HomeMy WebLinkAbout2012-06-20 PACKET 08.A.REQUEST OF CITY COUNCIL ACTION COUNCIL AGENDA
MEETING ITEM #
DATE 6/20/12
PREPARED BY Engineering Jennifer Levitt
ORIGINATING DEPARTMENT STAFF AUTHOR
COUNCIL ACTION REQUEST
Consider approving the recommended changes to signal operations at the following locations:
Jamaica and East Point Douglas Rd, East Point DouyIlas Rd and Cottage Grove Plaza, 80
Street and East Point Douglas Rd /Hardwood Ave, 80 h Street and Hinton Ave.
STAFF RECOMMENDATION
Approve the recommended changes to signal operations at the following locations: Jamaica
and East Point Douglas Rd, East Point Douglas Rd and Cottage Grove Plaza, 80 Street and
East Point Douglas Rd /Hardwood Ave, 80 Street and Hinton Ave.
BUDGET IMPLICATION $15,000.00 $15,000.00
BUDGETED AMOUNT ACTUAL AMOUNT
ADVISORY COMMISSION ACTION
DATE REVIEWED
APPROVED
DENIED
❑ PLANNING
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❑
❑
❑ PUBLIC SAFETY
❑
❑
❑
❑ PUBLIC WORKS
❑
❑
❑
❑ PARKS AND RECREATION
❑
❑
❑
❑ HUMAN SERVICES /RIGHTS
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❑
0 ECONOMIC DEV. AUTHORITY
0
0
SUPPORTING DOCUMENTS
® MEMO /LETTER: Jennifer Levitt, May 30, 2012
❑ RESOLUTION:
❑ ORDINANCE:
❑ ENGINEERING RECOMMENDATION:
❑ LEGAL RECOMMENDATION:
® OTHER: SEH, Cottage Grove Signal Operations,
Changes
and Recommendations
ADMINISTRATORS COMMENTS /! l
t
Ity Administrator Date
COUNCIL ACTION TAKEN: ❑ APPROVED ❑ DENIED ❑ OTHER
HACOUNCIL FORIAMCOUNCIL 20121Council 6- 20- 121Council Action Form Signal Timing.doc
From: Jennifer M. Levitt, P.E., City Engineer
Date: May 30, 2012
Re: Receive and Approve Recommended Traffic Signal Operations
Background
The City Council on February15, 2012 approved a traffic signal audit of the city's seven traffic
signals to ensure compliance with the latest regulations and ensure that operations at the
intersections are operating in an efficient and effective manner. As part of the report traffic
counts were done at each intersection and thorough site review of the operations was
conducted. Enclosed is a copy of the report that was completed for each intersection. The
consultant found many timing inconsistency with the city's traffic signals due to changes that
had occurred over the years on a case by case basis and some were needed to address
revisions that have occurred within the Minnesota Manual on Uniform Traffic Control Devices.
All of the signal timing recommendations were implemented following the submittal of the
report to staff.
Discussion
A summary of the recommendations by intersection are as follows:
Jamaica Avenue and East Point Douglas Road
Phase 1: 2012 Construction Season
• The left turns proposed to operate with protected - permissive with four - section
flashing yellow arrow.
• Cost of Phase 1: $8,000 This improvement is able to be funded through the
existing street light maintenance budget for 2012.
• Implementation will result in a reduction in delays, stops, fuel consumption
and pollutant emissions.
• Overall movements at the intersection will be served more quickly.
• Environmental benefits per year
• 7300 vehicle -hours of delay eliminated
• 200,000 stops eliminated
• 1700 gallons of fuel saved
• 500 pounds of pollutant emissions eliminated
Phase 2: Proposed with future road project
• Reconfigure center median at approach to intersection
• Reconfigure lane assignment at approach to intersection
■ Split phase operation on E. Point Douglas for additional fuel savings
o Provide intersection pavement tracking
Jamaica Avenue and 90 Street
Phase 1: 2012 Construction Season
• The left turns proposed to operate with protected - permissive with four - section
flashing yellow arrow.
• Cost of Phase 1: $9,000 This improvement is able to be funded through the
existing street light maintenance budget for 2012
• Implementation will result in reduction in delays, stops, fuel consumption
and pollutant emissions.
• Overall movements at the intersection will be served more quickly.
