Facility Planning with Simulation A Case Study

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Facility Planning with SimulationA Case Study

• Kutlu Rahmi Evlioglu
• Booz Allen Hamilton Inc.
• Session 6 Infrastructure Planning with Modeling
  and Simulation

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Agenda

• Problem Statement
• Software Selection
• Simulation Model
• Base Case Results
• Sensitivity Analysis
• Expected Next Steps

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Problem Statement

• Develop a micro computer simulation model of bus
  operations in a three level facility. The model
  will be used to evaluate
• Current operational efficiency of the facility
• Analyze future scenarios under increased demand
• Assess the impact of proposed physical changes to
  the terminals infrastructure, if ever there is a
  need

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Problem Statement - Continued

• The simulation model will be packaged with a
  customized user interface as a tool for the
  client so that
• Limited sensitivity runs can be conducted through
  the user interface
• Changes to model can be performed by the client
  with training

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Software Selection

• Software selection based on 26 criteria
• 8 from statement of work (e.g. flexibility, data
  import/export, visualization)
• 9 as Booz Allen criteria (e.g. familiarity with
  the tool, ease of use)
• 9 as modeling challenges specific to the task
  (e.g. entity tracking, dynamic path changes)
• Out of initial group of 18 software packages,
  selected 4 for in-depth analysis
• Extend (multi-purpose)
• Arena (multi-purpose)
• VISSIM (vehicular traffic)
• Java (custom modeling)

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Software Selection - Continued

• Comparison of strengths (samples) specific to the
  task

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Software Selection - Continued

• Comparison of weaknesses (samples) specific to
  the task

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Software Selection - Continued

• Software selection approach based on best
  practices derived from
• MAUA (Multi Attribute Utility Analysis)
• AHP (Analytic Hierarchy Process)
• Simple grading scale, not weighted, constant and
  exponential weight assignments

VISSIM

• Arena was chosen to be the simulation software
  for this particular modeling effort

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Simulation Model

• Arena simulation model of the facility was
  developed by using transporters and networks. All
  transporter movements in the model follow these
  shortest-distance paths defined by the system
  map, automatically generated in Arena.

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Simulation Model - Continued
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Simulation Model - Continued

• User interface

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Base Case Results

• For comparison, accumulation levels from the
  model and on-site observations are shown on the
  same chart
• The base case data should not necessarily match
  the on-site observations, as they occurred on
  different days, with different schedules

Only morning and afternoon peaks are shown.
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Base Case Results - Continued

• Gate Utilization Percentage of time gate is
  occupied during the peak periods.

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Base Case Results - Continued

• Time in Terminal The difference from the time
  the buses are at the level entry until they exit
  the level, including the dwell time at their
  gates

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Base Case Results - Continued

• Stopped Delays Buses accumulate stopped delays
  when they are unable to advance to their
  destinations due to congestion, when other buses
  have right of way, etc.

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Sensitivity Analysis

• Utilization of a bus storage facility with
  immediate access from the bus terminal is
  studied.
• The purpose of the facility is to provide
  temporary storage for buses when they arrive at
  the terminal significantly earlier than the
  scheduled departure time.
• The buses are directed to the storage facility
  based on a pre-determined cut-off time, the
  difference between the time the bus is at the
  beginning of the entry ramp and its scheduled
  departure time.

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Sensitivity Analysis - Continued

• When a storage facility is utilized, the average
  time buses spend on the busiest level goes down
  as much as 36 percent.

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Expected Next Steps

• Explore operational improvements by
• Changing gate assignments
• Moving operations between levels
• Expanding operations by adding gates when
  feasible
• Expand the boundaries of the model to include a
  storage facility based on feasibility and use the
  model to
• Determine short-term and long-term storage
  requirements
• Study various layouts

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Questions