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Optimization Models for Long-haul Freight Transportation

Optimization Models for Long-haul Freight Transportation. Teodor Gabriel Crainic Dept. Management and Technology Université du Québec à Montréal and Centre for Research on Transportation Université de Montréal/H.E.C./Poly theo@crt.umontreal.ca 2000. Economic and legal environment.

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Optimization Models for Long-haul Freight Transportation

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  1. Optimization ModelsforLong-haul Freight Transportation Teodor Gabriel Crainic Dept. Management and Technology Université du Québec à Montréal and Centre for Research on Transportation Université de Montréal/H.E.C./Poly theo@crt.umontreal.ca 2000

  2. Economic and legal environment Transportation Systems Physical (Conceptual) Infrastructure and Services Production, Consumptionof Goods and Services SUPPLY DEMAND Movements of people, goods, vehicles = TrafficCosts/profits, delays, energy, emissions, …

  3. Transportation Systems Physical (Conceptual) Infrastructure and Services Production, Consumptionof Products and Services SUPPLY DEMAND Economic and legal environment Movements of people, goods, vehicles = TrafficCosts/profits, delays, energy, emissions, …

  4. Transportation Systems Physical (Conceptual) Infrastructure and Services Production, Consumptionof Products and Services • Modes and Services • Stations and Terminals • Vehicles and Convoys • Routes and Frequencies • Costs and Tariffs • Economic Criteria • Service Quality Criteria • Mode Choice Multimodal Multicommodity FlowsPerformance measures

  5. Transportation Systems • Passengers vs. Freight • User/Shipper vs. Carrier • Urban vs. Interurban/“Regional” • Uni- vs. Multi/Inter-modal • Integration ? • Intelligent Transportation Systems - ITS

  6. Passenger Transportation • Customized (door-to-door) services: private cars, walking, other modes vs.Consolidation transportation: transit • Urban • Multimodal • Short planning horizons (hours) dependent upon time-of-day, day-of-week, week-of-year, … • “authorities plan, users decide”

  7. Freight Transportation • Producers who own or operate the transportation fleet (and infrastructure) vs.“For hire” carriers • Long-haul (intercity) transportation vs.“Local” vehicle routing and distribution • Multimodal transportation system of a region vs. Carrier network and services • Consolidationtransportation vs.Customized(door-to-door)services

  8. b d 2 e c 1 3 f a 4 A 5 B 6 7 C Main route Feeder route 9 8 Pick up and delivery route

  9. Freight Transportation • Many more actors/deciders/issues • Variable planning horizons • Products • Terminals

  10. Planning Levels • Strategic • Long-term • Designs the system structure • Tactic • Medium-term • Designs the service structure • Operational • Time-dependent • Makes happen: dynamic management and control of resources, routes, schedules, ...

  11. Strategic System Analysis and Planning • International, national, regional planning • All (most) products • All (most) transportation modes (infrastructure networks and services) • Scenario analysis (“what if ?”) • Infrastructure modifications • Evolution of demand • Technology changes • Variations in policy and economic environment • …

  12. Methodological Approaches • Spatial price equilibrium • Route/mode choice/loading • Network optimization • Sequential shipper-carrier • System-wide representation

  13. System-wide Modelling • Zones: origins and destination of freight • Modes: transportation means/services • Nodes and modal links • Intermodal transfers • Products: commodity groups • Demand: origin-destination matrices by product (and mode choice) • Output:product flows and costs on links (modes), transfers, and paths

  14. Model Nonlinear (convex) multimode multicommodity network flow formulation

  15. Technological Transfer • Computer-based decision support systems • Custom-made vs. “tool box” • Example: STAN, Strategic Transportation Analysis, software for multimodal, multiproduct transportation systems

  16. Consolidation Transportation • Long distance freight carriers • One vehicle/convoy serves many customers • Railways • Less-than-truckload motor carriers • Intermodal container transportation • Express package services • Control agencies, ...

  17. Consolidation Transportation • Accounts for a huge proportion of the freight moved both in volume and value • Vital component of transportation and economic systems • Less studied • (compare to VRP, location, pure design) • Fewer, more “remote” players • Messier problems and formulations

  18. b d 2 e c 1 3 f a 4 A 5 B 6 7 C Main route Feeder route 9 8 Pick up and delivery route

  19. Consolidation TransportationCharacteristics • Regular services • Consolidation terminals • Frequencies and Schedules • Operation efficiency = profits • Service quality = customer satisfaction

  20. terminal A terminal C terminal D terminal E terminal F terminal B Physical Network Mode 1 Mode 2 SERVICE: - origin terminal - destination terminal - mode - frequency

  21. terminal A terminal B terminal C terminal D terminal E terminal F Physical and Service Networks (B, F) (B, F) (A, E) (B, F) ITINERARY: Path of services used to move freight from its origin to its final destination

