The geography of freight-related accidents in the era of E-commerce: Evidence from the Los Angeles metropolitan area

Due to the burgeoning demand for freight movement in the era of e-commerce, freight related road safety threats have been growing in both urban and suburban areas, despite the improved general traffic safety over the past decades. The empirical evidence on how freight trucks related crashes are distributed across neighborhoods and correlated to spatially varying factors is, however, highly limited. This article uses data from the Los Angeles region in 2018 to analyze the spatial patterns of freight trucks related traffic crashes and examines the major factors that contribute to those patterns using spatial econometric models. Maps show that freight trucks related crashes are highly associated with major freight generators but less clustered than the overall traffic crashes. Results from the spatial Durbin model indicate that access to freight generators, economic attributes, land uses, road infrastructure, and road network variables all contribute to the spatial distribution of freight trucks related crashes. The findings could help transport planners understand the dynamics of freight trucks related traffic safety and develop operational measures for mitigating the impacts of growing goods movement on local communities.     

A multi-level spatial-temporal model for freight movement: The case of manufactured goods flows on the U.S. highway networks

The spatial production, attraction, and movement of manufactured goods are vital to the economy of a region and country. The U.S. department of transportation also mandates to incorporate continuing and efficient freight movement and infrastructure into statewide and local long range planning. Studies on supply, demand, and transport of manufactured goods by firm, industry, mode, or commodity are vast in the logistics and supply chain literature. However, relatively sparse research is available on aggregated movement or freight on national, state, or local transportation networks. Better understanding and modeling freight movement on highway networks to facilitate local transportation, land use, economic development, and comprehensive planning is at the heart of freight research. Therefore, the major endeavors and novel contributions of this research include a conceptual framework proposed for freight movement research, a multi-level spatial-temporal freight model based upon the social optimum assignment for optimal “from”, “to”, “within”, and “through” freight flows of manufactured goods on the U.S. highway networks, and a set of performance measures designed to reveal states in terms of their competitive advantages in production, attraction, self-sufficiency, or cross-road. The freight flows were first visualized and highlighted by state at the U.S. level, then by county at the state level for Oklahoma, and finally by traffic analysis zone for the Tulsa metropolitan area. The spatial split of freight flows was accomplished through using freight, network, and demographic-economic databases at state, county, and zone scales.     

基于现代物流理念的铁路货运组织改革的思考

铁路货运是物流体系的重要组成部分,也是亟待改进的部分.简要分析现代物流作用和发展趋势,结合现行铁路货运组织存在的问题,从信息系统、管理模式、设施设备、运营机制和人才机制几个方面,探讨基于现代物流理念的铁路货运组织改革,以利于提高铁路货运组织效率和效益.     

Child road safety in the urban environment

The study makes use of an extensive database of child traffic casualties in the city of Salford (United Kingdom), which combines information from both police and hospital admission sources, to examine child road safety in the urban environment. The spatial distribution of casualties was investigated using both statistical and geographic information system (GIS) techniques. Associated factors relating to traffic, physical, socio-economic and activity variables were included in the analysis. The basic geographical unit of study is the enumeration district (ED) and by aggregating these units to form appropriately defined zones, the relative importance of individual factors was identified. At the district level of study, the analysis allowed the impact of differences in traffic flow, land use and road user behaviour to be studied.     

Satellite terminals: a local solution to hub congestion?

Transport hubs are important generators of freight traffic both between and within metropolitan areas. The concentration of traffic places pressure on the terminals to expand their sites to cope with the business. At the same time the spatial spread of flows is becoming more extensive, impacting ever more severely on local communities. This paper explores some of the questions involving the need for terminals to continue expanding sites that are often in zones of intense environmental and land use conflict. It goes on to consider an alternative comprising satellite facilities, with the consequential dispersal of some transfer functions to sites that may be some distance from the main hubs themselves.     

Multi-criteria decision-making for complex bundling configurations in surface transportation of air freight

Airlines typically carry out freight transportation in a hub and spoke structure, where the movements between the outstations and the hub are served by trucks. To transport freight efficiently, air carriers must consider bundling options for shipments that are delivered at outstations and have to be moved to the hub. There are three options when it comes to bundling freight: on ‘through unit load devices’ (T-ULD) (all freight for the same flight at the hub), on ‘mixed unit load devices’ (M-ULD) (freight for different flights at the hub) and loose freight in trucks. The optimal freight bundling configuration for carriers, taking into account their main KPIs (key performance indicators), is unknown. This research formulates the problem as a multi-criteria decision-making (MCDM) problem, allowing carriers to decide which configuration is optimal for a given outstation. The selected KPIs (cost, (un)loading time, and quality) are formulated as mathematical functions. A new MCDM, called best worst method (BWM), is then used to identify the best configuration with respect to the three KPIs. The proposed methodology is applied to KLM Cargo to identify the best configuration for the selected outstations that supply freight to the KLM hub at Schiphol Airport. This case study shows that there are different optimal freight bundling configurations for different outstations and that trucking costs and freight handling tariffs are among the key factors in deciding which configuration is optimal.     

