Preempts Definition

Normal preempts are traditional preempts that are activated by a presence input or by a check-in/check-out input pair. Normal preempts have the typical track clearance, dwell, and exit states. All but the dwell state can be omitted.

There are 10 available preempts in the RBC. The signal groups and overlaps permitted in the dwell state will serve normally. Upon entering dwell, the controller will place calls to all dwell vehicle permit signal groups until one or more of these signal groups are timing.

Preempt Parameters (Preempt Parameters)
Track Clearances Parameters (Track Clearances Parameters)
Dwell parameter (Dwell Parameters)
Exit (Exit Parameters)
Preempt Inputs (Preempt Inputs)

Preempt Parameters

Preempt Number

Internal ID number per preempt

Enabled

Determines whether or not the Preempt is enabled to run:

No: Disables the preempt
Yes: Enables the preempt and allows the controller to respond to preempt calls.

Preempt Inputs

A Preempt is only activated by Inputs that are flagged in this parameter. A preempt input is active if either the preempt Presence input is active or the same preempt Check In/Check Out input has been checked-in.

Track Clearances Parameters

The duration of the track clearance states of Track Clearance 1 and Track Clearance 2. Any track clearance time that is zero will result in skipping that track clearance state.

Track Clearance 1	The time the Preempt will remain in the first track clearance state before advancing to the next preempt state. The track clearance timer will not begin until all signal groups and overlaps not permitted by the first track clearance state have been terminated. If this value it zero, then the first track clearance state will be skipped. Values permitted are zero to 255 seconds.
TC1 Veh SGs	Defines the signal groups that are permitted to time during Track Clearance 1. During the first track clearance state, these signal groups will be called and all other signal groups will be terminated and omitted after the preempt start green timing has been satisfied. The timer for this state will not begin until all Track Clearance 1 signal groups are green and when only signal groups flagged for this parameter are timing.
TC1 Ped SGs	Defines the pedestrian signal groups that are permitted to time during Track Clearance 1. Pedestrian signal groups not flagged for this parameter will be limited to preempt Start Walk and Start Ped Clr timing and will then be omitted during Track Clearance 1. The timer for this state will not begin until all non-Track Clearance 1 pedestrian signal groups have finished timing.
TC1 Ovl SGs	Defines the overlaps that are permitted to time during Track Clearance 1. During Track Clearance 1, overlaps not flagged for this parameter will be terminated and omitted after they have satisfied the preempt Start Green time. The timer for this state will not begin until all non-Track Clearance 1 overlaps have terminated.
Track Clearance 2	The time the Preempt will remain in Track Clearance 2 before advancing to the next preempt state. The track clearance timer will not begin until all signal groups and overlaps not permitted by Track Clearance 2 have been terminated. If this value it zero, then the Track Clearance 2 will be skipped. Values permitted are zero to 255 seconds.
TC2 Veh SGs	Defines the signal groups that are permitted to time during Track Clearance 2. During Track Clearance 2, these signal groups will be called and all other signal groups will be terminated and omitted after the preempt start green timing has been satisfied. The timer for this state will not begin until all Track Clearance 2 signal groups are green and when only signal groups flagged for this parameter are timing.
TC2 Ped SGs	Defines the pedestrian signal groups that are permitted to time Track Clearance 2. Pedestrian signal groups not flagged for this parameter will be limited to preempt Start Walk and Start Ped Clr timing and will then be omitted during Track Clearance 2. The timer for this state will not begin until all non-Track Clearance 2 pedestrian signal groups have finished timing.
TC2 Ovl SGs	Defines the overlaps that are permitted to time Track Clearance 2. During Track Clearance 2, overlaps not flagged for this parameter will be terminated and omitted after they have satisfied the preempt Start Green time. The timer for this state will not begin until all non-Track Clearance 2 overlaps have terminated.

Dwell Parameters

The dwell state defines the signal groups that are allowed to be served during the preemption state.

Dwell Veh SGs	Defines the signal groups that are permitted to time during the dwell state. At the start of the dwell state, these signal groups will be called and all other signal groups will be terminated and omitted after the preempt Start Green timing has been satisfied. The preempt will always enter the dwell state and remain there until all associated Preempt Inputs are inactive. It is possible to have the controller showing all red indications by not flagging any signal groups for this parameter.
Dwell Ped SGs	Defines the pedestrian signal groups that are permitted to time during the dwell state. Pedestrian signal groups not flagged for this parameter will be limited to preempt Start Green and Start Ped Clr timing and will then be omitted during the dwell state.
Dwell Ovl SGs	Defines the overlap signal groups that are permitted to time during the dwell state. During the dwell state, overlaps not flagged for this parameter will be terminated and omitted after they have satisfied the preempt Start Green time.

Exit Parameters

The Exit state defines the signal groups that will run immediately following the preemption, before the signal goes back to normal operation.

Exit Veh SGs	Before the preempt goes inactive, the controller will serve any vehicle signal groups flagged for this parameter. All other vehicle signal groups will be omitted until each of these signal groups is served at least once.
Exit Ped SGs	Before the preempt goes inactive, the controller will place a pedestrian call to any pedestrian signal groups flagged for this parameter. Also, any pedestrian signal groups that are already timing and flagged for this parameter will recycle their pedestrian signal group.

Preempt Inputs

Detector Type	This parameter determines which type of detector will be defined for the input in between Presence and Check In/Check Out.
Presence	Presence detector number to be used within Vissim for the corresponding Preempt input. Nnumbers hard coded as 401-410. Calls using this detector number will be lost when the vehicle leaves the detector.
Check In	Check-in detector number to be used within Vissim for the corresponding Preempt input, numbers hard coded as 411-420. Calls using this detector number will place a check in call with the Preempt. The call remains checked in until the corresponding Check Out detector gets a call. Value range [1 to 32767]
Check Out	Check-out detector number to be used within Vissim for the corresponding Preempt input, numbers hard coded as 421-430. Calls using this detector number will check out the Preempt.