show how a public transport agency's implicit valuations of waiting time and crowding can be estimated by analysing timetables, apply the method to commuter train timetables in Stockholm, and compare the implicit valuations to the corresponding passenger valuations in the official Swedish cost-benefit analysis guidelines. The results suggest that the agency puts a slightly lower value on waiting time and crowding than the passenger valuations codified in the official guidelines. We discuss possible reasons for this and implications for using cost-benefit analysis for capacity allocation. We also find that optimal frequencies are more sensitive to the waiting time valuation than to that of crowding.
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| 4. |
- Ait Ali, Abderrahman, 1991-, et al.
(författare)
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European Railway Deregulation : An overview of market organization and capacity allocation
- 2022
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Ingår i: Transportmetrica A. - : Taylor & Francis. - 2324-9935 .- 2324-9943. ; 18:3, s. 594-618
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Tidskriftsartikel (refereegranskat)abstract
- Railway markets in Europe have been reorganized to allow competition between different operators. Thus, European railways have been vertically separated, separating infrastructure management from provisions of train services. This allows several train operators to compete for passengers and freight services. Different ways have emerged for vertical separation, capacity allocation and track access charges. This paper reviews, compares and discusses important deregulation aspects, using examples from a number of European countries to show different possible solutions. The study describes how competition has been introduced and regulated, with a particular focus on describing the different ways capacity is allocated and how conflicting requests by different train operators are resolved. It also reviews the related issue of how access charges are constructed and applied. Although guided by the same European legislation, we conclude that the studied railways have different deregulation outcomes, e.g., market organization, capacity allocation. Besides, few countries have so far managed to create efficient and transparent processes for allocating capacity between competing train operators. Although allowed by the legislation, market-based allocation is absent or never used. In order to foster more competition which can yield substantial social benefits, the survey indicates that most European railways still need to develop and experiment with more efficient and transparent capacity allocation procedures.
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| 5. |
- Ait-Ali, Abderrahman, 1991-, et al.
(författare)
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Pricing commercial train path requests based on societal costs
- 2020
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Ingår i: Transportation Research Part A. - : Elsevier. - 0965-8564 .- 1879-2375. ; 132, s. 452-464
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Tidskriftsartikel (refereegranskat)abstract
- On deregulated railway markets, efficient capacity allocation is important. We study the case where commercial trains and publicly controlled traffic (“commuter trains”) use the same railway infrastructure and hence compete for capacity. We develop a method that can be used by an infrastructure manager trying to allocate capacity in a socially efficient way. The method calculates the loss of societal benefits incurred by changing the commuter train timetable to accommodate a commercial train path request, and based on this calculates a reservation price for the train path request. If the commercial operator's willingness-to-pay for the train path exceeds the loss of societal benefits, its request is approved. The calculation of these benefits takes into account changes in commuter train passengers’ travel times, waiting times, transfers and crowding, and changes in operating costs for the commuter train operator(s). The method is implemented in a microscopic simulation program, which makes it possible to test the robustness and feasibility of timetable alternatives. We show that the method is possible to apply in practice by demonstrating it in a case study from Stockholm, illustrating the magnitudes of the resulting commercial train path prices. We conclude that marginal societal costs of railway capacity in Stockholm are considerably higher than the current track access charges.
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| 6. |
- Ait-Ali, Abderrahman, 1991-, et al.
(författare)
-
Pricing commercial train path requests based on societal costs
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- On deregulated railway markets, efficient capacity allocation is important. We study the case where commercial trains and publicly controlled traffic (“commuter trains”) use the same railway infrastructure and hence compete for capacity. We develop a method that can be used by an infrastructure manager trying to allocate capacity in a socially efficient way. The method calculates the loss of social benefits incurred by changing the commuter train timetable to accommodate a commercial train path request and based on this calculates a reservation price for the train path request. If the commercial operator’s willingness-to-pay for the train path exceeds the loss of social benefits, its request is approved. The calculation of social benefits takes into account changes in commuter train passengers’ travel times, waiting times, transfers and crowding, and changes in operating costs for the commuter train operator(s). The method is implemented in a microscopic simulation program, which makes it possible to test the robustness and feasibility of timetable alternatives. We show that the method is possible to apply in practice by demonstrating it in a case study from Stockholm, illustrating the magnitudes of the resulting commercial train path prices. We conclude that marginal societal costs of railway capacity in Stockholm are considerably higher than the current track access charges.
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| 7. |
- Ait-Ali, Abderrahman, 1991-, et al.
