POLARIS Model

POLARIS Planning and Operations Language for Activity-based Regional Integrated Simulations Represents a “Transportation Language” for developing transportation simulation models Provided at high/low levels of abstraction, i.e. high-level transportation object model, operationalized by low-level programming and optimization concepts

Transportation Object Model (TOM) Transportation Simulation Framework (TSF) POLARIS Simulation Core Architecture (CORELIB) IPC Module Specific Model Implementation External Processes Execution Module

Transportation Object Model (TOM) TSF GetLandUse() GetActivityPattern() SimulateTrip() POLARIS Simulation Core Architecture (CORELIB) IPC Module ReadUrbanSim() Read/RunAmos() Read/RunMalta() SIMTRAVEL-P MALTA Execution Module { GetLandUse() While(World.IncrementTime() { GetActivityPattern() SimulateTrip() } UrbanSim AMOS

TRANSPORTATION OBJECT MODEL (TOM)

Transportation Object Model All objects in simulation are expressed as elements Elements have child elements, attributes and actions Events operate on attributes, child elements or parent element TOM abstracted from implementation level details World – Root Element – Child Elements: Spatial Elements Population Elements … – Attributes Time – Actions Access Element Increment Time …

Every “Thing" in a Transportation System Elements Actions Agents Proto- Agents Environment Parts of Elements Types of Elements Attributes Child Elements RequiredOptionalTentative Legend Travelers Signal Roadway Element

Parts of Elements Actions Associative Planning Types of Actions Processing Body Parts of Actions Informational Performing Pre- & Post- Conditions RequiredOptionalTentative Legend Take a Step Forward Choose a Route Talk to Someone Actions Linked Actions More To Be Determined

Membership Possession Types of Associative Actions Parts of Associative Actions Targeted Group RequiredOptionalTentative Legend Change Households Take Possession of a Car Join a Social Network Associative Actions More To Be Determined Types of Actions Associative

External Performance Internal Performance Types of Planning Actions Parts of Planning Actions Sequence of Actions RequiredOptionalTentative Legend Build a Signal Phase Sequence Choose a Destination Conceive a Road Closure Planning Actions More To Be Determined Types of Actions Planning

Agents Cognitive Reactive Environmental Types of Agents Attributes Parts of Agents Controlling Child Elements RequiredOptionalTentative Legend Travelers Intelligent Signal Systems Planning Groups Agents Types of Elements Actions - Planning - Information Plan

Transportation Object Model - Element Example Person – Child Elements: Money, Vehicle, Housing unit, etc. Anything else which can take action, have sub-elements, etc. – Attributes Age, Sex, Race, other person characteristics STANDARD ATTRIBUTES: – Current location, ID, Plan, etc. – Events (or Actions) Work, Sleep, etc. STANDARD EVENTS: – Move, Plan, Schedule, Take Inventory, Research, Observe, etc.

TRANSPORTATION SIMULATION FRAMEWORK (TSF)

Transportation Simulation Framework (TSF) Implement Standard / Element Specific Events or Actions When Element Calls Plan, TSF determines what this means and how to accomplish Defines the underlying Activity-Based Model, Route Selection and Microsimulation Architecture High level of abstraction from implementation details, for use by modelers. Implementation details found in POLARIS Architecture - CORELIB

Transportation Simulation Framework Example Examples: – Environment.Initialize – Environment.Locations.Add(1,1000) – Environment.Agents.Add(Person1) – Enviornment.Agents(P1).Move – Enviornment.Agents(P1).Plan(Act1) Framework defines model setup TSF has complete access to current agent and environment data – through CORELIB Must implement common ABM/Routing components: – Schedule, Plan, Route, in terms of Element.Actions CORELIB – defines all agent actions/interaction/calls to attributes, etc.

POLARIS Implementation Set up objects in TOM and simulation Framework in TSF For TIMESTEP t=0 to END – For Environment.Agent(0) to Environment.Agent.Size If (Agent.DoSomething) Then Agent.Action…. If (CallExternal) IPC.RunExternalProcess…. …

POLARIS-ADAPTS Example Required Events: – Planning Order Model, Conflict Resolution Model and, – Standard Events: Choose Destination, Choose Start Time, etc. New Plan order model requires modification to: – Standard event GenerateActivity – Standard element Activity GenerateActivity()

AMOS vs. ADAPTS example GenerateActivity() [in t] { Activity A A.setPlanTimeStart(t+0) A.setPlanTimeStart(t+1/t) A.setPlanTimeMode(t+1/t) A.SetPlanTimeWhoWith(t+2/t) } AMOS setup can use default generation of activities Uses small offset from current timestep to set processing order Activities planned as they are generated GenerateActivity() [in t] { Activity A A.setPlanTimeLocation(TSF.GetPlanTime(A,Loc)) A.setPlanTimeStart(TSF.GetPlanTime(A,Start)) A.setPlanTimeMode(TSF.GetPlanTime(A,Mode)) A.setPlanTimeWhoWith (TSF.GetPlanTime(A,Who)) } ADAPTS overrides default activity generator Set planning times in simulation future Using new GetPlanTime function written in TSF

ADAPTS Planner/Scheduler Handles at each timestep: – Generation – Planning – Scheduling Each step can occur at different times for same activity Core of the framework is the Attribute Plan Order Model At timestep t Generate new activity Update existing activity(s) Execute activity Attribute Planning Order model Planned Activity Schedule Time-of-Day t = Ttime Party t = Twith Mode Choice t = Tmod Destination choice t = Tloc Executed Schedule Resolve Conflicts Conflict Resolution Model Set Plan Flags: (Ttime,Tloc, etc.) Yes Decision Logical test Model Simulated events Yes No Yes No Activity Generation Activity Planning Activity Scheduling

How TSF uses TOM / CORELIB New function SetPlanTimes, example implementation in TSF TSF::SetPlanTimes(Activity A, type) { Agent P = Environment.Agents.CurrentAgent() If (P.IsEmployed && type=MODE) return Environment.Time Else return Environment.Time+2; } Interaction with Corelib – Return current agent – Evaluate Agent employment status – Evaluate environment time – Handles all memory access, translation of TOM, etc.

Interprocess Communicatons (IPC) Module Connect existing softaware to POLARIS framework Convert external software outputs into TOM elements/actions Called using external communication protocols in CoreLib Modeler must write conversion scripts to define the software input/output objects in TOM TOM Elements IPC Module (I/O Scripts) External Objects External Process POLARIS Model Communication Protocol Files Memory