Statement of retraction

„Statement of retraction" Transport, 27(3), p. 34

Stochastic Risk vs. Policy Oriented Uncertainties: The Case of the Alpine Crossings

This paper focuses on uncertainties in traffic forecasting. Three major sources of uncertainties are observed for freight demand models. The first one is the model specification itself. We are not interested by it. The second one concerns uncertainties over forecasting hypotheses. A mean to control such uncertainties lies in the introduction of risk in the Costs Benefits Analysis (CBA). Two directions have been taken by this research. The first one is the theoretical framework of CBA under uncertainty mainly developed after Dixit and Pindyck (1994). The second one is more empirical and uses Monte Carlo simulations. Major results of these researches are presented. Then, we apply them to a large transport investment simulation. These tools cannot be used for all kinds of uncertainties. The second part of this paper deals with the third source of uncertainties i. e. policy oriented uncertainties. For them, previous methods are useless. The current Alpine crossings context shows that transport policy is a major determinant of traffics. Furthermore, long term forecasting cannot exclude the possibility of changes in transport policy. This uncertainty should be controlled. It is the role of strategic modeling.risk ; uncertainty ; traffic forecasting ; Monte Carlo simulation ; transport policy ; Strategic models ; Alpine crossings

Transportation Implications of Coal

This report describes the direct economic relationship between the coal and railroad industries in Appalachia. It finds that between 2015 and 2016, changing electric generation strategies—including accelerated coal-powered plant retirements—combined with a downturn in coal demand contributed to losses of nearly 2,000 full-time jobs and $150 million in income across Appalachia’s railroad sector

Impact and relevance of transit disturbances on planning in intermodal container networks

__Abstract__ An intermodal container transportation network is being developed between Rotterdam and several inland terminals in North West Europe: the European Gateway Services network. This network is developed and operated by the sea terminals of Europe Container Terminals (ECT). To use this network cost-efficiently, centralised planning by the sea terminal of the container transportation is required. For adequate planning it is important to adapt to occurring disturbances. In this paper, a new mathematical model is proposed: the Linear Container Allocation model with Time-restrictions (LCAT). This model is used for determining the influence of three main types of transit disturbances on the network performance: early departure, late departure, and cancellation of inland services. The influence of a disturbance is measured in two ways. The impact measures the additional cost incurred by an updated planning in case of a disturbance. The relevance measures the cost difference between a fully updated and a locally updated plan. With the results of the analysis, key service properties of disturbed services that result in a high impact or high relevance can be determined. Based on this, the network operator can select focus areas to prevent disturbances with high impact and to improve the planning updates in case of disturbances with high relevance. In a case study of the EGS network, the impact and relevance of transit disturbances on all network services are assessed

Assignment of Freight Traffic in a Large-Scale Intermodal Network under Uncertainty

This paper presents a methodology for freight traffic assignment in a large-scale road-rail intermodal network under uncertainty. Network uncertainties caused by natural disasters have dramatically increased in recent years. Several of these disasters (e.g., Hurricane Sandy, Mississippi River Flooding, Hurricane Harvey) severely disrupted the U.S. freight transport network, and consequently, the supply chain. To account for these network uncertainties, a stochastic freight traffic assignment model is formulated. An algorithmic framework, involving the sample average approximation and gradient projection algorithm, is proposed to solve this challenging problem. The developed methodology is tested on the U.S. intermodal network with freight flow data from the Freight Analysis Framework. The experiments consider four types of natural disasters that have different risks and impacts on the transportation network: earthquake, hurricane, tornado, and flood. The results demonstrate the feasibility of the model and algorithmic framework to obtain freight flows for a realistic-sized network in reasonable time (between 417 and 716 minutes). It is found that for all disaster scenarios the freight ton-miles are higher compared to the base case without uncertainty. The increase in freight ton-miles is the highest under the flooding scenario; this is due to the fact that there are more states in the flood-risk areas and they are scattered throughout the U.S

Investigation of the opportunities for railway based combined freight transport in Turkey

