HomeMy WebLinkAboutRPT 6 SPECIAL SIGNING 03-07-88TO:
FROM:
SUBJECT:
'WILLIAM HUSTON, CITY MANAGER
PUBLIC WORKS DEPARTMENT/ENGINEERING DIVISION
REPORT ON REQUEST FOR SPECIAL SIGNING AT ALL SIGNALIZED
INTERSECTIONS WITHOUT PROTECTED LEFT-TURN PHASES
RECOMMENDATION'
Special si, gnal signs with the message "Left Turn Yield on Green Ball" should not be
installed at all signalized intersections within the City. The signs should be
installed only at intersections where a Permissive/Protected or a
Protected/Permissive type of signal phasing exists.
Since the City is phasing out its Permissive/Protective type of signals, the
special signs would be installed as an interim measure only at the locations where
protected left-turn phases are warranted. They would be removed after exclusive
left-turn arrows are installed.
aACKGROUND:
A request was made by City Council to the Engineering Department to review all
signalized intersections within the City without protected left-turn phases and
determine whether it would be appropriate to install s'pecial signs indicating "Left
Turn Yield on Green Ball".
DISCUSSION:
There are 21 signalized intersections within the City that have no exclusive
left-turn phasing. Hence, vehicles are permitted to make left turns through the
opposing traffic according to the availability of gaps (openings} in the traffic
'stream. The exceptions would be only if a sign is posted which prohibits such a
1 eft t urn movement.
It is standard traffic engineering practice not to post special signs informing
motorists to yield on the green ball signal indication. The majority of drivers
who have taken a drivers education class are instructed as to the driving rules of
the road and how to proceed through signalized intersections.
The special sign "Left 'Turn Yield on Green Ball" was developed for signalized
intersections that utilize a Permissive/Protected or a Protected/Permissive type of
signal phasing. The intent of the sign is to eliminate any possible confusion that
might develop when the protected left turn green arrow does not immediately light.
Typically, the left-turn arrow w. ill not light until four or more cars are in the
left-turn pocket, depending on whether the signal has leading or lagging left
turn phasing.
Presently, the City Traffic Engineer is completing his evaluation of the
Permissive/Protected signalized intersections within the City. Upon completion of
REPORT ON REQUEST FOR SPECIAL SIGNING
March 1, 1988
Page 2
the study, recomendations will be made to convert a number of the Permissive/
Protected signalized intersections to protected left-turn phasing. However, one of
his interim recommendations is to install the special sign "Left Turn Yield on
Green Ball" at locations where the Permissive/Protected type of operation is going
to be converted to protected left-turn phasing. After installation of the
protected green arrows, the signs would be removed. The cost for each of these
special signs is $40.
Therefore, it is Staff's recommendation that the special sign "Left Turn Yield on
Green Ball" only be installed at locations where a Permissive/Protected or a
Protected/Permissive type of signal phasing exists.
Bob Ledendecker
Director of Public Works/City Engineer
Dennis D. Barnes
City Traffic Engineer
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