Simulation Applications In Logistics And Transportation

  • 1,398 views
Uploaded on

Discrete Event Simulation Applications in Validating / Designing Logistics & Transportation Network

Discrete Event Simulation Applications in Validating / Designing Logistics & Transportation Network

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
No Downloads

Views

Total Views
1,398
On Slideshare
0
From Embeds
0
Number of Embeds
1

Actions

Shares
Downloads
0
Comments
0
Likes
2

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. Simulation Applications in Logistics & Transportation systems
  • 2. Contents 1. Introduction to Logistics & Transportation Systems 2. Classification of Logistics & Transportation Simulation models 3. Inputs / Outputs of the Simulation Model
  • 3. Introduction
      • Definition : Logistics & Transport (L&T) can be defined as a network composed of one or more terminals / hubs connected by a set of traffic lanes
    • Major elements of L&T system :
    • Direct Resources : Resources used in physical transportation of freight (goods) from one geographical location to another
    • e.g.: Trucks, Aircrafts, Cargo Ships, Drivers, Pilots etc.
    • Indirect Resources : Resources used in sorting, storing, handling, retrieving and consolidating at the various transit locations
    • e.g.: Forklifts, Docks, Carts, Storage-bins and Racks inside warehouse etc.
  • 4.
      • Direct (moving) and Indirect resources must operate together in the most efficient manner for smooth and balanced operation of L&T network. Which would reduce amount of delays at hubs / Maximum availability & utilization of resources / On time pick-up and delivery of physical goods
    • Right Part at the Right Place at the Right Time
  • 5. Classification of Logistics & Transportation Simulation models
  • 6.
    • Simulation models in L&T are built for the following purposes:
      • Models for strategic planning
      • Models for tactical planning
      • Models for network/traffic control:
          • Offline control
      • Models for scheduling and dispatching:
          • Off-line scheduling
          • Exception handling
          • Real-time monitoring
    Classification of simulation models
  • 7.
    • L&T Problems appropriate for simulation studies are divided into three major categories:
      • New design
      • Evaluation of alternative designs
      • Refinement and redesign of existing operations
      • Problems in new design domain are solved generally by optimization / heuristic approaches. Simulation models are often used for validating purposes on case to case basis but not mandatory
    Classification of simulation models
  • 8. A. New Design
      • Network design : validation of Hub/Spoke design and Direct move
      • Terminal / Hub planning :Identifying No. of terminals, Location, Size (dock dimensions, number of doors)
      • Fleet Planning
      • Route Planning
      • Least- cost transportation modes
    Simulation works through an iterative approach and does not generate alternatives as such
  • 9. B. Evaluation of alternative designs
      • Transportation mode alternatives:
        • On-the-road (trucks) – Relay / Sleeper
        • Rail (trains) : Single / Double stacked
        • Air : Planes / Helicopters
        • Ocean : Ship / Barges
      • Inter-modal alternatives:
        • Combine sleeper with rail
        • Combine relay with sleeper
        • Combine rail with relay
        • Combine trucks with air
        • Combines trucks/air with ocean
  • 10.
      • Service performance alternatives:
        • Overnight service
        • Two – day service
        • Premium service
    B. Evaluation of alternative designs
  • 11. C. Refinement and redesign of existing operations
      • Operational performance analysis
      • On-the-road movements
        • Line-haul, regional and group operations
        • Terminal operations
      • Operating rules
        • Hooking, unhooking, hostling and fueling
        • Trailer loading and trailer off-loading
        • Dock operations
        • Dispatching
  • 12.
      • Rail movements:
        • Loading strategies at the rail yard
        • Train timetables
        • Capacity requirements
      • Air transportation:
        • Origin terminal operations
        • End - of- line operations
        • Central / distributed hub operations
    C. Refinement and redesign of existing operations
  • 13. 2. Inputs / Outputs of the Simulation Model
  • 14.
      • Simulation of warehousing and distribution systems
      • Simulation of trucking operations
      • Simulation of truck docks
      • Simulation of ramp operations in air-cargo hubs
    Case Studies Factors to be considered in each of the case studies:
      • Purpose of building the model
      • Entities, resources and critical processes that need special attention
      • What- if scenarios
      • Input data required
      • Output data from simulation
  • 15. 1. Simulation of warehousing and distribution systems
  • 16.
    • Purpose of the simulation model:
    • To evaluate the performance of individual value adding (indirect) resources,facilities and operations as well as the flow of transportation entities (direct resources) between the plants, warehouses and customers.
