UMR Lock 20 through 25 Simulation Model

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UMR Lock 20 through 25 Simulation Model

• Inland Waterway Lock/Vessel Optimization Study
• Upper Mississippi River Locks 20-25
• Center For Transportation Studies
• University Of Missouri, St. Louis
• 15 June 2005

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The Need for a Simulation Model

• Why is a simulation model needed to evaluate
  alternative traffic management policies on the
  UMR?
• The seasonality of traffic demands, vessel
  operations, and lock operations
• The interdependence of individual vessel lockage
  times
• The scope of the management measures under
  evaluation and their systemic impacts

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The Bi-modal Distribution of Lockage Times at UMR
Locks 20-25 for 2000-2003
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The Distribution of the Wait For Lock Service at
UMR Locks 20-25 for2000-2003
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The Seasonality Of System UseTotal Lockages by
Month atUMR Locks 20-25 for 2000-2003
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Seasonality Of System Use (Continued)The Number
of Tows Using the System
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Seasonality of the Wait For Lockage Time
Distributions2000-2003
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Seasonality of Vessel Lockage Time Distributions
2000-2003
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Seasonality of Non-Stop Pool Travel Time
Distributions 2000-2003
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Seasonality of Total Queue Sizes Locks 20 Through
25 2000-2003
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Trend in Seasonality of Total Queue Sizes Locks
20 Through 25 2000-2003
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The Simulation Model

• A discrete event simulation model of the segment
  of the UMR composed on Locks 20 through 25 and
  connecting pools is constructed using Micro
  Analysis and Designs Micro Saint Sharp.
• Micro Saint Sharp is a widely used, commercially
  available software package designed to build
  discrete event simulation models that facilitates
  model building and animation.
• Any user with a Micro Saint Sharp license may use
  and alter the simulation model.
• Simulation results may be analyzed in Micro
  Saint, any statistical package, and most
  spreadsheet applications.

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The Simulation Model

• Vessels (large tows, small tows, and recreation
  craft) enter the system at one of ten entry
  points following seasonally estimated,
  independent inter-arrival time distributions.
• Vessels complete a lockage after system entry and
  then make a seasonally adjusted decision to (1)
  continue to the next sequential lock in their
  direction of travel (2) stop or (3)
  re-configure their flotilla. If vessels stop or
  re-configure their flotilla, they are terminated
  in the appropriate pool after completing their
  lockage and then later regenerated in the pool in
  which they terminated.
• All recreation craft are terminated after a
  single lockage.

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The Simulation Model

• Vessel lockage times depend on the vessel
  configuration, the direction of travel, the month
  of occurrence, and the state of the lock when the
  lockage occurs.
• Pool transit times depend on the vessel
  configuration, the direction of travel, and the
  month of occurrence.
• Periods of lock closure are modeled as
  independent occurrences with independent
  durations.

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The Simulation Model

• Monthly and annual measures of system output and
  performance such as the categorized tow-miles
  produced, categorized utilized tow hours,
  categorized lockage times and utilizations,
  categorized lock delay times, and categorized
  pool transit times are recorded.
• The performance measures are analyzed using both
  Micro Saints built in analytical tools and SPSS.

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Simulation Model Schematic DiagramTow Traffic
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Simulation Model Schematic DiagramRecreation
Vessel Traffic
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Simulation Model DetailLockages

• There are 360 classes of lockages (lognormal
  distributions) at each lock characterized by
• Direction of vessel travel (upbound, downbound)
• Class of vessel (multi-cut tow, single cut tow,
  jackknife, knockouts, and recreation traffic)
• Lockage type (fly, turnback, exchange) and
• Month of occurrence.
• Locks are periodically made not available to
  service vessels (exponential distributions).

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Simulation Model DetailVessel Traffic

• Seasonally adjusted independent entrances of four
  different types of tows at ten separate system
  locations (exponential distributions)
• Seasonally adjusted transition probabilities for
  directing each class of tow movement through the
  system
• Seasonally adjusted independent lock-specific
  recreation vessel arrivals (exponential
  distributions)
• Seasonally adjusted and directionally specific
  travel times for four separate tow classes
  through the lock pools (lognormal distributions)

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Comparison of 100 Runs of the Simulation Model
with the 2000-2003 Omni Data
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Comparison of 100 Runs of the Simulation Model
with the 2000-2003 Omni Data
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Comparison of 100 Runs of the Simulation Model
with the 2000-2003 Omni Data
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Results of 100 Simulations with Existing Traffic
Management
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Results of 100 Simulations with an Example of a
Locally Optimal Queue Re-sequencing Policy
(Fastest First)
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Changes Resulting from a Locally Optimal Queue
Re-sequencing Policy (Fastest First)
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Vessel Re-sequencing Discussion

• Mean annual reduction of approximately 3,600
  total tow hours required to complete the same set
  of vessel itineraries.
• This reduction represents approximately a 2
  decrease in equipment time needed to complete the
  same set of movements through these five locks.
• Some vessels win and other vessels lose.
• System performance variability is also reduced.