  22. + + + (A, E) (A, E) (A, E) terminal B terminal E terminal F terminal C terminal A terminal D Itineraries (B, F) Freight consolidation and (B, F) (A, E) (B, F) Trade-offs: Operating costs minimisation vs. service quality maximization BEST SERVICE AT MINIMUM COST

  23. 490 590 340 440 740 690 390 640 540 60 40 10 90 20 70 30 50 80 Cost vs. Service Trade-offs transportation and handling costs 87% Firm 42% 624000$ (in 1000$) M 73% 440000$ 345000$ Number of markets satisfying the service targets (%) 290 0

  24. Carrier Tactical Planning • Goal: optimal allocation and utilisation of resources to achieve the economic and customer service objectives of the company • Means: tactical plan(load, transportation, … plan) • Evaluation tool of strategic alternatives

  25. Carrier Tactical Planning • Interrelated decisions • Service selection:routes, frequencies, schedules • Traffic distribution:itineraries, flow distribution • Terminal policies • Empty balancing • Interactions and trade-offs • Among operations • Between cost and service quality (time) measures

  26. Tactical planning issues for freight carriers generally addressed through Service Network Design formulations and methods

  27. Service Network Design • It’s planning => Network view • Planning horizon • Strategic/Tactical • Tactical/Operational • Generally several interacting resources • Usually several interacting objectives • Certainly many “decisions” • Static or dynamic (deterministic) formulations

  28. Service Network Design:Model Classes • Location • Frequency • Schedules/Dispatching (Dynamic)

  29. Location Design • Strategic “long term” design of infrastructure considering impact on services and traffic • Location of terminals • Location-routing • Not many models specific for long-haul consolidation freight transportation • Deterministic service network design models used to simulate scenarios

  30. Location Design • A few discrete locationmodels • Production-distribution • Hub-network design • Multicommodity location-allocation with balancing requirements

  31. Loaded container Empty container A Container Land Distribution and Transportation System Empty vehicle

  32. Location with Balancing • Locate depots to optimize the distribution and transportation of empty containers • Movements • Customer to depot: return movement • Depot to customer: allocation following request • Between depots: to counter supply-demand imbalances and reposition for future periods

  33. supply Network Structure customers j k depots customers demand (flows of empty containers)

  34. supply Network Structure customers j k depots customers demand (flows of empty containers)

  35. Location With Balancing Formulation

  36. Location with Balancing Formulation

  37. Frequency Service Network Design • Objectives • Strategic planning and scenario analysis • Study of interactions and trade-offs among subsystems, decisions, objectives • Typical issues • Whattype of service? • Howoften over the planning horizon? • Terminal workloads • Traffic itineraries (includes empties)

  38. Two Major Approaches • Service levels as Decisions • Service levels as Output

  39. Service Frequencies: Decisions • Integer frequencies • Continuous flows • Nonlinear Mixed Integer formulations: frequency-related measures (costs, delays-congestion, etc.) • Physical network: given infrastructure • Service network: decision structure • Traffic itineraries: on service network

  40. A1 F1 A2 F2 A3 F3 A3 A4 A4 A4 A4 A2 A2 C C C C C T S X4 X2 X1 X3 PHYSICAL NETWORK (NODES, LINKS) A4 SERVICE LEG F4 SERVICE NETWORK (ROUTES, STOPS, MODES, FREQUENIES) ITINERARIES FOR A TRAFFIC-CLASS (O-D-C)

  41. Model Elements • Physical network • Nodes: rail yards and stations, LTL breakbulk and end-of-line terminals, ports, … • Links: tracks, roads, … • Capacities and operational rules • Service • Route, type, costs, ... • Frequency

  42. Model Elements • Demand • Market = origin, destination, commodity • Empty vehicles = product(s) • Volume • Costs, service and operational rules • Set of feasible itineraries • Itinerary flows

  43. Model • Minimize • “Fixed” cost of offering service • Costs of moving the freight through the service network • Penalties on unsatisfied service objectives or operational rules and characteristics (e.g., capacities) • Subject to • Demand satisfaction • Service and operation constraints

  44. Service Frequencies as Decision Variables Minimize Subject to and integer Specific service and operation constraints

  45. Service Cost • Determined by system characteristics and (potentially) all other services • Cost of operations in terminals and en-route • Cost of time (average delay) spent in terminals and en-route

  46. Itinerary Cost • Determined by system characteristics and (potentially) all services and itinerary flows for all markets • Cost of operations in terminals and en-route • Cost of time (delay) spent in terminals and en-route

  47. Itinerary Cost • Capacity considerations on service segments • Compliance with service targets

  48. Delays - A Few Examples • Rail yard operations: car classification and blocking, train formation, … • Consolidation of freight in vehicles • Waiting at terminal “gates” before admission • Train delays due to meetings and overtakes on the lines of the network. • Departure/connection delays in terminals: the waiting time for the designated service to be available

  49. Delays • Representation: Congestion functions • Models: Engineering procedures + queuing models

  50. Dynamic Service Network Design • Objectives • Planning of “schedules” • Ifor when services depart • Traffic itineraries • Space-time graphs

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