(författare)
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Railway capacity allocation : a survey of market organizations, allocation processes and track access charges
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the last few decades, many railway markets (especially in Europe) have been restructured to allow competition between different operators. This survey studies how competition has been introduced and regulated in a number of different countries around the world. In particular, we focus on a central part of market regulation specific to railway markets, namely the capacity allocation process. Conflicting capacity requests from different train operators need to be regulated and resolved, and the efficiency and transparency of this process is crucial. Related to this issue is how access charges are constructed and applied. Several European countries have vertically separated their railway markets, separating infrastructure management from train services provisions, thus allowing several train operators to compete with different passengers and freight services. However, few countries have so far managed to create efficient and transparent processes for allocating capacity between competing train operators, and incumbent operators still have larger market-share in many markets.
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| 8. |
- Ait-Ali, Abderrahman, 1991-, et al.
(författare)
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The value of additional data for public transport origin-destination matrix estimation
- 2022
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Ingår i: Public Transport. - : Springer Science+Business Media B.V.. - 1866-749X .- 1613-7159. ; 14:2, s. 419-439
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Tidskriftsartikel (refereegranskat)abstract
- Passenger origin–destination data is an important input for public transport planning. In recent years, new data sources have become increasingly common through the use of the automatic collection of entry counts, exit counts and link flows. However, collecting such data can be sometimes costly. The value of additional data collection hence has to be weighed against its costs. We study the value of additional data for estimating time-dependent origin–destination matrices, using a case study from the London Piccadilly underground line. Our focus is on how the precision of the estimated matrix increases when additional data on link flow, destination count and/or average travel distance is added, starting from origin counts only. We concentrate on the precision of the most policy-relevant estimation outputs, namely, link flows and station exit flows. Our results suggest that link flows are harder to estimate than exit flows, and only using entry and exit data is far from enough to estimate link flows with any precision. Information about the average trip distance adds greatly to the estimation precision. The marginal value of additional destination counts decreases only slowly, so a relatively large number of exit station measurement points seem warranted. Link flow data for a subset of links hardly add to the precision, especially if other data have already been added.
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| 9. |
- Anderstig, Christer, et al.
(författare)
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Congestion charges and labour market imperfections : “wider economic benefits” or “losses”?
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The presence of distortive taxation and agglomeration benefits in the labour market means that there are benefits and losses not captured by standard cost-benefit analyses of transport policy measures. Recent theoretical analyses have raised concerns that the labour market effects of congestion charges may constitute considerable losses in the form of reduced aggregate labour income, over and above what is captured by the consumer surplus in the standard analysis of congestion charges – possibly to the extent that congestion charges may reduce aggregate social welfare, contrary to conventional wisdom in transport economics. The sign and size of these effects are an empirical question, however. We investigate this issue by estimating the labour income effects of the Stockholm congestion charges, using an estimated relationship between workplace accessibility and labour income. Results show positive effects on labour income, meaning that the “wider economic benefits” of this system are in fact benefits, not losses. It turns out to be crucial that the model accounts for value-of-time heterogeneity in the income/accessibility relationship and in the calculation of generalized travel costs.
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| 10. |
- Asplund, Disa, 1985-, et al.
(författare)
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Does uncertainty make cost-benefit analyses pointless?
- 2016
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Ingår i: Transportation Research Part A. - Stockholm : Elsevier BV. - 0965-8564 .- 1879-2375. ; 92, s. 195-205
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Tidskriftsartikel (refereegranskat)abstract
- Cost-benefit analysis (CBA) is widely used in public decision making on infrastructure investments. However, the demand forecasts, cost estimates, benefit valuations and effect assessments that are conducted as part of CBAs are all subject to various degrees of uncertainty. The question is to what extent CBAs, given such uncertainties, are still useful as a way to prioritize between infrastructure investments, or put differently, how robust the policy conclusions of CBA are with respect to uncertainties. Using simulations based on real data on national infrastructure plans in Sweden and Norway, we study how investment selection and total realized benefits change when decisions are based on CBA assessments subject to several different types of uncertainty.Our results indicate that realized benefits and investment selection are surprisingly insensitive to all studied types of uncertainty, even for high levels of uncertainty. The two types of uncertainty that affect results the most are uncertainties about investment cost and transport demand. Provided that decisions are based on CBA outcomes, reducing uncertainty is still worthwhile, however, because of the huge sums at stake. Even moderate reductions of uncertainties about unit values, investment costs, future demand and project effects may increase the realized benefits infrastructure investment plans by tens or hundreds of million euros. We conclude that, despite the many types of uncertainties, CBA is able to fairly consistently separate the wheat from the chaff and hence contribute to substantially improved infrastructure decisions.
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