• Environmental benefits per year
• 2100 vehicle -hours of delay eliminated
• 110,000 stops eliminated
• 300 gallons of fuel saved
Phase 2: Budget for 2013
• Install master controller in the traffic signal cabinet will allow synchronizing of this
intersection with Jamaica & East Point Douglas, and East Point Douglas Cottage
Grove Plaza
• Cost = $20,000
East Point Douglas Road and Cottage Grove Plaza
Operation of the intersection could be improved with eliminating the use of left turn arrows on
one or more approaches during certain times of the day.
• There is no cost to this option, just programming changes
• The changing arrow scenario could cause driver confusion
Recommendation at this time is to monitor the intersection to see if timing changes improve
function of intersection, if not then the consultant's recommendation of eliminating the turning
arrow will be implemented. Additionally it is recommended to pursue installing tracking
markers across the intersection to improve lane recognition for motorists.
80 Street and East Point Douglas Road /Hardwood Avenue
Recommended changes involve changing the lane configuration of northbound Hardwood
Avenue, the anticipated traffic demands from growth did not materialize and the existing traffic
counts would indicate that the intersection would be better served with dedicated right turn
lane, instead of a through and right lane combination. The traffic counts warrant this change,
as predicted by previous Councilmember Grossklaus. This will improve traffic flow and reduce
stacking. Additional tracking markers are also recommended to improve lane recognition for
motorists.
2
80 Street and Hinton Avenue
Only recommended change would be to replace the time of school signs which indicate no
right turns in certain am or pm hours. This signing has become confusing and frustrating to
motorists, it is recommended to change the signs to no right turn when children are present. It
should be noted, during school hours a crossing guard is present.
80 Street and Hyde Avenue /Park High School
No recommended changes.
East Point Douglas Road and Grove Plaza
No recommended changes.
Recommendation
It is recommended the Council approve the recommended changes as outlined for each
intersection.
3
COTTAGE GROVE TRAFFIC SIGNAL OPERATIONS, CHANGES AND RECOMMENDATIONS
Signal Timing Changes — All Intersections
Basic traffic signal timing changes were made at all seven intersections. New timings at each
intersection are shown in Appendix A at the end of this document. Basic signal timing includes such
elements as the durations of walk and flashing don't walk intervals, minimum green times, yellow
change intervals, and red clearance intervals. These changes were made for a variety of reasons. In
several cases, the timings did not comply with new industry standards. For example, until the last few
years the duration of the flashing don't walk interval was calculated based on the pedestrian walking
speed of 4 feet per second. With the most recent version of the Minnesota Manual on Uniform Traffic
Control Devices (MMUTCD) that assumed walking speed has been reduced to 3.5 feet per second,
presumably to account for the aging population, requiring that flashing don't walk intervals increase at
virtually every intersection. The other primary reason timing changes were made was to provide
consistent timing through the system of traffic signals in Cottage Grove. Over the years, signal timing
parameters were implemented in many cases based on a "rule -of- thumb ". Although in many cases this
procedure provided a safe operation, there was a general lack of consistency from one intersection to
the next. Signal timings have now been changed to be consistent with guidelines in the MMUTCD and
recommendations by the Institute of Transportation Engineers (ITE) and the Minnesota Department of
Transportation (MnDOT).
Jamaica Avenue & East Point Douglas Road
The existing northbound (NB) and southbound (SB) left turn operation (from Jamaica Ave onto E Point
Douglas Rd) is currently protected -only, which means that left turns are permitted only during the green
left arrow interval or the yellow left arrow interval immediately following the green arrow. During these
intervals, oncoming through traffic on Jamaica Avenue has a red ball (circular red) indication. It is
recommended that this operation be changed to protected - permissive, which means that motorists are
permitted to turn left either during the green left arrow, during the following left arrow, or turning
through gaps in traffic during the interval when oncoming traffic has a green ball indication. It is further
recommended that the protected - permissive operation be accomplished through the installation of a
four - section flashing yellow arrow head, the top indication of which is a red left arrow, below which is a
yellow left arrow which remains steady on when activated. Below this arrow is another yellow left
arrow which flashes when activated. This yellow left arrow would flash when the oncoming traffic has a
green ball indication displayed. The bottom indication on the four - section head is a green arrow, which
is activated during the "protected" portion of the left turn sequence, i.e. when oncoming traffic has a
red ball indication. The four - section flashing yellow arrow head is recommended because it has become
the new standard in Minnesota for accomplishing protected - permissive operation, replacing the five -
section head consisting of a red ball, yellow ball, green ball, yellow left arrow, and green left arrow.
