2007 TRB Transportation Planning Applications Conference – Daytona Beach, Florida Pseudo Dynamic...
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Transcript of 2007 TRB Transportation Planning Applications Conference – Daytona Beach, Florida Pseudo Dynamic...
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Pseudo Dynamic Traffic Assignment
A Duration Based Static Assignment Process
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Planning Context: I-285 Strategic Implementation PlanARC RegionalTravel DemandModel24-Hour VolumesStatic Assignment Process13 County RegionSOV, HOV, Trucks and Transit
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Big Leap from Macro to MicroMicroscopicModelVISSIM24-Hour VolumesStatic Assignment Process13 County RegionSOV, HOV, Trucks and Transit15-Min. Volumes I-285 CorridorTraffic ControlITS StrategiesSOV, HOV and TrucksDynamic Traffic AssignmentARC RegionalTravel DemandModel1. Temporal distribution of traffic2. Better peak period paths
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Overall Modeling ProcessMicroscopicModelVISSIM24-Hour VolumesStatic Assignment Process13 County RegionSOV, HOV, Trucks and Transit15-Min. Volumes I-285 CorridorTraffic ControlITS StrategiesSOV, HOV and TrucksDynamic Traffic Assignment15-Min. Volumes 13 County RegionSOV, HOV and TrucksStatic Assignment ProcessARC RegionalTravel DemandModel1. Temporal distribution of traffic15-Min. Volumes 13 County RegionTraffic ControlITS StrategiesSOV, HOV and TrucksDynamic Traffic AssignmentMatrixVariegator2. Better peak period pathsMesoscopicModelDTA
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Planned Mesoscopic ApproachVISTANorthwestern UniversityOnly DTA program reported to be able to handle the problem size at the timeIssues encountered:Data assumptionsData preparationSoftware bugsMemory intensiveExcessive runtimesPlan B required
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Plan B Options ConsideredSuccessive Static AssignmentsWrite custom applications to track long tripsUse a different DTA packageCube Avenue, Dynameq, DynaSMART-P, etc.
Discovered an option in Citilabs software already in the assignment pathload function that enables volumes to be saved in travel time segments
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Pathload Option pathload path=TIME, vol[1]=mw[1], time=0-15, vol[10]=mw[1], time=15-30, vol[11]=mw[1], time=30-45, vol[12]=mw[1], time=45-60, vol[13]=mw[1], time=60-75, vol[14]=mw[1], time=75-99999
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Pseudo DTA Overview75 minute trip
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Pseudo DTA Preload Management
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Two-Zone Examples60-mile single-lane corridorAssume capacity of 2000 vphAssume free-flow speed of 60 mphLink sub-divided into 5-mile segments in order to see the progression of volume during the PDTA process
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Two-Zone ExamplesFree-Flow Traffic Conditions (1000 vph)
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Two-Zone ExamplesCongested Traffic Conditions (2000 vph)
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Two-Zone ExamplesOver-Saturated Traffic Conditions (3000 vph)
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I-285 Application
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Pseudo DTA - Validation
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Potential ApplicationsRefined time-of-day assignmentsEvacuation ModelingSpecial Events Arrival & DepartureLane Closures
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Questions / Comments