      • To evaluate strategic decisions
        • Warehouse location and allocation
        • Warehouse / Distribution center designs
        • Transportation mode analysis
      • To test tactical solutions
        • Inventory management policies
        • Pull ordering between customers and plants
        • Push ordering between warehouses
        • Service levels
    Simulation of warehousing and distribution systems
  • 17.
      • To identify operation problems on an ongoing basis
        • Changes in transportation modes
        • Changes in warehouse operation parameters
        • Changes in parts and finished products
        • Customer demand fluctuations
    Simulation of warehousing and distribution systems
  • 18.
    • Entities:
      • Product related entities
        • Primary and non primary parts : Produced in-house / Vendor supplied
      • Products (Semi-finished / Finished )
      • Palletized Items
        • Parts
        • Semi- Finished Products
        • Finished Products
      • Information oriented entities
        • Orders from customers
        • Orders for shortage
    Simulation of warehousing and distribution systems
  • 19. Resources:
      • Trucks
        • Between plants and warehouses
        • Between warehouses
        • Between warehouses and customers
      • Airplanes
        • Between plants and warehouses
        • Between warehouses
        • Between warehouses and customers
    Simulation of warehousing and distribution systems
  • 20.
      • Ships / Barges
        • Between domestic (foreign) plants and foreign (domestic) warehouses
        • Between foreign warehouses
        • Between domestic (foreign) warehouses and foreign (domestic) customers
      • Internal (warehouse / plants / distribution centers / customer sites) equipment
        • Forklifts
        • Carts
        • Pallet Trucks
        • Conveyors
        • AS/RS Systems
        • Guided Vehicles
    Simulation of warehousing and distribution systems
  • 21. Processes / Activities:
      • Order processing at the warehouse (manual ,automated )
          • Pull ordering system
          • Push ordering system
      • Terminal operations at plants, warehouse and customers (domestic/ foreign)
      • Grouping / Palletizing
          • At a production plant before shipping to a warehouse
          • At a warehouse before shipping to a customer
      • Ungrouping
          • At a warehouse once the parts arrive from a plant
      • Transportation mode selection
          • At production plants
          • At warehouses
    Simulation of warehousing and distribution systems
  • 22.
      • Handling shortages (or surplus inventory)
          • Creation at a warehouse (domestic / foreign)
          • Send an order message to another warehouse
      • Movement of parts (raw materials, semi-finished)
          • From domestic plants to domestic warehouses
          • From foreign plants to foreign warehouses
          • From domestic plants to foreign warehouses
          • From foreign plants to domestic warehouses
      • Movement of finished products
          • From domestic warehouse to domestic customers
          • From foreign warehouse to customers abroad
          • Between domestic warehouses
          • Between foreign warehouses
          • Between domestic and foreign warehouses
    Simulation of warehousing and distribution systems
  • 23.
      • Customer orders
          • From foreign customers to domestic warehouses
          • From foreign customers to warehouses abroad
          • From domestic customers to domestic warehouses
      • Transportation mode selection
          • Based on a specified service level
          • Based on the availability of resources
          • Based on shipment priorities
          • Based on customer location
      • Direct shipment from plant to customers
          • In case of Items in shortage
          • Incase of Emergency items
          • OEM Products
    Simulation of warehousing and distribution systems
  • 24. Data requirements (inputs for the simulation model)
      • Number of plants
      • Number and location of warehouses
      • Number of customers
      • Customer demand to warehouses
      • Part number produced at different plants
      • Bill of materials
      • Transportation times
          • Between plants and warehouses
          • Between warehouses and customers
    Simulation of warehousing and distribution systems
  • 25. Simulation Outputs and Responses ( Outputs from the Simulation)
      • Average utilization
          • Warehouse
          • Trucks
          • Airplanes
          • Other resources inside a warehouse
      • Inventory Levels
          • Production plants
          • Warehouses
      • Transportation delays
          • Between the plant and a warehouse
          • Between a warehouse and customers
      • Customer orders
          • Average waiting times at a warehouse
          • Number waiting at a warehouse
    Simulation of warehousing and distribution systems
  • 26. 2. Simulation of trucking operations
  • 27. System Description
      • Freight may be transported directly or via several intermediate terminals
      • LTL (less than truckload) or DL (direct load) mode
