Solving Linehaul Planning Problems for Less-than-Truckload Carriers

Transcription

1 Solving Linehaul Planning Problems for Less-than-Truckload Carriers Ravindra K. Ahuja University of Florida & Innovative Scheduling -1-

2 Two Types of Truckload Companies Full Truckload Networks: Suited for moving large volumes (such as, unit trains). Less-than-Truckload (LTL) Networks: Suited for moving small volumes (such as, Merchandize trains). LTL companies consolidate small volumes of freight from several customers and create full truck loads through a hub and spoke network. -2-

3 Less-Than-Truckload (LTL) Scheduling Problem An LTL carrier receives a set of origin-destination shipments to be carried over its truckline network. Shipment volumes are not large enough to justify a full truckload for every shipment. Several shipments need to be consolidated into full truckloads. -3-

4 LTL Carrier: Consolidation of Shipments The LTL carrier consolidates several shipments into full truckloads to reduce the linehaul cost. Some shipments go directly from origins to destinations, while some shipments go through hub (break-bulk) locations where they are reclassified and put into new loads. -4-

5 Less-Than-Truckload Scheduling Less-than-truckload scheduling is very similar to railroad scheduling. Shipments are like Railcars Trailers are like Blocks Tractors are like Trains Local Pickup & Delivery End-of-line Consolidation Hubs Customer End-of-Line Hubs -5-

6 Similarity of Railroads and LTL Trucking Railcars Blocks Trains Block Plan Train Schedule Shipments Trailers Trucks Load Plan Linehaul Schedule Trucking operations are service centric and meeting service at least cost is their objective. -6-

7 Linehaul Planning Problem Network Hub Locations Operating Hours Truck Costs Truck Capacities Shipments Service Commitments Linehaul Planning Problem Load Plan (Blocking Plan) Load Schedule (Train Plan) Shipment Routes Constraints: Load capacity Commitment time Hub capacity Cost Terms: Linehaul cost Hub operating cost Service commit. violation cost -7-

8 Inputs: Network Locations Hubs, Service Centers, Relay, Transfer Operating hours Minimum terminal connection time Capacities Hub capacities Trailer capacities Costs Tractor costs Single/team driver costs Hub operating costs -8-

9 Inputs: Shipment Volumes Average daily shipment volumes between all origin-destination pairs of nodes by day-of-week. -9-

10 Inputs: Service Commitments Service commitment for specified origin-destination (OD) pairs of nodes by day-of-week. -10-

11 Decision Variables 1: Load Plan The Load Plan determines how shipments move over the network from their origins to destinations. This problem is identical to the Blocking Plan problem. Next Via Location Final Destination Current Location Load 1 ABQ ABQ, PHX Current Locations Final Destinations Next Via Location CHI Load 2 ATL ATL, NASH, MIA CHI ABQ, PHX ABQ CHI ATL, NASH, MIA ATL Load 3 BAL BAL CHI BAL BAL -11-

12 Decision Variables 2: Load Schedules Load schedules specify (similar to train schedules): Load origins and destinations Load operating days Load times HOU Load Dep. Time Days in Route Arr. Time Operating Days DFW AUS IND CHI ATL DFW - HOU 19: :30 MTWTF DFW - AUS 16: :00 MTWTFS_ DFW - IND 20: :15 MTWT DFW - CHI 22: :00 MTWTFS_ DFW - ATL 23: :30 MTWTFSS -12-

13 Time-Space Network for Routing Route all shipment on the weekly linehaul time-space network according to the Load Plan and Linehaul Schedule honoring trailer capacities. Jacksonville Atlanta Chicago Shipment Pickups Mon 9 P.M. Mon 8 P.M. Mon Shipment Delivery Shipment Pickups Tue 9 P.M. 3 A.M. Tue 8 P.M. 8 A.M. Tue Shipment Delivery Shipment Pickups Wed 9 P.M. 3 A.M. Wed 8 P.M. 8 A.M. Wed Shipment Delivery Shipment Pickups Thu 9 P.M. 3 A.M. Thu 8 P.M. 8 A.M. Thu Shipment Delivery 3 A.M. Fri 8 A.M. Fri Shipment Delivery -13-

14 Cost Terms Loaded Linehaul Costs (proportional to miles) Empty Costs (5% - 10%) Purchase Transportation Costs (out-sourcing linehaul) Rail Costs Hub Operating Costs Service Error Costs (97% - 99% service) -14-

15 Railroads Trucking Railroads Trucking Railroad Blocking Optimizer + Train Scheduling Optimizer Integrated Blocking/Train Scheduling Optimizer Forthcoming Major Contributions: Fusion of Blocking and Train Scheduling Models Add Service as Objective -15-

16 Linehaul Planning and Execution For a typical LTL carrier on any particular day: 80% of the schedules come from static plan. 20% of the schedules change from one day to another. Linehaul Planning (Static): Blocking and Train Planning Create an LTL carrier s static linehaul plan. Forms the core of day-to-day s linehaul operations. Linehaul Execution (Dynamic): Real-Time Blocking and Train Planning Execute the static linehaul plan. Manage exceptions to the static linehaul plan. Developing a large LTL Carriers Linehaul Planning and Execution Systems. -16-

17 Linehaul Planning Optimizer We decompose linehaul planning problem into two decision problems: Network Shipments Current Load Plan Service Commitments Load Plan Optimizer (Blocking) Linehaul Schedule Optimizer (Train Scheduling) Revised Load Plan Load Schedules Service Routes Meet-Turn Plan Driver Routes -17-

18 Load Plan Optimizer Network Shipments Current Load Plan Service Commitments Load Plan Optimizer (Blocking) Load Plan (Blocking Plan) Number of Daily Loads (Train Plan) Load Routes (Train Plan) Empty Load (Train Balancing) Constraints: Honor trailer capacities Honor services Honor hub handling capacities Objective: Minimize load miles Minimize empty miles Minimize handling cost Minimize service errors -18-

19 Load Schedule Optimizer Load Plan Optimizer Outputs Load Schedule Optimizer (Train Scheduling) Day-of-Week Load Plan Day-of-Week Load Schedule Meet-Pass Plan & Driver Schedule Shipment Routes by Day-of-Week Terminal Workload Chart Constraints: Same as before Objective: Same as before -19-

20 Algorithms for Linehaul Planning Used algorithms for railroad blocking and train scheduling as starting point of algorithm development and several enhancements. Linehaul Plan Optimization Very large scale neighborhood search Neighborhood search (drop/add/replace) Linehaul Schedule Optimization Neighborhood search combined with trip planning on time-space network. -20-

21 Linehaul Planning User Interfaces Multi-scenario system. Store multiple plans and push one plan into production. Multiple users with different privileges Summary reports Maps and charts with drill-down capabilities -21-

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