optimizing the aerodynamic efficiency of intermodal freight trains

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Optimizing the Aerodynamic Efficiency of Intermodal Freight Trains. Yung-Cheng Lai Chris Barkan Hayri nal University of Illinois at Urbana - Champaign November 13, 2005. As of 2004, fuel costs had increased by more than 88% since 1998. ~. Average Cost Per Gallon (Cents). ?. - PowerPoint PPT Presentation

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  • Optimizing the Aerodynamic Efficiency of Intermodal Freight TrainsYung-Cheng LaiChris BarkanHayri nalUniversity of Illinois at Urbana - Champaign November 13, 2005

  • As of 2004, fuel costs had increased by more than 88% since 1998Average Cost Per Gallon(Cents)?~

  • Intermodal (IM) trains incur greater aerodynamic penalties and fuel consumption than general trainsIM trains suffer from their equipment design and loading pattern

    IM trains are the fastest freight trains operated in North America

    Investigation of options to improve IM train fuel efficiency have the potential to reduce fuel costs

  • Loads should be assigned not only based on slot utilization but also slot efficiencyMaximizing slot utilization improves train efficiency since it eliminates empty slots and the consequent large gapsHowever, two trains may have identical slot utilization, but different loading patterns and aerodynamic resistanceLoads should be assigned not only based on slot utilization but also better matching of loads with cars (slot efficiency)Train resistance could be lowered by as much as 27% and fuel savings by as much as 1 gallon/mile/train40404040405353535353

  • A machine vision system has been developed to monitor the slot efficiency of intermodal trains

  • Frequency diagram is used to evaluate the aerodynamic efficiency of IM trains

    How can we further assist railroads in fuel savings?

  • A model to automatically assign loads to the train ensuring minimum fuel consumption is neededLoading assignment at intermodal terminals is still a largely manual process

    Containers or trailers are assigned to available well, spine or flat cars following weight and length constraints

    We treat the train make-up as given because cars in an IM train generally are not switched

  • We present an IP model and a heuristic approach that incorporate IM train aerodynamicsIntermodal train aerodynamicsModels for optimal loading:Integer programming (IP)Heuristic methodComparison of IP and heuristic results

  • Gap Length and Position in Train are the two most important factors to IM train aerodynamics

    Based on the wind tunnel testing of rail equipment, three important factors to IM train aerodynamics were identified: 1. Gap Length between the IM loads 2. Position in Train 3. Yaw Angle: wind direction (canceled out over the whole route)

  • Larger gaps resulting in a higher aerodynamic coefficient and greater resistance

    Chart2

    0.0285

    0.0301

    0.0326

    0.0357

    0.0395

    0.0416

    0.0439

    0.0458

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    0.0458

    Gap Length (ft)

    Aerodynamic Coefficient (lbs/mph/mph)

    TS

    TRAILERS ON SPINE CAR

    Change Car Length

    Gap LengthC

    10.0329

    20.0354

    30.0396

    40.0463

    50.0568

    60.0727

    70.0802

    80.0851

    90.0882

    100.0894

    110.0888

    120.0884

    130.0892

    140.0901

    150.0910

    160.0919

    170.0927

    Change Trailer Length

    Gap LengthC

    10.0330

    20.0354

    30.0396

    40.0463

    50.0568

    60.0728

    70.0804

    80.0854

    90.0886

    100.0899

    110.0893

    120.0890

    130.0900

    140.0908

    150.0917

    160.0926

    170.0934

    CONTAINERS ON SPINE CAR

    Change Trailer Length

    Gap LengthC

    10.0167

    20.0183

    30.0206

    40.0242

    50.0295

    60.0373

    70.0413

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    90.0458

    100.0469

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    120.0473

    130.0482

    140.0491

    150.0500

    160.0508

    170.0517

    TS

    0.0329

    0.03543

    0.0396

    0.0463

    0.0568

    0.0727

    0.0802

    0.0851

    0.0882

    0.0894

    0.0888

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    0.0919

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    Gap Length (ft)

    Aerodynamic Coefficient

    DSW

    0.033

    0.0354

    0.0396

    0.0463

    0.0568

    0.0728

    0.0804

    0.0854

    0.0886

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    0.0893

    0.089

    0.09

    0.0908

    0.0917

    0.0926

    0.0934

    Gap Length (ft)

    Aerodynamic Coefficient

    Sheet3

    0.0167

    0.0183

    0.0206

    0.0242

    0.0295

    0.0373

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    0.0491

    0.05

    0.0508

    0.0517

    Gap Length (ft)