      • Straight truck / Tractor – Trailer combination – in latter case one, two or three trailers are hooked to the tractor by hooking persons (hostlers) at the yard in a terminal
      • Truck drivers arrive at the terminal at pre-specified time as per the schedule
      • Number of trailers hooked to a tractor may vary depending on the amount of freight
      • Set number of loaded trailers are transported by relay, by sleeper, by meet-and-turn drivers, or by rail from each terminal, hub or consolidation center
      • Occasionally empty trailers in case of load imbalance – when more freight moves in one direction than in another direction
    Simulation of trucking operations
  • 28.
      • Driver pool is divided into following three types:
          • Pick-up and delivery drivers : who stay within a city zone
          • Relay drivers : who drive trucks from one terminal to the next for a shorter period and return back to the original terminal which is their domicile location
          • Sleeper drivers : where two drivers alternate driving and drive to farther destinations with minimum number of stops for a longer period
      • When a truck driver is at a terminal location that is not his or her domicile point – he is referred to as foreign driver . At the foreign location the drivers will be provided accommodation to rest for a period of time (say 8 to 10 hours) before driving back to the domicile location – as per the schedule. Foreign drivers have higher priority – so as to reduce the cost of managing them
      • Once the drivers return to their domicile location, they go home and wait until their next assignment
    Simulation of trucking operations
  • 29.
      • To reduce the cost of managing drivers when they are at foreign terminals, trucking companies set up a pool of meet-and-turn drivers
      • These drivers are used to exchange trucks from two terminals moving towards each other when the total transport time is within 8 to 10 hours
      • Meet-and-turn drivers at a central point, swap their trucks and turn back to their domicile terminals
      • Meet-and-turn drivers start from a domicile terminal and end up at their domicile location
      • On arrival straight trucks waits at the yard to wait for its turn to offload
      • Tractor- trailer pair – set is unhooked and waits at the yard for offloading, unhooked tractor maybe taken for maintenance checks, refueling etc.
    Simulation of trucking operations
  • 30.
      • Each terminal has a dock with sufficient doors for the loaded trailers or trucks to arrive at a pre-specified door and offload
      • Off-loading may involve use of manual handling or forklifts or other material handling equipment
      • Truck docks are divided into areas specifically for offloading trucks (or trailers) and reloading trucks or trailers
      • Some may have same areas for offloading / reloading to take down the time required for the freight to be staged before it is reloaded for transportation to its final destination
      • Simulations can be applied to several areas of trucking operations as follows :
      • Dock Simulation – modeling and analysis of truck docks
      • Terminal Simulation – modeling and analysis of activities taking place inside a terminal
      • Line-haul Simulation - combines dock operations and terminal operations network, more complex
    Simulation of trucking operations
  • 31.
    • Simulation model is built to address a variety of problems such as :
          • Current methods of hooking trailers
          • Current procedures used to assign drivers to schedules
          • Load imbalances within any lane at any terminal
          • Equipment needs at any terminal in the lane
          • Driver needs at any terminal within the lane
          • Management of resources within the lane
    Simulation of trucking operations
  • 32.
    • Entities
      • Empty trailers at terminals
      • Loaded trailers:
          • Waiting to be grouped with other trailers
          • Waiting to be sent by relay, sleeper, or meet-and-turn mode
      • Transport Operators (sleepers, relay and meet-and-turn drivers)
      • Tractors
      • Trains at the railway station (if rail mode is activated)
    Simulation of trucking operations
  • 33.
    • Resources
        • Hostlers
        • Dispatchers
        • Fuelers
    • Activities / Processes that require special attention :
      • If only sleeper, relay and meet-turn operations are considered, the following activities are performed in a model:
          • Off load the loaded trailers after a trip at the dock
          • Load the empty trailers at the dock
          • Unhook trailers at a terminal
          • Prepare (hostler) equipment at a terminal : Get service from hostler to hook / unhook trailers with tractors / Get service at the fueling land or the inspection area
          • Drive the truck to the next location via sleeper mode sleeper / relay / meet-and-turn mode
    Simulation of trucking operations
  • 34.
      • If the rail mode needs to be modeled, the following activities are performed:
          • Movement of trailers to the rail-yard
          • Transportation of the trailers from the rail –yard to the terminal
          • At the destination terminal, split trailers at the rail-yard and dispatch to the terminal
