1 UMR Lock 20 through 25 Simulation Model Inland Waterway Lock/Vessel Optimization Study Upper...
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1 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 Slide 2 2 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 Slide 3 3 The Bi-modal Distribution of Lockage Times at UMR Locks 20-25 for 2000-2003 Slide 4 4 The Distribution of the Wait For Lock Service at UMR Locks 20-25 for 2000-2003 Slide 5 5 The Seasonality Of System Use Total Lockages by Month at UMR Locks 20-25 for 2000-2003 Slide 6 6 Seasonality Of System Use (Continued) The Number of Tows Using the System Slide 7 7 Seasonality of the Wait For Lockage Time Distributions 2000-2003 Slide 8 8 Seasonality of Vessel Lockage Time Distributions 2000-2003 Slide 9 9 Seasonality of Non-Stop Pool Travel Time Distributions 2000-2003 Slide 10 10 Seasonality of Total Queue Sizes Locks 20 Through 25 2000-2003 Slide 11 11 Trend in Seasonality of Total Queue Sizes Locks 20 Through 25 2000-2003 Slide 12 12 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. Slide 13 13 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. Slide 14 14 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. Slide 15 15 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. Slide 16 16 Simulation Model Schematic Diagram Tow Traffic Slide 17 17 Simulation Model Schematic Diagram Recreation Vessel Traffic Slide 18 18 Simulation Model Detail Lockages 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). Slide 19 19 Simulation Model Detail Vessel 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) Slide 20 20 Comparison of 100 Runs of the Simulation Model with the 2000-2003 Omni Data Slide 21 21 Comparison of 100 Runs of the Simulation Model with the 2000-2003 Omni Data Slide 22 22 Comparison of 100 Runs of the Simulation Model with the 2000-2003 Omni Data Slide 23 23 Results of 100 Simulations with Existing Traffic Management N Minimum (hours) Maximum (hours) Mean (hours) Std. Deviation (hours) Wait Time - All Vessels All Locks 10031,143.4061,116.7440,702.855,307.23 Total Observable Tow Time 100169,512.60204,237.82181,323.966,190.18 Tow Time Large Tows 100108,497.10137,077.13118,881.225,317.35 Tow Time Small Tows 10057,684.9167,160.6962,442.741,674.04 Tow Wait Lock 201003,829.858,335.915,336.76784.76 Tow Wait Lock 211003,813.516,798.385,053.98615.79 Tow Wait Lock 221005,691.1317,226.158,711.921,773.16 Tow Wait Lock 241005,928.2819,839.579,720.142,185.98 Tow Wait Lock 251007,040.9618,466.779,992.271,791.80 Valid N (listwise)100 Slide 24 24 Results of 100 Simulations with an Example of a Locally Optimal Queue Re- sequencing Policy (Fastest First) N Minimum (hours) Maximum (hours) Mean (hours) Std. Deviation (hours) Wait Time - All Vessels All Locks 10029,259.4854,476.8737,212.134,385.33 Total Observable Tow Time 100168,436.65196,913.45177,727.755,109.69 Tow Time Large Tows 100112,430.95141,442.40122,072.555,167.35 Tow Time Small Tows 10052,090.2057,861.3255,655.201,066.37 Tow Wait Lock 201003,824.447,408.985,146.42653.88 Tow Wait Lock 211003,795.016,115.514,795.23488.64 Tow Wait Lock 221005,823.8612,302.298,068.921,297.46 Tow Wait Lock 241005,930.9418,577.349,184.831,966.61 Tow Wait Lock 251006,142.0212,082.588,135.891,164.66 Valid N (listwise)100 Slide 25 25 Changes Resulting from a Locally Optimal Queue Re-sequencing Policy (Fastest First) N Minimum (hours) Maximum (hours) Mean (hours) Std. Deviation (hours) Wait Time - All Vessels All Locks 100 -1,883.92-6,639.87-3,490.72-921.90 Total Observable Tow Time 100 -1,075.95-7,324.37-3,596.21-1,080.49 Tow Time Large Tows 100 3,933.854,365.273,191.33-150.00 Tow Time Small Tows 100 -5,594.71-9,299.37-6,787.54-607.67 Tow Wait Lock 20100 -5.41-926.93-190.34-130.88 Tow Wait Lock 21100 -18.50-682.87-258.75-127.15 Tow Wait Lock 22100 132.73-4,923.86-643.00-475.70 Tow Wait Lock 24100 2.66-1,262.23-535.31-219.37 Tow Wait Lock 25100 -898.94-6,384.19-1,856.38-627.14 Valid N (listwise)100 Slide 26 26 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.