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Transportation General Concepts

This lecture delves into transportation operations, focusing on direct operations (DO) like taxis, unit trains, and charter planes, as well as consolidated operations (CO) including bus and rail transit, airlines, and ocean carriers. It discusses various transportation systems based on consolidation without transshipment points, and reviews complex logistical challenges such as dynamic transshipment points, planning versus execution, and optimization methods using mathematical programming and simulation. Key factors in logistics cost functions are also examined to provide insights into efficient transportation planning.

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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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