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Transportation General Concepts

Transportation General Concepts. Lecture 15 ESD.260 Fall 2003. Caplice. Transportation Operations. Direct operations (DO) Taxi TL Unit trains Charter/private planes Tramp services Courier. Consolidated operations (CO) Bus/rail transit LTL Rail Airlines

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Transportation General Concepts

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  1. Transportation General Concepts Lecture 15 ESD.260 Fall 2003 Caplice

  2. Transportation Operations Direct operations (DO) • Taxi • TL • Unit trains • Charter/private planes • Tramp services • Courier Consolidated operations (CO) • Bus/rail transit • LTL • Rail • Airlines • Ocean carriers/liner service • Package delivery DO conveyances on CO carriers (sub-consolidation) • Rail cars • Ocean containers • Air “igloos”

  3. Core Transportation Activities

  4. Types of Transportation Systems • Based on Consolidation Used • w/o TranshipmentPoint • One to One • One to Many • Many to One • Many to Many • With TranshipmentPoint • One to Many • Many to One • Many to Many • Other Issues • Dynamic TranshipmentPoints • Interleavenedtrips • Planning versus Execution

  5. Solutions Approach • Math Programming Approach • Develop detailed objective function and constraints • Requires substantial data • Solve MILP to optimality • Simulation Approach • Develop detailed rules and relationships • Simulate the expected demand patterns • Observe results and rank different scenarios • Continuous Approximation Approach • Develop a Logistics Cost Function (LCF) that incorporates the relevant decision variables • Obtain reasonable results with as little information as possiblein order to gain insights • Detailed data can actually make the optimization process harder

  6. Time Space Diagram

  7. Cumulative Count Curve

  8. Logistics Cost Function Nomenclature D = Annual demand (items/time) Cr = Rent cost ($/item-time) Ci = Inventory cost ($/item-time) Cf = Fixed transport cost ($/shipment) Cv = Variable transport cost (#/item) HMAX = Maximum headway (time) V = Shipment size (items) V = Total number of units shipped=Σv vMAX = Maximum capacity for transport mode (items) Cs = Fixed cost per stop ($/stop) Cd = Cost per distance ($/distance) Cvd = Marginal cost per item per distance Cvs = Marginal cost per item per stop Ns = Number of deliverystops Cvh = Variable handling costs ($/item) Cfh = Fixed handling costs ($/pallet) vhMAX = Maximum capacity for pallet or box (items)

  9. Holding Costs = R + I

  10. Move Costs = T + H

  11. Transport Costs

  12. Transport Costs • Relation to Capacity • ft(V) is sub-additive: ft(V1+V2)≤ ft(V1)+ft(V2) • CvVMAX<<Cf

  13. Transport Costs • Multiple Modes

  14. Handling Costs

  15. Total Logistics Cost Function

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