Specifications

7-20
Note: The following ON, GRN and OFF status values
represent points in the active cycle. They are
meaningful only when the unit is in coordinated
operation.
ON: The point in the active cycle that the TP input
becomes active
GRN: The point in the active cycle that the TP phase
green becomes active. If there is more than one
TP phase (dual ring) it is the first point when both
are green.
OFF: The point in the active cycle that the TP input
goes away, clears, or is inhibited due to max wait
time out, max extend time out, and/or fail.
RAW TRANSIT PRIORITY INPUTS STATUS SCREEN
Transit priority inputs can also be viewed from the raw
inputs screens. To get to these, hit;
Main Menu-1-1-6-8-Page Down 23 times.... .
“X’s” indicate which input is active. These are the
Transit priority call inputs 1-6 and the Transit priority
inhibit. See page 2 for input definitions.
Tip: Because of the numerous paging down necessary
to get to this screen, it is a good choice for the
LMD9200 “Hot Key” function. To use it, simply select the
screen using menus and paging down as above. After
the screen is obtained, hit the decimal key then any digit
0-9. From that point on, the same screen can be
selected from any other run screen by pressing that one
key 0-9 (do not hit decimal again, that is only for
assigning the key the first time).
PG dwn etc. for Transit Priority Call Clear inputs 1-6
and Phase 1-8 conditional transit priority shorten
INHIBIT inputs.
USE OF TRANSIT PRIORITY FOR QUEUE (BACK-
UP) ALLEVIATION
GENERAL
Transit Priority operation was developed to provide
more efficient operation for Transit vehicles. During the
development process, however, it became apparent that
this feature may have other uses as well. Most notably
of these is to alleviate queues and temporary back ups
at coordinated intersections.
Example
Say that for the coordinated intersection below the
Southbound phase 2 approach occasionally overloads
and backs-up. Say that when this occurs phase 1
remains fairly normal. Assume that the back-ups are
occasional and not continuous. If the back-ups were
continuous, the situation would need to be addressed by
invoking a longer cycle and/or split with more phase 2
green time for the period.
To address this occasional situation, set-back loops are
placed and wired into TP inputs. The TP inputs are set-
up with delays and will call phase 2 if the delay timer
times out. An appropriate TP extend time is provided.
In some cases such as this, pre-emption may have
been used to exhaust the backed-up queue. The TP
feature may provide some advantages because, unlike
pre-emption, other phases are not as abruptly
terminated or skipped and the cycle timing is largely
preserved.
Set-back loops
connected to TP
inputs. TP input set
up with delay (me-
mory off) to call
phase 2 if the delay
timer times out.
TPr1X TPr2 TPr3 TPr4 TPr5 TPr6 TPrI
152X 233 0 0 0 0 0
OR OR OR OR OR OR OR
0 0 0 0 0 0 0
φ1
φ2
φ2
φ1