Mode choice is important in shipping commodities efficiently. This paper develops a binary logit model and a regression model to study the cereal grains movement by truck and rail in the United States using the public...Mode choice is important in shipping commodities efficiently. This paper develops a binary logit model and a regression model to study the cereal grains movement by truck and rail in the United States using the publically available Freight Analysis Framework (FAF2.2) database and U.S. highway and networks and TransCAD, a geographic information system with strong transportation modeling capabilities. The binary logit model and the regression model both use the same set of generic variables, including mode split probability, commodity weight, value, network travel time, and fuel cost. The results show that both the binary logit and regression models perform well for cereal grains transportation in the United States, with the binary logit model yielding overall better estimates with respect to the observed truck and rail mode splits. The two models can be used to study other commodities between two modes and may produce better results if more mode specific variables are used.展开更多
Bridges are critical but vulnerable elements of a highway transportation system.A bridge collapse not only affects the freight movement on the bridge but also the flow in the entire network,posing negative impacts on ...Bridges are critical but vulnerable elements of a highway transportation system.A bridge collapse not only affects the freight movement on the bridge but also the flow in the entire network,posing negative impacts on local,regional,and national economy.This study examines the spatial and economic impact of the 2002 I-40 Bridge collapse in Oklahoma on freight flow movement in the U.S.highway network.Freight Analysis Framework(FAF)databases,TransCADTM software,and two assignment models(All-or-Nothing and User Equilibrium)are used to analyze the freight flow changes before and after the bridge collapse along with two different freight assignment approaches.The first approach assigns the origin-destination freight flow to the network with the collapsed bridge removed.The second involves two successive assignments-first by excluding the pre-hazard freight flow on the bridge and assigning the rest of the flow to the post-disaster network,and second,by assigning the freight flow on the bridge in pre-disaster conditions to the post-disaster-network.The research showed that the bridge collapse did not only impact the freight flows on nearby highway network links,but also affected flows on links further away from the bridge.This finding casts doubts on the conventional models relying on gravity-based spatial distance decay effects,which often overestimate the nearby but underestimate the further-out freight flow changes in the network.展开更多
文摘Mode choice is important in shipping commodities efficiently. This paper develops a binary logit model and a regression model to study the cereal grains movement by truck and rail in the United States using the publically available Freight Analysis Framework (FAF2.2) database and U.S. highway and networks and TransCAD, a geographic information system with strong transportation modeling capabilities. The binary logit model and the regression model both use the same set of generic variables, including mode split probability, commodity weight, value, network travel time, and fuel cost. The results show that both the binary logit and regression models perform well for cereal grains transportation in the United States, with the binary logit model yielding overall better estimates with respect to the observed truck and rail mode splits. The two models can be used to study other commodities between two modes and may produce better results if more mode specific variables are used.
文摘Bridges are critical but vulnerable elements of a highway transportation system.A bridge collapse not only affects the freight movement on the bridge but also the flow in the entire network,posing negative impacts on local,regional,and national economy.This study examines the spatial and economic impact of the 2002 I-40 Bridge collapse in Oklahoma on freight flow movement in the U.S.highway network.Freight Analysis Framework(FAF)databases,TransCADTM software,and two assignment models(All-or-Nothing and User Equilibrium)are used to analyze the freight flow changes before and after the bridge collapse along with two different freight assignment approaches.The first approach assigns the origin-destination freight flow to the network with the collapsed bridge removed.The second involves two successive assignments-first by excluding the pre-hazard freight flow on the bridge and assigning the rest of the flow to the post-disaster network,and second,by assigning the freight flow on the bridge in pre-disaster conditions to the post-disaster-network.The research showed that the bridge collapse did not only impact the freight flows on nearby highway network links,but also affected flows on links further away from the bridge.This finding casts doubts on the conventional models relying on gravity-based spatial distance decay effects,which often overestimate the nearby but underestimate the further-out freight flow changes in the network.
