Papers by Takanori Sakai
Transportation, 2018
Freight forecasting models have been significantly improved in recent years, especially in the fi... more Freight forecasting models have been significantly improved in recent years, especially in the field of goods vehicle behavior modeling. On the other hand, the improvements to commodity flow modeling, which provide inputs for goods vehicle simulations, were limited. Contributing to this component in urban freight modeling systems, we propose an error component logit mixture model for matching a receiver to a supplier that considers two-layers in supplier selection: distribution channels and specific suppliers. The distribution channel is an important element in freight modeling, as the type of distribution channel is relevant to various aspects of shipments and vehicle trips. The model is estimated using the data from the Tokyo Metropolitan Freight Survey. We demonstrate how typical establishment survey data (i.e. establishment and outbound shipment records) can be used to develop the model. The model captures the correlation structure of potential suppliers defined by business function and provides insights on the differences in the supplier choice by distribution channel. The reproducibility tests confirm the validity of the proposed approach, which is currently integrated into a metropolitan-scale agent-based freight modeling system, for practical use.
Journal of Transport Geography, 2019
Despite the growing research interests on the spatial restructuring of logistics facilities that ... more Despite the growing research interests on the spatial restructuring of logistics facilities that occurred in many cities around the world, the relationship between the spatial pattern of logistics land use and the level of externalities is far from being elucidated. We use the Urban Logistics Land-use and Traffic Simulator (ULLTRA-SIM), developed for the Tokyo Metropolitan Area, to evaluate the level of externalities that accompany different spatial distribution patterns of logistics facilities. The ULLTRA-SIM takes a novel approach to analyze the urban freight impacts through the simulations of logistics facility locations, urban logistics chains, and truck flow. The results indicate that, while the moderate concentration and deconcentration of logistics facilities do not significantly affect the level of externalities, scarcity of logistics facilities in or near the high demand locations exacerbates negative externalities. Also, the results of the simulations underscore the need for rigorous analysis in order to reduce negative externalities through logistics land use policies.
Transportation, 2018
Freight forecasting models have been significantly improved in recent years, especially in the fi... more Freight forecasting models have been significantly improved in recent years, especially in the field of goods vehicle behavior modeling. On the other hand, the improvements to commodity flow modeling, which provide inputs for goods vehicle simulations, were limited. Contributing to this component in urban freight modeling systems, we propose an error component logit mixture model for matching a receiver to a supplier that considers two-layers in supplier selection: distribution channels and specific suppliers. The distribution channel is an important element in freight modeling, as the type of distribution channel is relevant to various aspects of shipments and vehicle trips. The model is estimated using the data from the Tokyo Metropolitan Freight Survey. We demonstrate how typical establishment survey data (i.e. establishment and outbound shipment records) can be used to develop the model. The model captures the correlation structure of potential suppliers defined by business function and provides insights on the differences in the supplier choice by distribution channel. The reproducibility tests confirm the validity of the proposed approach, which is currently integrated into a metropolitan-scale agent-based freight modeling system, for practical use.
Journal of Transport and Land Use, 2018
We analyze the relationship between the location of logistics facilities and the goods vehicle tr... more We analyze the relationship between the location of logistics facilities and the goods vehicle travel distances for the shipments associated with the facilities, using data from a large urban freight survey conducted in the Tokyo Metropolitan Area in 2013. Our analysis categorizes the logistics facilities into groups based on the type of commodity they handle. The analysis sheds light on the complex relationship between the location and “distance optimality gap,” defined as the gap between the minimum travel distance possible and the actual distance traveled by goods vehicles. The results indicate that, while the lack of available space for logistics land use near the urban center leads to significant distance optimality gaps for some logistics facility groups, such as those handling daily goods, these same locations may not be advantageous for others. Also, the logistics facilities in the exurbs are likely to have large distance optimality gaps because these locations are often far away from the origins and destinations of their shipments. In terms of land-use policy, the study reveals that simply concentrating logistics facilities near the urban core or suburbs may not reduce truck traffic. Detailed data on logistics facilities and shipments are crucial for formulating effective approaches to improve the distance optimality of logistics land use.