Stopover and hub-and-spoke shipment strategies in less-than-truckload carriers

This paper presents a methodology to identify when freight consolidation strategies are cost-efficient in the less-than-truckload carriers operations. Shipments are assigned based on proximity and cost criteria to build an initial long-haul shipment solution. This initial solution is later improved by the implementation of Tabu Search algorithm. The proximity criterion takes into account the spatial distribution of shipments loads among centers. The results show that the proposed methodology may reduce the transportation cost by 20% compared to the solution of those heuristics only considering cost criterion.     

The end of travel time matrices: Individual travel times in integrated land use/transport models

To reduce inaccuracies due to insufficient spatial resolution of models, it has been suggested to use smaller raster cells instead of larger zones. Increasing the number of zones, however, increases the size of a matrix to store travel times, called skim tables in transport modeling. Those become difficult to create, to store and to read, while most of the origin-destination pairs are calculated and stored but never used. At the same time, such approaches do not solve inaccuracies due to lack of temporal resolution. This paper analyzes the use of personalized travel times at the finest spatial resolution possible (at x/y coordinates) and a detailed temporal resolution for synthetic agents. The approach is tested in the context of an existing integrated land use/transport model (ILUT) where travel times affect, among others, household relocation decisions. In this paper, person-level individual travel times are compared to traditional skim-based travel times to identify the extent of errors caused by spatial and temporal aggregation and how they affect relocation decisions in the model. It was shown that skim-based travel times fail to capture the spatial and temporal variations of travel times available at a microscopic scale of an agent-based ILUT model. Skims may provide acceptable averages for car travel times if a dense network and small zones are used. Transit travel times, however, suffer from temporal and spatial aggregation of skims. When analyzing travel-time-dependent relocation decisions in the land use model, transit captive households tend to react more sensitively to the transit level of service when individual travel times are used. The findings add to the existing literature a quantification of spatial biases in ILUT models and present a novel approach to overcome them. The presented methodology eliminates the impact of the chosen zone system on model results, and thereby, avoids biases caused by the modifiable spatial unit problem.     

A new zone system to analyze the spatial relationships between the built environment and traffic safety

This study aims to investigate the impacts of the built environment on traffic safety at a zonal level using a newly developed crash-related zone system. Traffic analysis zones (TAZs) have been widely employed to analyze traffic safety at a macroscopic level. However, this zone system use may present problems. Unlike previous studies, in which new zoning systems were created from aggregating TAZs, in this study the new zone system, formed by traffic safety analysis zones (TSAZs), is created from the smallest available census units. Geographically Weighted Negative Binomial Regression (GWNBR) models are used and a comparative analysis between non-spatial global crash prediction models and spatial local GWPR (Geographically Weighted Poisson Regression) and GWNBR models using the two zonal systems is presented. We find that TSAZs based models performed better than TAZs based models, especially when combined to the GWNBR technique. Our results show that several features of the built environment are significant crash predictors, and that the relationships among these features and traffic safety vary across space. By combining a crash-related zonal system with spatial GWNBR models to understand the built environment effects on traffic safety, the results of the analysis can help urban planners to consider traffic safety proactively when planning or retrofitting urban areas.     

A multi-criteria analysis framework including environmental and health impacts for evaluating traffic calming measures at the road network level

Recent interests in both vehicle emissions and public health have facilitated the development of more eco-friendly transportation systems. This study developed a multi-criteria evaluation framework to evaluate the effectiveness of traffic calming measures (TCMs) from the various perspectives at the road network level; operational efficiency, traffic safety, environmental and health impacts. The proposed methodology employs four-step sequential simulation experiments, including driving, traffic flow, emissions, and air dispersion simulations. The results obtained from these four simulations are used to evaluate the effectiveness in terms of safety and operational efficiency in addition to environmental and health impacts. A multi-criteria value function based on the weights estimated from the analysis of an analytical hierarchy process (AHP) is applied in the evaluation framework. As an application, chicanes and speed humps widely implemented in Korean school zones were evaluated at the road network level. The proposed simulation-based approach is expected to be effectively used for the decision-making process in selecting better alternatives for TCM.     

