Specifications

7-16
TRANSIT PRIORITY COORD OPTIONS
This menu provides optional programming related to
coordinated operation
Selection 4....
CYCLE & SPLIT TO MAX/WLK GP 1-3 Selection 1....
The example screen shows group 1 assigned to all
cycle 1 splits, group 2 to all cycle 2 splits and group 3 to
all cycle 3 splits.
For each cycle and split, assign the desired TP group 1-
3 to be used when that cycle/split is in effect. The
assignment pertains to both max and walk groups (e.g.
group 1 = select both group 1 max’s and group 1 walks
when that cycle/split is in effect).
PRE TP CYCLE LEADING LIMITS.....Selection 2.....
LIMIT: 0 = Not used, no limit
1-255 = Maximum number of seconds ahead of
force off phase is allowed to terminate
under TP control
Used for coordinated operation, these values limit the
amount that any individual phase can be shortened
relative to its force off point within the cycle timer. The
TP group max times also affect phase timing in con-
junction with these values--see the discussions on TP
max and walk value computations during coordinated
operation.
The cycle leading limits have the following effects :
-For any CNA coord phase it prevents hold from being
released too early and thus causing a short timed phase
(usually the major street). Note: The user must
program CNA coord phases to force off at the yield
point (end of walk) for this to work properly--not the end
of green.
In two phase operation the limit values may used to
protect against cases in which phases are somehow
allowed to start very early and it is not desired to have
them terminate correspondingly early. For two phase
operation, however, the TP group Max timings alone will
generally determine how far ahead of the cycle the
phase can get since the unit can only be in one other
phase besides the TP phase. There is no theoretical
accumulation of earliness. It is still not a bad idea to use
leading limits in this case.
-In multi-phase operation (3 or more phases) the limit
values do prevent the accumulation of individually
shortened times to get to such a magnitude that latter
phases get too far ahead of the cycle.
Note that the limit values only restrict the ability of the
Transit Priority process to cause a phase to terminate
too early. Actuated phases can always gap-out.
POST TP MAX EXT’S UNTIL 1ST FO
This option adds a value called the POST TP MAX EXT
time to the normal max time of all non-CNA phases
once the TP phase has been achieved. This process
occurs only at the beginning of each phase when the
max timer is initialized (no dynamic adjustment). Once
started, it will continue to do so until some (any) force off
occurs.
Selection 3.....
The feature can be used to protect against early phase
max-outs following transit priority service. This may
be required when phases, including and especially the
TP phases themselves, are served significantly early
due to the TP process. This is likely to occur when a
queued TP vehicle calls for service, compels other
phases to leave early, and then gets right through when
the green comes. Under such circumstances without
this option; since the phase would start early, it may
max out early as well (relative to its force off). This could
be detrimental to progressions in coordinated operation,
especially for grid systems where side phases are also
--TRANSIT PRIORITY COORD OPTIONS--
1. CYC & SPLIT TO TP MAX/WLK GPS 1-3
2. PRE TP CYCLE LEADING LIMITS
3. POST TP MAX EXT’S UNTIL FIRST FO
--CYCLE AND SPLT TO TP MAX/WLK GP 1-3
CYC 1 2 3 4 5 6 7 8
SPLT 1/2 1/1 2/2 3/3 0/0 0/0 0/0 0/0 0/0
SPLT 3/4 1/1 2/2 3/3 0/0 0/0 0/0 0/0 0/0
- LIMIT PH’S CAN GET AHEAD OF CYCLE -
PHASE 1 2 3 4 5 6 7 8
LIMIT 12 15 0 0 0 0 0 0
(0 = NO LIMIT, 1-255 LIMIT IN SECS)
POST TP PH MAX EXT’S UNTIL 1ST F.O.-
PHASE 1 2 3 4 5 6 7 8
MAX EXT 10 10 0 0 0 0 0 0
AUT EXT OFF ON OFF OFF OFF OFF OFF OFF