| 1. |
- Beser Hugosson, Muriel
(författare)
-
Quantifying uncertainties in a national forecasting model
- 2005
-
Ingår i: Transportation Research Part A. - : Elsevier BV. - 0965-8564 .- 1879-2375. ; 39:6, s. 531-547
-
Tidskriftsartikel (refereegranskat)abstract
- Uncertainties related to demand model system outputs is an important issue in travel demand models. This paper focuses on uncertainties arisen from the fact that models are estimated on a sample of the population (and not the whole population). Forecasting systems can be quite complex, and may contain procedures that not easily permit analytically derived statistical measures of uncertainty. In this paper, the possibilities to use computer-intensive numerical methods to compute statistical measures for very complex systems, without being bound to an analytical approach, are explored. Here, the bootstrap method is used to obtain statistical measures of outputs produced by the forecasting system SAMPERS. The SAMPERS system is used by Swedish transport authorities. The bootstrap method is briefly described as well as the procedure of applying bootstrap on the SAMPERS system. Numerical results are presented for selected forecast results at different levels such as total traffic demand, origin-destination demand, train line demand and the demand on specific links. Also, the uncertainty related to the value of time estimate is analysed.
|
|
| 2. |
- Beser Hugosson, Muriel, et al.
(författare)
-
The Stockholm congestion charging system : an overview of the effects after six months
- 2006
-
Ingår i: Proceedings of European Transport Conference 2006.
-
Konferensbidrag (refereegranskat)abstract
- The Expert Group consists of eight traffic experts with various specialities. The group read all documentation and then, during three intensive full-day seminars, drew the conclusions presented in this summary of the evaluation of the Stockholm Trial. Several group members have in different ways participated in preparatory tasks prior to the evaluation and also conducted follow-up activities during the course of the trial.The Expert Group is chaired by Dr Jonas Eliasson, Transek AB and its secretary is Dr Lena Smidfeldt Rosqvist, Trivector Traffic AB. Other members are Associate Prof. Staffan Algers, Royal Institute of Technology/Transek, Dr Karin Brundell-Freij Engineering Faculty, Lund University, Managing Director of Inregia AB Cecilia Henriksson, Inregia AB, Prof. Lars Hultkrantz, Örebro University and scientific advisor to the Swedish Road and Transport Research Institute., Managing Director of Trivector Traffic AB Christer Ljungberg and Dr Lena Nerhagen, Swedish National Road and Transport Research Institute
|
|
| 3. |
|
|
| 4. |
- Gudmundsson, Henrik, et al.
(författare)
-
Framing the role of Decision Support in the case of Stockholm Congestion Charging Trial
- 2009
-
Ingår i: Transportation Research. Part A: Policy & Practice. - : Elsevier BV. - 0965-8564. ; 43:3, s. 258-268
-
Tidskriftsartikel (refereegranskat)abstract
- Congestion charging was - as a trial - introduced in Stockholm from January 3rd to July 31st 2006. After the referendum in September 2006, the charging system was finally introduced as permanent from August 2007 with some adjustments to the Trial design. The idea of congestion charging is unique in a Swedish context. and the introduction of the Stockholm system has been highly controversial. Considerable efforts have therefore been undertaken to provide information that could serve as 'Decision Support' along the way. This has included e.g. modelling and forecasts before the Trial, a comprehensive evaluation programme during the Trial, extensive stakeholder consultations throughout, and various information and communication strategies. But what difference did this information input make, and what was its role in the process from initiating the system, to its final adoption? In this paper we pave the way for investigating the use and role of 'Decision Support' in the Stockholm Congestion Charging experiment. We adopt a definition of Decision Support as the systematic application of externally produced knowledge in transport planning and policy making processes. We then derive an analytical framework from the research literature on 'knowledge utilization' in policy making. This research has generally found that both 'technical', 'communicative', and 'institutional' aspects of the Decision Support matter for its influence on actual policy making processes and results. In our analysis we find a similar pattern. This high technical quality of the monitoring and evaluation programmes provided for solid verified results, while the institutional arrangements and the communication strategies helped to ensure the credibility and legitimacy of the information for the decision makers. The availability of rich contents coupled with strategies for the timely and targeted information delivery suggest that direct 'instrumental' use could have taken place. At a more general level the Trial represents an advanced form of 'Decision Support' that goes beyond the mere application of calculated results to encompass a process where the decision parameters themselves become part of the change process. (C) 2008 Elsevier Ltd. All rights reserved.
|
|
| 5. |
- Morán Toledo, Carlos A., 1976-
(författare)
-
Framework for Estimating Congestion performance measures : from data collection to reliability analysis: case study of Stockholm
- 2008
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For operational and planning purposes it is important to observe and predict the traffic performance of congested urban road links and networks. Congestion can be defined as traffic conditions caused by a downstream bottleneck or excess in travel time from what is incurred during light or free-flow travel conditions. Factors affecting definitions of congestion for specific studies are reviewed and an inventory of proposed congestion performance measures is presented for both definitions of congestion.Swedish Road Administration has recognized the reliability of the estimations of congestion levels as an important factor when describing the traffic condition in the road traffic network. Traffic data collected for the Stockholm congestion charging trials was used to estimate selected congestion performance measures and to analyze their statistical characteristics and applicability. A comparative analysis of data collection methods is provided and further recommendations for their using estimating Congestion Performance Measures.The reliability of the estimations of each Congestion Performance Measure is evaluated for different area networks and different time periods of the day. These series of observations are further studied aiming to identify systematic differences in the reliability of the estimations. A reliability ranking is provided for guiding future studies in the selection of estimators. Further, a simplify methodology for estimating recommended sample sized under budget restricted conditions is provided.
|
|