Freeway traffic congestion in Riyadh, Saudi Arabia: attitudes and policy implications

The last few years have shown an unprecedented increase in traffic congestion in Riyadh, Saudi Arabia, especially on radial freeways. Unorganized distribution of land uses, inefficient traffic management, and low-cost automobile use have been major contributors to the problem. This article shows a strong awareness amongst drivers of the negative consequences of the congestion problem. Interviewees have strongly supported several land use, traffic management and transportation provision measures to alleviate freeway congestion but have strongly opposed increasing automobile travel costs. The study suggests an integrated approach to reduce the congestion problem through integrated policies for land use, economics and transportation.     

Freight transportation demand elasticities: a geographic multimodal transportation network analysis

This paper presents direct and cross-elasticity estimates of the demands for three freight transportation modes: rail, road and inland waterways. They are computed for 10 different categories of goods with a detailed multimodal network model of Belgian freight transports. The model, which minimises the generalised cost of transportation tasks defined by O-D matrices, assigns traffic flows to the different modes, transport means and routes. Successive simulations with different relative costs permit the computation of specific arc-elasticities. In contrast with the usual methodologies, the present methodology is not based on a statistical analysis of disaggregate data on actual modal choices and transport tariffs. This is a particularly useful feature since such data are mostly not available for freight transports in Europe. Furthermore, it fully takes into account the detailed characteristics of the network, all available routes and combinations of modes, as well as the specific localisation of activities within the network. Its estimates are compared with previously published estimates, and, in particular, with Abdelwahab's results published (1998) in this journal.     

城市交通发展对铁路货运站布局影响的研究

城市区域结构和产业布局的调整、城市规划理念的变化,使铁路货运站的位置需重新确定。城市轨道交通形成网络后,市内运输能力大大提高,铁路枢纽所有为城市服务的设备和设施均可移出市区,城市内的货物运输可由城市轨道交通系统利用凌晨时段完成。为此,提出了铁路枢纽内货运站设置的数量、位置,以及城市内货运集散点位置的确定方法。     

Factors in the sea ports-of-entry and road ports-of-entry cross-border logistics route choice

The increasing demand for foreign trade in inland areas has led to an increasingly prominent problem of competition between land ports-of-entry (POEs) and sea POEs, and it has also made the comparative study of land POEs and sea POEs cross-border logistics necessary. However, the data used in the existing literature are usually based on surveys or small samples, resulting in inaccurate research results, and most studies generally ignore the spatial heterogeneity of shippers who uses cross-border logistics service and individual preference differences. Taking the international trade between China, Myanmar and Vietnam as an example, and considering the geographical spatial characteristics of various factors, we analyze how geographical factors affect the cross-border logistics routes choice. By using the conditional logit model, the influence of geographical factors on the land POEs and sea POEs cross-border logistics routes choice is compared. The results show that there are significant differences in the characteristics and their influencing factors, which are reflected in the scale of freight, transportation distance, duration, transportation expense, infrastructure quality, geographical location and characteristics of the shippers and POEs. The distance equivalent tool is introduced to calculate the competition balance point of the sea/road POE. The impact mechanism of cross-border logistics choice of land POEs and sea POEs cross-border logistics is explored. Finally, according to the spatial differences of POEs, policy suggestions are proposed.     

The geography of air freight: connections to U.S. metropolitan economies

Despite the rapid growth of air freight shipments, much of the existing literature on the geography of air transportation has paid more attention to passenger travel than air freight. The purpose of this paper is to elevate our understanding of air freight by determining which specific variables most influence and shape the geographic distribution of air freight by metropolitan area using stepwise regression analysis. The empirical results suggest a regression model of five independent variables was the most parsimonious solution where the final model accounted for 71.1% of the variation in air freight shipments by metropolitan area (MA). The most important predictor was the traffic shadow effect, where less populated MAs under the traffic shadow of larger MAs tended to generate lower levels of freight. The model also suggested that other key predictors included the employment market share in transportation-shipping-logistics industries, per capita personal income, the number of medical diagnostic and supplier establishments, and above average wages in high technology. Overall, metropolitan markets with diverse and efficient ground support systems, freight forwarders and other transportation services, a more affluent population, an intense agglomeration of medical laboratories and related suppliers, and a well paid skilled workforce engaged in computer systems design and electronic product manufacturing are more likely to ship freight by air.     