    Simulation of trucking operations
  • 35.
      • Inputs Required for simulation
          • Trailer information
          • Trailer arrival process information
          • Scheduled arrival time distribution
          • Trailer information for each schedule : Lane destination, Load destination
          • Empty trailer availability information
          • Sleeper team arrival process at the origin terminals
          • Relay ( or meet and turn) driver arrival process at the original terminals
          • Tractor availability information
          • Other pertinent information related to any other dynamic process
          • Hostling times
          • A set of intermediate locations where sleeper (or relay) trucks stop for unhooking and or hooking or refueling
          • Fueling / Inspection times at a terminal
    Simulation of trucking operations
  • 36.
      • Fueling / Inspection times at a third party vendor location
      • Tractor service times at terminals
      • Current number of hostlers per shift at each of the terminals under consideration
      • Current number of sleeper, relay and meet-and-turn drivers
      • Standard driver roster:
          • Arrival times at the terminal
          • Number of drivers
          • Assigned destination
      • Extra driver roster
          • Number of drivers
      • Driver work rules and DOT regulations associated with sleepers, relay and meet-and-turn drivers
    Simulation of trucking operations
  • 37. Outputs from the simulation
      • Utilization of empty trailers at each terminal
      • Empty trailer build-up rate and its usage rate over a period of time
      • Utilization of drivers at each terminal over a period of time
      • Tractor utilization at each terminal and tractor buildup rate and usage rate at a terminal over a period of time
      • Number of trailers transported by sleeper teams, relay teams, or meet-and-turn drivers separately at all destination terminals for each day
      • Number of trucks on the road over a period of time
      • Number of trailers delayed due to unavailability of tractors at the terminals
      • Delay times for trailers at each terminal due to unavailability of tractors
      • Number of drivers delayed due to the unavailability of schedules at all terminals
      • Delay times for the drivers at each terminal due to unavailability of schedules
      • Number of tractors delayed due to the unavailability of trailers at each terminal
      • Delay times for tractors at each terminal due to unavailability of trailers
      • Hostler utilization
    Simulation of trucking operations
  • 38. Sample Simulation Outputs Simulation of trucking operations
  • 39. 3. Simulation of Truck Dock Operations
  • 40. Objective of Simulation
    • In case of truck dock operation simulations two fundamental objectives are set forth for the simulation study :
        • Studying the ways and means of increasing the throughput of a truck dock
        • Studying the impact of changes in a facility design before implementing it, to avoid making very costly errors
    • Generally following what-if scenarios are analyzed in this simulation:
        • To be able to show existing operations, trouble spots and changes in behavior of the existing truck dock as it undergoes changes in terms of new equipment, facility and operations
        • To study the impact of changes in processes and policies within each area of the truck dock
        • To change the distances traveled and capacity/size/number of forklifts and determine the impact on performance at the truck dock area
    Simulation of Truck Dock Operations
  • 41.
    • Entities and Resources
      • Yard – where trucks arrive and wait for an empty door
      • Doors
      • Transporters working at a dock such as forklifts and conveyors
      • Staging areas where the freight is temporarily stored prior to sorting and shipping
      • Sorting systems
    Simulation of Truck Dock Operations
  • 42. Processes
      • Determine door assignments to trucks (based on arrival behavior) at the unloading doors
          • Assign trucks to doors starting from left to right
          • Assign trucks based on origin or destination terminal to the pre-assigned doors
      • Determine door assignments to trucks (based on departure process) at the loading (outbound doors)
          • Employ a round- robin method of door assignment, if not waiting at the yard
          • Send trucks directly to next- available door, if not waiting at the yard
          • Send trucks to doors based on origin or destination terminal
          • Send trucks to a common waiting area and to next available door
      • Capture door arrival process
          • Enter the dock area for offloading
          • Consider truck / dock preparation time
          • Read the information pertaining to type of truck
          • Read the information pertaining to type of contents of the truck
    Simulation of Truck Dock Operations
  • 43.
      • Specify doors to forklifts
      • Assign, schedule and move and control forklifts for offloading trucks
      • Assign , schedule , move and control forklifts for loading trucks
      • Pickup and drop-off times for truck forklifts
      • Select a sortation conveyor