Transportation Research Record: Journal of the Transportation Research Board, 2018
The concept of “Freight Landscape,” the basis for a modeling approach for urban freight traffic e... more The concept of “Freight Landscape,” the basis for a modeling approach for urban freight traffic estimation using commonly available datasets, was proposed by Giuliano et al., 2017, applying it to the Los Angeles metropolitan area. To extend the scope of their research, we conduct another case study, using data from the Paris region, France. We estimate spatial lag models using population, employment or establishment, transportation accessibilities as explanatory variables and network-based truck traffic as the dependent variable, modifying Giuliano et al.’s approach. We identify differences in the characteristics of the variables and the models between Los Angeles and Paris cases, each having distinctively different urban structure from one another. While the models estimated for the Paris region give us beneficial insights on the relationships between Freight Landscape indicators and urban freight traffic, the complex correlation structure among indicators as well as the limitation of the models to specify the areas of very high truck traffic underlines the need for further research on modeling framework and adding more case studies.
The concept of “Freight Landscape,” the basis for a modeling approach for urban freight traffic e... more The concept of “Freight Landscape,” the basis for a modeling approach for urban freight traffic estimation using commonly available datasets, was proposed by Giuliano et al., 2015, applying it to the Los Angeles metropolitan area. To extend the scope of their research, we conduct another case study, using data from the Paris region, France. We estimate spatial lag models using population, employment or establishment, transportation accessibilities as explanatory variables and network-based truck traffic as the dependent variable, modifying Giuliano et al.’s approach. We identify similarities and differences between the case studies of Los Angeles and Paris. For Paris, the estimated models highlight the most important factors that characterize urban freight traffic in the region, including the distance to autoroutes (controlled-access highways) and jobs in trade, manufacturing of electrical products and machines, and the transportation industry. While the models estimated for the Paris region give us beneficial insights on the relations between Freight Landscape indicators and urban freight traffic, the model validation underlines the needs of further research for a modeling framework that enables unbiased estimation of urban freight traffic.
In existing freight models, the choice of locations for logistics facilities and the choice of lo... more In existing freight models, the choice of locations for logistics facilities and the choice of logistics facilities for routing the shipments are often treated without distinction, although these two decisions are separate and affected by different factors. In this paper, models for choosing a logistics facility are developed that match truck trip ends with logistics facilities by using a large urban freight survey data from the Tokyo Metropolitan Area. The models can be used to estimate truck traffic flows associated with transshipments. The urban portion of the logistics chains was categorized into five types of movements, and 30 models were developed to analyze six commodity groups separately. The results indicated that the proposed approach could capture the mechanism of the selection of a logistics facility by movement and commodity type. The tests for the reproducibility of the models warrant the future use of the models for analysis of urban freight demand.
In the existing freight models, the choices of logistics facility locations and the selection of ... more In the existing freight models, the choices of logistics facility locations and the selection of logistics facilities for routing the shipments are often treated without distinction although these two decisions are distinct and affected by different set of factors in reality. In this paper, we develop models of logistics facility choice that match truck trip ends with logistics facilities using a large urban freight survey data from the Tokyo Metropolitan Area. The models can be used to estimate truck traffic flows associated with transshipments. We categorize the urban portion of logistics chains into five types of movements and develop a total of 30 models to separately analyze six commodity groups. The results indicate that the proposed approach can capture the mechanism of the logistics facility selection by movement and commodity types. The tests for the reproducibility of the models warrant the future use of the models for urban freight demand analysis.
Journal of Transport Geography, 2017
We use the comprehensive freight survey data from 2003 and 2013 to analyze how the restructuring ... more We use the comprehensive freight survey data from 2003 and 2013 to analyze how the restructuring of logistics industry that occurred amid the broad trend of decentralization in the Tokyo Metropolitan Area has affected the efficiency of truck shipments. The analysis reveals that the negative effects of the outward migration of logistics facilities were offset by the increase in average shipment load and efficient spatial distribution of logistics facilities that occurred in parallel with the decentralization. As a result, the truck shipment efficiency improved by 4%.
We use the comprehensive freight survey data from 2003 and 2013 to analyze how the restructuring ... more We use the comprehensive freight survey data from 2003 and 2013 to analyze how the restructuring of logistics industry that occurred amid the broad trend of decentralization in the Tokyo Metropolitan Area have affected the efficiency of truck shipments. The analysis reveals that the negative effects of the outward migration of logistics facilities were offset by the increase in average shipment load and efficient spatial distribution of logistics facilities that occurred in parallel with the decentralization. As a result, the truck shipment efficiency improved by 4%.