Research has shown that the flashing yellow arrow operation is more intuitive than its predecessor. In
addition, its installation allows for greater flexibility in left -turn operations. In addition to a protected -
permissive operation, the four - section head can be utilized for a protected -only operation, in which case
the flashing yellow arrow is not used, and for a permissive -only operation, in which case the green left
arrow is not used.
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Summary of Changes- 2012- 05- 02.docx SEH
The primary benefit of converting the NB and SB left turns at this location from protected -only
operation to protected - permissive operation is an overall reduction in delays, stops, fuel consumption,
and pollutant emissions encountered by motorists at the intersection. Because vehicles are permitted
to turn left if there are no oncoming through vehicles when the oncoming through movement has a
green light, those vehicles do not have to wait for the signal sequence to return to the green arrow
indication. In addition, because more left turn vehicles will be served during the permissive left turn
period, it is more likely that there will often not be vehicle waiting in the turn lane, which will allow the
green left arrow indication to be skipped and other movements to be served more quickly.
It is estimated that by changing the left turn operation at this intersection — making no other changes —
that annually in excess of 7300 vehicle -hours of delay, nearly 200,000 stops, over 1700 gallons of fuel
usage, and approximately 500 pounds of pollutant emissions could be eliminated.
Because of the difficulty motorists currently have in accessing the left -most westbound left turn lane,
often filling the turn bay and extending into the center lane, it is also recommended that the median
(circled in the aerial diagram) be modified to allow the left -most lane to extend to the previous
intersection. Tracking pavement markings, as shown in white and circled in Figure 3 could be employed
to encourage through traffic from the center lane of the previous intersection to enter the center lane at
this intersection, shifting to the left if so desired.
The consultant has also recommended that the existing split -phase signal operation on E Point Douglas
Rd at this intersection, which serves first one direction on E Point Douglas Rd and then the other, may
also result in savings in delay, stops, fuel usage, and pollutants. This change would require re-
configuring the lanes on East Point Douglas Dr approaching Jamaica Ave from the southeast, converting
the center lane from a left- through option lane to a through -only lane as shown by the red arrow in the
aerial photograph below. It is suggested that this potential improvement be re- visited after other
operational changes have been made.
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Summary of Changes- 2012- 05- 02.docx SEH
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Jamaica Avenue & 90 Street
Similar to the intersection at Jamaica Ave & E Point Douglas Rd, the intersection of Jamaica Ave & 90 St
could also benefit by converting the left turns from Jamaica Ave onto 90 St from protected -only
operation to protected - permissive. In addition, it is recommended that this conversion be accomplished
using the four - section flashing yellow arrow head for the previous intersection. While the benefits for
this intersection are less because of the significantly lower left turn volumes, it is estimated that annual
benefits would include a reduction in overall delay of over 2100 vehicle- hours, over 110,000 stops, and
300 gallons of fuel.
In addition, a master controller is installed in the traffic signal cabinet at this intersection. A master
controller can command multiple intersections to operate in a coordinated fashion by communicating
with the local controllers at those intersections. A key element in using the master controller is
communications to the intersections. It is recommended that sufficient cable be installed to connect
the three intersections in this area of the city to allow coordination. In the meantime, coordination of
the signals will be accomplished via time -based coordination, which involved keeping the clocks at all
three intersections synchronized.
!
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Summary of Changes- 2012- 05- 02.docx SEH 3
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East Point Douglas Road & Cottage Grove Plaza
Currently, three of the four directions at this intersection have left turn arrows, providing protected -
permissive control of left- turning traffic through the used of five - section heads (red ball, yellow ball,
green ball, yellow left arrow, and green right arrow). The consultant has suggested that the operation at
this intersection may be improved by eliminating the use of left turn arrows on one or more approaches
during certain times of day. This change could be accomplished without geometric or hardware
changes, simply through programming changes in the traffic signal controller —the device which changes
the traffic signal indications. However, to avoid motorist confusion by having left arrows displayed at
certain times of day and not at others, it has been decided to retain the existing operation (protected -
permissive operation at all times) at least temporarily, to determine if benefits attained through re-
timing of the signal systems are satisfactory at this point in time.
