TC - Agenda - 11-01-05AGENDA
ROSEMEAD TRAFFIC COMMISSION
8838 East Valley Boulevard
Rosemead, California 91770
Regular Meeting
SEPTEMBER 1, 2005
Call to Order: 7:00 p.m.
Roll Call: Chairman Quintanilla, Vice - Chairperson Matsdorf,
and Commissioner Knapp
Pledge of Allegiance: Commissioner Matsdorf
Invocation: Commissioner Knapp
I. APPROVAL OF MINUTES - Deferred until October 6, 2005
II. ORAL COMMUNICATIONS FROM THE AUDIENCE - This is the time
reserved for members of the audience to address the Commission on items not
listed on the agenda. (Maximum time per speaker is three (3) minutes; total time
allocated is fifteen (15) minutes).
III. OLD BUSINESS - NONE
IV. NEW BUSINESS
A. REQUEST FOR LEFT TURN SIGNAL PHASING ON DEL MAR
AVENUE AT GRAVES AVENUE
V. STAFF REPORTS
VI. COMMISSIONER REPORTS
VII. ADJOURNMENT - To the next regular meeting of the Traffic Commission on
Thursday, October 6, 2005, at 7:00 p.m., Rosemead City Council Chambers, 8838
East Valley Boulevard, Rosemead, California 91770.
Posted 72 hours in advance of the meeting at: Rosemead City Hall, 8838 East Valley
Boulevard, Rosemead; the L.A. County Library, Rosemead Branch, 8800 E. Valley
Boulevard; and at other locations pursuant to RMC Section 1.08.
Staff Report
Rosemead Traffic Commission
TO: HONORABLE CHAIRMAN
AND MEMBERS
ROSEMEAD TRAFFIC COMMISSSION
FROM: JOANNE ITAGAKI, TRAFFIC ENGINEERING DEPUTY
DATE: August 23, 2005
RE: Request for Left Turn Signal Phasing on Del Mar Avenue at
Graves Avenue
REQUEST
Councilmember Nunez has requested staff analyze the intersection of Del Mar
Avenue and Graves Avenue for the installation of left turn signal phasing on Del
Mar Avenue. Councilmember Nunez is concerned that vehicles, especially
southbound, have difficulty turning left due to the speed of traffic and the vertical
curve north of Graves Avenue.
CONDITIONS
Del Mar Avenue is a 64 -foot wide north -south roadway with two lanes of traffic in
each direction. A double yellow centerline separates opposing lanes of traffic.
There are dedicated left turn lanes in both the northbound and southbound
directions of Del Mar Avenue at Graves Avenue. The posted speed limit on Del
Mar Avenue is 35 mph.
Graves Avenue is a 54 -foot wide east -west roadway with one lane of traffic in
each direction. In the vicinity of Del Mar Avenue, the opposing lanes of traffic are
separated by a double yellow centerline. There are dedicated left turn lanes in
both the eastbound and westbound directions of Graves Avenue at Del Mar
Avenue. The posted speed limit on Graves Avenue is 35 mph.
DATA
The reported collision history at the intersection of Del Mar Avenue and Graves
Avenue was reviewed for the period from January 1, 2000 to May 2005. These
collisions will be summarized in Exhibit A, available at the Traffic Commission
meeting. There were 8 collisions reported during this period within 250 feet of
the intersection. Four of these collisions occurred in 2000. Two collisions
occurred in 2002 and two occurred in 2003. There were no reported collisions in
2004 or 2005.
City staff is in the process of requesting any additional reported collisions at the
subject intersection with the California Highway Patrol (CHIP). This request is
September 1, 2005 Traffic Commission Meeting
Request for Left Turn Signal Phasing on
Del Mar Avenue at Graves Avenue
Page 2 of 4
being made because Del Mar Avenue and Graves Avenue is on the City .
boundary with parts of the intersection in the County. It is possible that reported
collisions might not be in the City's database. Staff will update the reported
collision history at the Traffic Commission meeting.
Turning movement counts were taken at the intersection in July. These counts
revealed the following:
DISCUSSION
Field observations of the intersection of Del Mar Avenue and Graves Avenue
were made at several different times of the day. Overall, the traffic volumes and
traffic flow at the intersection are very light with minimal delay and congestion
experienced. In reviewing the left turn movements on Del Mar Avenue, the
southbound left turn direction was found to have some visibility constraints during
certain times of the day.