Bu çalışmada, bir ağ modeli geliştirilerek Türkiye’de demiryolu ağırlıklı kombine yük taşımacılığı olanaklarının araştırılması amaçlanmıştır. Geliştirilen model, çeşitli mal gruplarından oluşan yüklerin karayolu ile demiryolunu içeren bir ağ üzerinde taşınmasının benzetimini gerçekleştirmektedir. Yolcu trafiğinin de aynı ağı kullandığı göz önünde tutularak yolcu taşımaları da modelde dikkate alınmaktadır. Modelde yük ve yolcu taşımacılığı için talep, bir matrisler kümesi ile tanımlanmaktadır. Bu yüzden iller arasında gerçekleştirilen yük ve yolcu taşımalarına ait matrisler elde edilmiş ve çoklu regresyon analizi kullanılarak yük ve yolcu taşımalarının ileriye dönük tahmininde kullanılabilecek çekim modeli tarzında denklemler geliştirilmiştir. Karayollarında gerçekleştirilen iller arası yük ve yolcu taşımalarına ait matrislerin belirlenmesi için eksenler bazında verilen araç sayılarından O-D matrisleri oluşturabilen ve Bell tarafından geliştirilen modelden yararlanılmıştır. Demiryolu yük ve yolcu matrislerinin belirlenmesi için TCDD tarafından sağlanan yük taşımalarına ilişkin veriler ile ekspres ve bölgesel yolcu trenleri cetvelleri kullanılmıştır. Karayolu, otoyolu, bağlantı yolları, demiryolu, transfer ve merkez bağlantılarından oluşan bütünleşik ulaştırma ağı ile sadece merkez, karayolu, otoyolu ve bağlantı yollarından oluşan karayolu ağları ve yine sadece merkez ve demiryolu bağlantılarından oluşan demiryolu ağı üzerine yük grupları ve yolcular için elde edilen O-D matrislerinin atamaları gerçekleştirilmiştir. Bu atamalardan sonra hangi demiryolu bağlantılarında sıkışıklık oluşacağı belirlenmiştir. Elde edilen sonuçlara göre Türkiye’de kombine yük taşımacılığının yaygınlaşması için neler yapılması gerektiği tartışılmıştır. Anahtar Kelimeler: Ağ analizi, matris tahmini, çekim modelleri, kombine taşımacılık.If some special cases are excluded, highway transportation is the only mode used to provide the door-to-door movement of goods. Although highway transportation is used commonly, it is not suitable for freight to be carried over long distances because of its cost and environmental impacts. For this reason, more than one mode must be used to carry goods economically and safely. This kind of transportation is called multimodal transport, or intermodal transport, or combined transport and has also been increasing in Turkey. However, in addition to the shortcomings in railway infrastructure, the deficiencies in operating the existing system prevents railways from playing an important role in combined transport. In this study, the requisities that must be brought in to improve the opportunities of combined transport in Turkey have been investigated by developing a network model. The model developed carries out simulating the freight flows consisting of various commercial goods on a multimodal network representing highway and railway modes. The existence of more than one mode between two adjacent regions is represented with parallel links. In order to model transfer of freight between transportation modes, transfer links have been formed. In addition, passenger transportation is taken into account, considering that it also uses the same network. However, it is assumed that travellers determine in advance which transportation mode they will use and that there are no transfers between these transportation modes. Different cost functions are defined for passenger and freight transport. These cost functions depend on the volume of goods and the amount of passenger traffic on the link. Similarly, a cost function is associated with each transfer link. The demand for each product and passenger traffic is specified by a set of O-D matrices. The mode choice for each product and passenger traffic is also indicated by defining for each of these O-D matrices. The demand matrices for passenger transportation are determined separately for highway and railway modes. Highway passenger traffic is also divided into two groups as automobile and bus passenger. The Bell Model that estimates matrices from traffic counts was used to determine the intercity highway passenger and freight transportation matrices. For highway freight transportation, the initial matrices were formed by modelling the observed matrices obtained from roadside interviews with respect to some socioeconomic parameters, using multiple regression analysis. After these freight matrices were used as the initial matrices in Bell?s model,  the other set of matrices that are consistent with the average annual daily truck traffic on 250 highway sections were determined. The matrices obtained for each freight type by using the Bell Model were also analysed statistically. The model developed by Bell was utilized to determine intercity automobile and bus travel matrices. In this case, the principles of Gravity Model were also used to form the initial matrices. After the intercity automobile and bus travel matrices were determined by using Bell?s method, statistical analyses were performed for the O-D information obtained from these matrices. In order to determine the railway freight and passenger matrices, the freigt transport database provided by TCDD and the charts of express and regional passenger trains were used. The multimodal as well as the highway and railway networks were coded, considering all link attributes such as distance, speed, time, and price. The O-D matrices obtained for all freight and passenger types were then assigned onto the related networks, taking into account the unit time values of all freight types and passengers. As a result of these assignments, the freight and passenger volumes carried on links as well as numbers of vehicles and trains were found. For each link, the numbers of vehicles and trains on the links that result from assigning the freight and passenger matrices onto the related networks were added up, and the total numbers of vehicles and trains on links were found. In conclusion, it is seen that the highway, freeway and connection links are not congested, and that some of the railway links carry freight volumes beyond their capacities. Finally, the requisites that must be brought in to improve the possibilities of combined transport in Turkey were discussed, based on the results obtained from this study.  Keywords: Network analysis, matrix estimation, gravity models, combined transport

Multimodal statewide freight transportation modeling process

http://www.worldcat.org/oclc/3927718

Development of a procedure for the statewide distribution and assignment of truck commodity flows: a case study of Iowa

The purpose of this research is to develop a procedure for statewide planning of truck commodity flows and apply it to the State of Iowa. The methodology utilizes available relevant data sources at the state level and state-of-the-art freight transportation planning tools. A case study consisting of two manufacturing sectors and a simplistic transportation network is developed for Iowa to demonstrate the procedure. Difficulties encountered in the modeling process are identified and categorized by cause into modeling capability or data related. Data deficiencies having the greatest impact on the modeling process and the accuracy of the results are identified. Some methods to improve freight data are offered as are estimates of the effort entailed in improving and developing new data;The procedure for the statewide distribution and assignment of truck commodity flows provides a practical tool for state level freight transportation planning. The procedure examines major commodity movements on dense corridors. The general scheme of the methodology is to: (1) identify major commodities shipped in the state; (2) identify producing and attracting zones of the major commodities in the state; (3) estimate truck shipments between origin-destination pairs; and (4) assign estimated truck trips onto the primary highways within the state;Analysis zones within Iowa represent counties, while external analysis zones represent states. The total zonal freight tonnage generated is estimated using socioeconomic indicators, employment and population. Produced manufacturing freight is correlated with employment rates. Attracted freight is allocated to industrial inputs by employment and to consumption using population size. The truck freight share is estimated as the total freight generated less the freight tonnage shipped by rail. A gravity model is used to distribute the estimated truck tonnage among major origin-destination pairs. The impedance factor in the gravity model is equal to the inverse of travel time on links. Estimated truck tonnage is converted to vehicle trips using typical vehicle equivalent weights. Truck trips are assigned to shortest paths calculated using a tree building algorithm. Estimated truck trips are validated against truck counts on selected highway links