Urbanik, Tom

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Issues with Advance Train Preemption of Traffic Signals» >iTom Urbanik andRoelof Engelbrecht Texas Transportation Institute— wCopyright ©  2000 Texas Transportation Institute All rights reserved.Rail PreemptionDesign CaseQuestion•  Is this good enough to guarantee safe operations?Operations•  Variability impacts preemption operations•  Variability in traffic signal operations►Due to unknown controller state at preemption initiation►Affects right-of-way transfer time •  Variability in rail operations►Due to “train handling”►Affects warning timesCopyright ©  2000 Texas Transportation Institute All rights reserved.Data Collection•  Train monitoring opportunities at TTI ►Instrumented rail corridor in College Station, TX ►Good relationship with City of College Station•  Train data collection►Logged signal changes ►Logged preemptions ►Logged lights & gates ►Logged train arrivalsCopyright ©  2000 Texas Transportation Institute All rights reserved.30 35 40 45 50 55 60 65Preemption W arning Tim e (seconds)“Uncoupling” of EventsOperations (1)Preempt Lights Start Train ArrivesTo Controller To Flash At CrossingWarningTime ^ B H S il l l^ B W ^ M iB ^ iS S W H lii lS B  J.........  T  III! mill IN 11 i _Lights Lights FlashingGates delay h iu a M a a a iu iib i^ ^ ^ ^ iiB a ^ ^ u i^ ^ ^ *Signal ______________Maximum RWTT ^ ^ H Track_Gre0n | Yellow[  R ed / Dwell ^ ^ M_________________________  x  IQueueTime------ ►Copyright ©  2000 Texas Transportation Institute All rights reserved.Operations (2)Preempt To ControllerLights Start To FlashTrain Arrives At CrossingWarningTimeLightsGatesSignalQueuefixed .delayTrack Green YellowQueue Clearance TimeLights FlashingGates Descending Gates DownRed / DwellSeparation TimeTimeCopyright ©  2000 Texas Transportation Institute All rights reserved.Operations (3)“Preempt Trap”Track clearance green may end before warning lights start to flashVehicles have no indication of impending train arrival and may cross tracksBut the track clearance interval has already expired! mCopyright ©  2000 Texas Transportation Institute All rights reserved.SolutionsTreat the symptoms and / orTreat the causeTreat the SymptomsTreat the SymptomsPreempt To ControllerLights Start To FlashTrain Arrives At CrossingWarningl Advan TimeM (variaLightsGatesS ignal TnQueue Queue (|Gates Descending!fixeddelayTreat the Cause (one method)Treat the Cause (one method)ConclusionBe aware of the potential problems of advance preemptionTake the necessary steps to avoid (or at least minimize the probability of) the preempt trapConsider design and operationalscenariosCopyright ©  2000 Texas Transportation Institute All rights reserved.For More Informationhttp://transops.tamu.edu/content/gradecrossing.cfmMore extensive presentation Manual on good practice E-Mail: roelof@tamu.eduQuestions?

Issues with Advance Train Preemption of Traffic Signals

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Issues with Advance Train Preemption of Traffic Signals

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