    Simulation of Truck Dock Operations
  • 44. Inputs Data for Truck-dock Simulation
    • Two types of data inputs are required. The first types involves freight types, door information, resources used and equipment specifications as follows:
        • Door information ( number of doors, door size ,door locations)
        • Freight types (containerized, bulk [sorted/unsorted], loose freight)
        • Resources (doors, forklifts, sorting conveyors)
        • Operators
        • Queue locations
        • Forklift specifications (number and types, length and width, loaded/unloaded speed, park locations, work assignment, turning rules, pickup and deposit rules)
        • Conveyor specifications (conveyor types, number of segments, input station characteristics, output station characteristics, segment speed, conveyor selection rules, freight movements)
    Simulation of Truck Dock Operations
  • 45.
    • Second type of input data involves rigorous data collection at the truck dock as follows:
        • Arrival process
        • Type of trucks based on freight carried
        • Frequency of truck arrivals
        • Truck contents (freight type and statistical distribution w/ parameters)
        • Truck hostling time distributions
        • Door preparation time before offloading
        • Door occupancy time by trucks after off-loading
        • Loading / Offloading times
        • Fork-lift pick up time by freight type
        • Fork-lift set down time by freight type at destination points
    Simulation of Truck Dock Operations
  • 46. Outputs from simulation
      • Measure the impact of eliminating certain truck types at inbound dock
      • Measure the Impact of additional doors
      • Measure the Impact of fork-lift assignment policies to doors
      • Determine optimum Number of doors required and forklift assignment policies
      • Time window to complete off-loading, staging and reloading all the trucks
      • Amount of work load expected at all areas that may receive freight during a time period
    Simulation of Truck Dock Operations
  • 47. Sample Outputs Simulation of Truck Dock Operations
  • 48. 4. Simulation of ramp operations in air cargo hubs Purpose of simulation model:
      • To develop a simulation model that has the ability to show ramp operations crew the problems, trouble spots, and changes in behavior of the existing ramp operations as the air-cargo hub undergoes changes
      • To study the impact of changes in operations and policies within each area of the ramp
      • To perform a comparative analysis, current versus new layout of aircraft parking, current versus new communication procedures, current new tug and dolly assignment rules and so on.
      • To study the impact of additional aircrafts and gates on the ramp and determine the number of K- loaders and tug and dollies
      • To study the impact of changing the number of dollies per tug and number of tugs per plane on the average time required to offload a plane. Study the impact of these operation parameters on the varying number of planes that arrive at the hub during a night
  • 49. Entities, Resources and Activities
      • Number of planes
      • Flight profile
      • Plane arrival time distributions
      • Total number of tugs
      • Number of tugs per plane
      • Number of dollies per tug
      • Number of K- loaders
    Simulation of ramp operations in air cargo hubs
  • 50. Inputs for simulation model
      • Number of gates
      • Ramp maps
      • Technical specifications of sort-line conveyors,tugs, dollies and forklifts
      • Plane types
      • Flight information
      • Tail sheet and arrival/ departure information
      • Number of container positions that each plane type can carry
      • Number of bellies
      • Number of containers each belly fills up by plane type
      • Number of dollies per tug
      • Team make-up for offloading and reloading container from/to a plane
      • Number of tugs/ dollies/ forklifts
      • Conveyor location and characteristics
      • Plane parking location rules
      • Runway behavior
    Simulation of ramp operations in air cargo hubs
  • 51. What – if Scenarios
      • Changes in number of tugs per plane
      • Changes in number of dollies hooked to each tug
      • Changes in total number of tugs used on the ramp
      • Changes in aircraft arrival process / departure process
      • Changes in number of K loaders
      • Changes in number of transfer forklifts
      • Changes in work rules
      • Impact of changes in the tug assignment to the aircraft
    Simulation of ramp operations in air cargo hubs
  • 52. Outputs for the simulation model
      • Total number of containers offloaded during an hour, total number of planes offloaded during an hour, average time to offload a plane, and completion time for offloading all the planes that arrived during night/ day
      • Offloading / Reloading times for 10 planes,20 planes, 30 planes and so on.
      • Determine number of gates for all arriving planes as created by the simulation model
      • Actual time at which the aircraft is fully offloaded or loaded
      • Offloading time for each aircraft that arrived during the night/day
    Simulation of ramp operations in air cargo hubs
  • 53. THANK YOU