Journal of Japan Society of Civil Engineers, Ser. D3 (Infrastructure Planning and Management), 2015
In this paper, we develop location choice models for logistics facilities, applying the framework... more In this paper, we develop location choice models for logistics facilities, applying the framework of the discrete choice model. We use the models to test land-use policies that are designed to decrease overall truck travel. The data from the 5th Tokyo Metropolitan Freight Survey, a large comprehensive urban freight survey conducted during 2013-2014, are used for estimating the models. The models show heterogeneity in the factors for location choice by facility size and suggest a strong influence of shipping origins and destinations for each facility’s choice of location, compared with general accessibility indicators. While still preliminary, these findings indicate that logistics land-use policies need to take into account specific needs of the target group(s) of logistics facilities. We also conduct simulations to evaluate the impacts of different zoning scenarios. The early result indicates that zoning regulation is more influential to larger facilities, but the scale of the impact is modest compared to the deviations of random effects. The findings underscore the complexity of reducing truck travel through land-use policies.
Journal of Transport Geography 46 (2015) 10–19, May 5, 2015
This study uses data from a large-scale freight survey conducted in the Tokyo Metropolitan Area t... more This study uses data from a large-scale freight survey conducted in the Tokyo Metropolitan Area to jointly analyze the spatial distribution of logistics facilities and their proximities to the locations of shipment origins and destinations. The aim of the study is to examine in detail the argument that logistics sprawls increase truck trip distances, and thus would incur negative impacts to the society. We found that between 1980 and 2003, logistics facilities in the Tokyo Metropolitan Area have migrated outward, albeit in a much smaller scale than the cases documented in some U.S. and European cities. Our analysis of the shipment data confirms that logistics sprawl increases truck travel. Furthermore, we found that, regardless of their age, logistics facilities tend to increase shipping distances as their distances to the urban center increase, due to the spatial mismatch between the locations of the facilities and the shipment origins and destinations. The findings underscore the importance of comprehensive efforts to coordinate land use, not only for logistics facilities but also other businesses that generate freight movements.
In the Proceedings of the 94th Annual Meeting of the Transportation Research Board. Washington D.C.
In this paper, we analyze data from a large-scale survey, the 2003 Tokyo Metropolitan Freight Sur... more In this paper, we analyze data from a large-scale survey, the 2003 Tokyo Metropolitan Freight Survey (TMFS), to examine some of the sampling issues associated with urban freight surveys. The TMFS data indicate that the variables commonly obtained from freight surveys, such as tons shipped and truck trips generated at a facility level, have highly skewed population distributions, making it difficult to obtain accurate estimates when the sample size is modest. Using bootstrap method, we compared the performances of stratified sampling against simple random sampling. The analysis indicates that, under the ideal condition, stratified sampling with Neyman allocation can improve the accuracies of the estimates. However, two-phase sampling, which is often used in practice to obtain the information that is necessary to implement the Neyman allocation, tends to produce poor results. The findings presented in this study underscore the importance of sample size in freight surveys and the efforts to capture mega shippers in freight surveys.
Doboku Gakkai Ronbunshuu D, May 2009
Abstract; Sick house syndrome (SHS) is characterized by damage to health caused by the indoor env... more Abstract; Sick house syndrome (SHS) is characterized by damage to health caused by the indoor environment of a building. Although SHS is recognized by the public, there is no medical definition of SHS and the concept of the illness is ambiguous. In order to ...
Thesis Chapters by Takanori Sakai
ii iii ACKNOWLEDGEMENTS I would like to acknowledge that I could not have completed this disserta... more ii iii ACKNOWLEDGEMENTS I would like to acknowledge that I could not have completed this dissertation research without the thoughtful and kind supports of many people, including faculty members, senior researchers, friends and family. I am profoundly grateful to my academic advisor and dissertation committee chair, Professor Kazuya Kawamura. I believe my studies at the PhD program were never as meaningful as they actually are without having Kazuya as my advisor. Kazuya is extremely knowledgeable and insightful and his advices and comments always hit the nail on the head. To discuss with Kazuya about research issues is exciting and inspiring. In addition to his intellectual supports, he seriously cared about my future success as a researcher and offered me a lot of opportunities to work with other researchers and to publicize myself. I appreciate the supports of the dissertation and preliminary committee members. Prof. Mohammadian, Prof. Derrible and Dr. Auld provided me beneficial comments and advices on the model specifications. I really enjoyed the constructive discussions on how to improve the models and expand them for the broader scope. Prof. Tilahun also gave me valuable advices on modeling.
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Papers by Takanori Sakai
Thesis Chapters by Takanori Sakai