    Aerodynamic Coefficient

    DS CONTAINERS ON WELL CAR

    Change Cont. Length

    Gap Length

    10.0285

    30.0301

    50.0326

    70.0357

    90.0395

    100.0416

    110.0439

    120.0458

    130.0458

    150.0458

    200.0458

    0

    0

    0

    0

    0

    0

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    0

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    0

    0

    Gap Length (ft)

    Aerodynamic Coefficient (lbs/mph/mph)

  • The front of the train experiences the greatest aerodynamic resistanceObjective: Minimize the total adjusted gap length within the train (adjusted gap length = adjusted factor x gap length )Placing loads with shorter gaps in the frontal position generates less aerodynamic resistance

  • We present an IP model and a heuristic approach that incorporate IM train aerodynamicsIntermodal train aerodynamicsModels for optimal loading:Integer programming (IP)Heuristic methodComparison of IP and heuristic results

  • Minimize the total adjusted gap length within the train

    Where: i= Type of the Load (40, 48, 53 etc.)j= Load Number within the Specific TypeP= Position in the Unit (P1 or P2)k= Unit Number (1,2,,N)Ak= Adjusted Factor of kth GapUk= Length of kth UnitLi= Length of ith Type Load (ft)yijkl= 1 if jth Load in i Type was Assigned to kth Unit Lth Position; 0 otherwise

  • Loading assignment must follow loading capability of each unit as well as length & weight constraintsSubject to:

    Where: Ripk= Loading Capabilitywij= Weight of jth Load in i TypeCk= Weight Limit of kth Unit Qkp= Length limit of position p in kth Unitk= 1 for well-car unit; 0 otherwise = an arbitrarily specified large numberxk= 1 if the top slot of kth Unit can be used; 0 otherwise

  • Load the train sequentially by selecting the best load in the pool for the current unloaded slot The position-in-train effect is automatically accounted for because the train is loaded sequentially from front to back

  • We present an IP model and a heuristic approach that incorporate IM train aerodynamicsIntermodal train aerodynamicsModels for optimal loading:Integer programming (IP)Heuristic methodComparison of IP and heuristic results

  • Applying both methods to a train w/o well cars result in the same optimal loading patternLoads: fifty , fifty , fifty

    Train: ten 5-unit 53-foot-slot spine cars followed by ten 5-unit 48-foot-slot spine cars

    Optimum based on IP & heuristics = 514 (ft)

    Worst case by manual assignment = 1170 (ft)

    Fuel savings is 0.95 gallons/mile/train150 loads100 slots

  • Applying both methods to a train with well cars result in different loading patternsLoads: fifty , fifty , fifty containers

    Train: ten 5-unit 48-foot-slot well cars and

    ten 5-unit 53-foot-slot spine cars

    IP result = 637 (ft)

    Heuristic result = 1096 (ft)

  • In summary, both IP & heuristics methods are better than the current manual assignmentIP approach guarantees the best fuel efficiency, whereas the heuristics produces good but often sub-optimumThere is a 20.6% difference in adjusted gap length between IP & heuristics based on 100 simulation runsCompared to the worst case by manual assignment, the potential fuel savings can be 0.95 gal/mile/train Extrapolating the savings over BNSF transcon would be at least 1,500 gal/train

  • The IP model can be extended to optimize the aerodynamic efficiency at the system levelIn this study, we focus on optimization of the aerodynamic efficiency of one outgoing train for a given set of loads

    Optimizing the daily/weekly loading plan would be beneficial for further increasing the fuel efficiency of the operation

    The complete model is intended to be incorporated into the terminal operation software in the futureQuestions?

    This slide template is for the title slide of a presentation. Consider repeating a key image from one of the slides later in the presentation. The image helps orient the audience to the key words in the title. This image also gives you the opportunity to say a few things about your workperhaps addressing the works importance or providing key background information. Forcing yourself to spend more time with this slide is good because a common mistake in presentations is not to leave the title slide on long enough. Because of this mistake, many in the audience do not have the chance to comprehend the key details of the title. See pages 66, 69-71, and 177 of The Craft of Scientific Presentations (CSP).

    This template shows one layout for the slide. You might want to rearrange the placement of the bodys wording to accommodate a different sized image. The principal metric used to measure the efficiency of loading is slot utilization. Its a metric used to measure the percentage of the spaces on intermodal cars that are used for loads. For example, the top diagram represents 100 % slot utilization since all the slots are filled with containers. The bottom diagram shows 80 % slot utilization. Maximizing slot utilization improves train energy efficiency because it eliminates empty slots and the consequent large gapsHowever, it does not account for the size of the space compared to the size of the loadFrom these diagram, we can see that two trains have i