Development of zone system for macro-level traffic safety analysis

Various geographic units have been used in macro-level modeling. Amongst these units, traffic analysis zones (TAZs) have been broadly employed in many macroscopic safety studies. Nevertheless, no studies questioned the validity of TAZs for crash analysis at the macro-level crash modeling. In this study, we point out several possible problems of TAZs as spatial units for macroscopic safety studies. Current TAZs with homogenous crash rates were combined into new single zones. Then we created ten new zonal systems by different zone aggregation levels. The optimal zonal scale for traffic safety analysis zones (TSAZ) was determined using the Brown-Forsythe test. It was found that the zone system with about 1:2 aggregation was the optimal zone system for macroscopic safety modeling. Thus we develop what we call traffic safety analysis zones (TSAZs) that has the potential of reducing several possible problems of TAZs. Also it was shown that TSAZ based models had better fit compared to TAZ based models.     

Urban spatial structure,employment subcenters,and freight travel

Metropolitan areas in the U.S. have become increasingly polycentric. Large employment subcenters have emerged outside of central cities, competing against the traditional city center for labor and businesses. The existing literature on land use and transportation focuses on passenger travel, providing little insight into the impact of polycentric metropolitan development patterns on freight activity. In this study, we use the Los Angeles region as a case study to examine the relationship between urban spatial development patterns and freight travel. Using the National Employment Time Series (NETS) data, we identify employment subcenters in metropolitan Los Angeles. We characterize freight activities associated with the subcenters using data from the Southern California Association of Governments (SCAG). We develop a regression model that estimates freight activity as a function of geographic characteristics, such as whether a location is in an employment subcenter, measures of nearby employment, access to the highway network, and proximity to intermodal freight facilities. The results indicate that employment is an important driver of freight activity; however, employment subcenters have an independent effect on freight activity. The results of this study suggest that further research on urban spatial structure and freight activity should assess the effects of employment subcenters and how their particular employment composition and characteristics are associated with freight activities at the metropolitan level. Such an approach would lead to more precise policy recommendations for urban goods movement.     

我国铁路快捷货运产品设计及组织优化的探讨

快运产品设计是铁路快捷货运普遍关注的问题.针对铁路快捷货运产品现状和存在的问题,提出铁路快捷货运业务流程再造的目的、内容和机理.基于流程再造,对快捷货运产品进行完善设计,提出细分和强化既有快运产品,开发诸如多式联运、高速、客车化、运输组织创新的快运新产品.以特快、快速、普快三类快运产品划分为标准,设计运输组织优化步骤,实现以市场为导向的铁路快捷货运产品设计和组织.     

铁路货运高质量发展策略研究

2021年,全路货运系统深入推进运输结构调整,大力实施以货补客,深化货运组织改革,高站位完成重点物资保供任务,高质量完成多式联运发展目标,货运服务质量和信息化水平进一步提升,货运安全管理进一步强化,货运安全局面持续稳定。2022年,全路货运系统要抢抓机遇、担当作为,深入开展货运安全专项整治、强化货运专业管理基础、扩大“公转铁”工作成效、加快集装箱多式联运发展、促进专业物流稳步增量、服务“一带一路”建设,在全面深化基础管理、持续推进运输结构调整、优化“一带一路”铁路运输组织、持续深化货运组织改革、强化队伍建设和监督检查上取得新成效,奋力推动铁路货运高质量发展。     

Built environment and potential job accessibility effects of road pricing: A spatial econometric perspective

This paper analyzes the impacts of the built environment (BE) as it relates to the potential job accessibility (PJA) effects of road pricing. The relationships between the BE elements and PJA under a road charging policy are established using a spatial econometric approach, which uses an integrated land use and transportation model (TRANUS model) and a spatial lag model (SLM). With the intent of further analyzing the differences in the PJA effects of road pricing on traffic analysis zones (TAZs) that contain different combinations of BE elements, a quantitative classification method combining factor and cluster analysis is applied. This will quantitatively categorize TAZs inside and outside the tolled areas. In exploring the relationship between changes in PJA and the road pricing policy, we found the spatial autocorrelation coefficient to be negative. This result suggests that we are unable to increase the PJA of all the regions through road pricing, but rather affect a redistribution of PJA between different regions. Results also indicate that the impacts of road charging on PJA are associated with urban BE elements. Moreover, such effects are the common result of specific characteristics of the BE. The higher the number of jobs, the better the public transportation conditions, and the better the street design (high densities of street and intersections), the less the region will be negatively influenced by a road charging policy, and vice versa. To avoid the negative effects of road pricing on PJA prior to the launch of such a policy, cities should improve public transportation networks and enhance the street design of the road pricing policy areas, especially the toll ring periphery area.