U.S. Ethanol: Evolving Supply Chain and Rail-Truck Competition
Elvis Ndembe, North Dakota State UniversityShow Abstract View Presentation
This paper examines the relationship between corn ethanol and modal competition for local freight transportation. Ethanol plants provide an alternative market to sell and ship corn locally where traffic is widely viewed as truck-dominant. A derived demand model is estimated using a sample of quarterly corn shipment data to the 10th largest ethanol plant by capacity in U.S from 2013 to 2016. Overall, results at the means of all variables show truck traffic dominance based on the modal dominance rule used in this paper. However, average input demand elasticities indicate that truck does not dominate for the entire range of corn tonnage shipped. Generally, rail demand becomes less elastic and truck demand becomes more elastic with higher tonnage. Results point to the potential for rail to compete in local freight markets thought to be truck dominated. Another explanation for results is likely economies of shipment size in local freight markets.
An Integrated Solution for Location-Inventory-Routing Problem of Fresh Products with Environmental Consideration
Liying Song, Beijing Jiaotong UniversityShow Abstract View Presentation
Handong Li, Beijing Jiaotong University
The market of fresh food products is under amazing developments in China. How to maintain the freshness of the food products is a big challenge to the supply chain management. In addition, with the increased concern in the environment imparts from the logistics operation, many measurements have been implementd to reduce the carbon emssions from three key operations in the supply chain, i.e., inventory, location and routing. The research aims to quantify the operational costs of the fresh food product supply chain, and calculate the carbon emissions incurred in the chain. Mathematical formulations of the proposed location-inventory-routing problem are set up, with objectives of minimizing monetary cost, carbon emission and overall costs, respectively. Cargo loss rate and carbon tax rate are incorprated in the models, and an improved simulated annealing (SA) algorithm is designed to solve the models. The computational results will be helpful in identifying the operational strategy of minimizing the costs while considering the environmental impacts. It is interesting to find that proper carbon price can simutaneouly reduce the operational cocts while reduce the carbon emissions in the supply chain.
Agricultural Product Harvest Equilibrium Under Bottleneck Capacity and Random Disasters
Jia Yao, Harbin Institute of TechnologyShow Abstract View Presentation
Shi An, Harbin Institute of Technology
In this paper, the agricultural product harvest equilibrium models with bottleneck capacity are proposed for the first time. The value of the harvested product is assumed to be a non-negative, continuous, differentiable and strictly concave function with respect to harvest time, which is monotonically increasing/decreasing before/after the best harvest time, respectively. The queuing cost per unit product is assumed to be a continuous linear increasing function with respect to the queuing time. After that, how the random nature disasters affect the harvest equilibrium is also formulated. The sufficient and necessary conditions, making the harvest equilibrium status, satisfy first-come first-service (FCFS) and some other specific features are proved strictly. For comparison, the related optimal harvest schedules are also derived. Finally, a numerical example is used to illustrate the effectiveness of the proposed models and the sensitivity analysis of the related parameters and their potential applications are also performed.
E-Grocery Home Delivery Impacts on Food Access and Equity: A Portland Case Study
Katherine Keeling, Portland State UniversityShow Abstract
Miguel Figliozzi, Portland State University
The adoption of e-grocery home delivery (HD) has the potential to change social norms of acquiring household foods and necessities. In light of recent interest in food deserts, a case study of Portland, OR reviews the new elements of inclusion, exclusion, and value created by the service of four major e-grocery businesses: Shipt, Instacart, Walmart, and Amazon Prime Now. These e-grocers are reviewed in terms of service areas, pricing, and inventory choice, as these are key factors on consumer experience. An equity matrix developed by the City of Portland is also applied. It is important to note that e-grocery service areas are rapidly changing, however a July 2019 coverage analysis found that at least 94% of residents in the Portland metropolitan statistical area have access to HD from at least one retailer. A total of 22 census tracts identified as low-income, low-access (LILA) by the USDA which house 91% of the LILA population in the region were included in an e-grocery HD service area. E-grocery home delivery is discussed with attention to vulnerable population groups that may experience barriers to adoption, as well as vulnerable populations that may benefit. Additionally, we discuss ancillary issues such as the challenges faced by delivery drivers.
Data-Driven Study on the Log Movements for the Upper Midwest: Impact of Rail Car Fleet Size on Freight Storage and Car Idling
Sangpil Ko, Korea Railroad Research InstituteShow Abstract View Presentation
Pasi Lautala, Michigan Technological University
Kuilin Zhang, Michigan Technological University
Rail car availability and challenges with the seasonal dynamics of log movements have received growing attentions in the Lake Superior region, as portion of rail car fleet is close to reaching its service life. This paper proposes a data-driven study on the rail car peaking issue to explore the fleet of rail cars dedicatedly used for the log movements in the region, and to evaluate how the number of cars affects the storage need at the sidings and the time the cars are idled. This study is based on the actual log scale data collected from a group of forest companies in cooperation with the Lake State Shippers Association (LSSA). The results of our analysis revealed that moving the current log volumes in the region would require approximately 400-600 dedicated and shared log cars in ideal conditions, depending on the specific month. While the higher fleet size could move the logs as they arrive to the siding, the lower end would nearly eliminate the idling of rail cars and enable stable volumes throughout the year. However, it would require short-term storage and additional handling of logs at the siding, both elements that increase the costs for shippers. Another interesting observation was the fact that the reduction of a single day in loading/unloading process (2.5 to 1.5 days), would eliminate almost 100 cars (20%) of the fleet without reduction in throughput.