Pseudo Dynamic Traffic Assignment

A Duration Based Static Assignment Process

Planning Context: I-285 Strategic Implementation PlanARC RegionalTravel DemandModel24-Hour VolumesStatic Assignment Process13 County RegionSOV, HOV, Trucks and Transit

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

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

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

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

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

Pseudo DTA Overview75 minute trip

Pseudo DTA Preload Management

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

Two-Zone ExamplesFree-Flow Traffic Conditions (1000 vph)

Two-Zone ExamplesCongested Traffic Conditions (2000 vph)

Two-Zone ExamplesOver-Saturated Traffic Conditions (3000 vph)

I-285 Application

Pseudo DTA - Validation

Potential ApplicationsRefined time-of-day assignmentsEvacuation ModelingSpecial Events Arrival & DepartureLane Closures

Questions / Comments