Like the installation of a traffic signal, the Manual of Uniform Traffic Control
Devices (MUTCD) provides guidelines for the installation of left turn phasing.
These guidelines are as follows:
1. Accidents — Five or more left turn accidents for a particular left turn movement
during a recent 12 -month period.
AM Peak 7:45 -8:45
PM Peak 5:00 -6:00
Northbound
Left Turn
167
223
Straight
388
557
Right Turn
34
36
Southbound
Left Turn
46
75
Straight
496
454
Right Turn
46
53
Eastbound
Left Turn
61
59
Straight
136
184
Right Turn
233
216
Westbound
Left Turn
34
24
Straight
173
154
Right Turn
61
69
DISCUSSION
Field observations of the intersection of Del Mar Avenue and Graves Avenue
were made at several different times of the day. Overall, the traffic volumes and
traffic flow at the intersection are very light with minimal delay and congestion
experienced. In reviewing the left turn movements on Del Mar Avenue, the
southbound left turn direction was found to have some visibility constraints during
certain times of the day.
Like the installation of a traffic signal, the Manual of Uniform Traffic Control
Devices (MUTCD) provides guidelines for the installation of left turn phasing.
These guidelines are as follows:
1. Accidents — Five or more left turn accidents for a particular left turn movement
during a recent 12 -month period.
September 1, 2005 Traffic Commission Meeting
Request for Left Turn Signal Phasing on
Del Mar Avenue at Graves Avenue
Page 3 of 4
2. Delay — Left -turn delay of one or more vehicles, which were waiting at the
beginning of the green interval and are still remaining in the left turn lane after
at least 80% of the total number of cycles for one hour.
3. Volume — At new intersections where only estimated volumes are available,
the following criteria may be used. For pre -timed signal or a background -
cycle- controlled actuated signal, a left turn volume of more than two vehicles
per approach per cycle for a peak hour; or for a traffic- actuated signal, 50 or
more left turning vehicles per hour in one direction with the product of the
turning and conflicting through traffic during the peak hour of 100,000 or
more.
4. Miscellaneous. Other factors that might be considered include but are not
limited to: impaired sight distance due to horizontal or vertical curvature, or
where there are a large percentage of buses and trucks.
For. the intersection of Del Mar Avenue and Graves Avenue, the guidelines are
compared as follows:
1. Accidents — The highest number of reported accidents occurred in 2000 with
4 reported collisions. Three of these collisions would be considered left turn
accidents. However, the year 2000 would not be considered a 'recent 12-
month period'. The most recent reported accident occurred in 2003.
Therefore, this guideline is not satisfied.
2. _Delay — Based on the field observations of the intersection, it is estimated that
less than 80% of the signal cycles experience some delay to the left turning
vehicles. Therefore, this guideline is not satisfied.
3.' Volume — This intersection is not a new intersection but the relationship to the
product can be made as a comparison. The northbound left turn volume
product in the AM is 82,832 and in the PM is 101,242. For the southbound
left turn volume produce, the AM is 17,848 and in the PM is, 41,775.
Therefore, the volume product is satisfied in the northbound direction during
the PM peak hour.
4. Miscellaneous. The visibility of northbound traffic while in the southbound left
turn lane is usually clear with the horizontal and vertical curves on Del Mar
Avenue south of Graves Avenue. On average, a southbound left turning
vehicle can first see a northbound vehicle approximately 12 seconds before
that vehicle reaches the intersection. This is an adequate amount of time for
motorists to determine when an adequate gap in traffic occurs. However,
when there is a long line of northbound left turning vehicles in the left turn
lane, the vehicles' block the visibility of northbound through traffic for
southbound left turn lanes. The 12 second time visibility time is reduced
significantly to less than 5 seconds.
RECOMMENDATION
September 1, 2005 Traffic Commission Meeting
Request for Left Turn Signal Phasing on
Del Mar Avenue at Graves Avenue
Page 4 of 4
Based on the reduced visibility discussed above, it is recommended that left turn
phasing be installed in the northbound and southbound directions of Del Mar
Avenue at Graves Avenue.
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