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Summary of Changes- 2012- 05- 02.docx SEH 4
Figure 2. Jamaica Avenue & 90 Street
Figure 3. East Point Douglas Road & Cottage Grove Plaza
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80 Street & East Point Douglas Road /Hardwood Avenue
The existing operation at this intersection controls eastbound (EB) and westbound (WB) 80 St left turns
using the protected - permissive strategy, and E Point Douglas Rd is controlled with split phasing,
primarily because of the high volume of NB left turning traffic during most periods of the day. Because
the high development- driven demand forecast for the southbound -to- eastbound left turn has not
materialized, it is recommended that the southbound lanes approaching the intersection from the north
be re- configured to include a right -turn lane, two through lanes, and a single left -turn lane. The red
arrow on the aerial diagram shows the change recommended. In conjunction with this change, it is
recommended that pavement markings tracking through the intersection in the southbound direction
be used to guide through traffic into the proper lanes on the south side. This tracking is shown in white
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Summary of Changes- 2012- 05- 02.docx SEH 5
circled on the aerial diagram below. This type of tracking is used to help guide vehicles through
intersections where lane lines do not line up across the intersection, for dual left turn lanes, and where
the approaches are slightly curved, as is the case here.
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80 St & Hinton Avenue, 80 St & Hyde Ave /Park High School, East Point Douglas Road & Grove Plaza
Shown in figures 5 through 7 are the three intersections where, aside from signal timing, no traffic signal
operational or geometric changes are recommended.
Figure 5 shows 80 Street and Hinton Ave, which contains an exclusive pedestrian across 80 Street,
which stops all vehicular traffic when pedestrians are crossing the east side of the intersection. This
provides a safe operation for students to cross, without causing significant vehicle delays or disruptions
in flow.
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Summary of Changes- 2012- 05- 02.docx SEH 6
Fig 5. 80 Street & Hinton Avenue
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Figure 6 shows the intersection of 80 Street and Hyde Avenue, with access on the north side of the
intersection to a parking lot at Park High School. No operational or geometric changes are
recommended here, as the protected - permissive left turn operation in the east /west direction and the
pedestrian crossings on the north and west sides serve the users well.
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Summary of Changes- 2012- 05- 02.docx SEH 7
Shown in Figure 7 is the intersection of East Point Douglas Road and Grove Plaza, which provided
protected - permissive left turn access from E Point Douglas Rd into the commercial areas on each side.
As for the signalized intersection just south of Jamaica Avenue, this intersection would likely have a
slightly more efficient operation during certain times of day using permissive -only left turns (i.e., not
activating the left turn arrows), but motorist confusion and the telephone calls generated probably do
not warrant a change from the existing 24- hour -a -day protected - permissive operation.
Summary of Changes- 2012- 05- 02.docx SEH
Figure 6. 80 Street & Hyde Avenue /Park High School
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Summary of Changes- 2012- 05- 02.docx SEH 9
Figure 7. East Point Douglas Road & Grove Plaza
Appendix A. Basic Traffic Signal Timing Changes
Move-
�nase ments
rain
Grn
Y!
PDW
Ext
R
ABAI
S/A
max
Init
TBR
fR
f.91n
Gap
Rcl
.a ^iaica Ave & E Pont Ooaglas Rd
SBLT
7
2.1
2
NB
18
2.1
4
1.S
30
5
NBLT
7
2.1
6
SB
14
2.1
4
i.5
30
7
EBLT ^ n
10
20
3.0
2.7
0
0.0
1 0
8
:'JBLTR
10
29
3.0
1 3.4
0
0.0
0
Jamaica Ave &90th St
_
1
SBLT
7
21
0
0
0.0
2
N8
7
17
2.1
4
1.5
30
0
0
0.0
3
E6
10
7
24
3.0
0
0.0
0
0
0
0.0
5
NBLT
7
2.1
0
0
0.0
6
$5
7
14
2.1
4
1.S
30
0
1 0
0.0
7
S
WB
10
7
24
3.0
0
0.0
0
0
0
0.0
E Poin Douglas Rd & Cott age Grove plaza
- _
1
WBL
3.5
2.2
2
E
13
3.5
2.2
3
NBL
5
3.5
3.0
S
3.5
3.0
none
EBL
5
3.5
2.2
6
VJB
16
3.5
2.2
7
S
NB
2S
3.5
3.0
80th St & E Point Douglas Rd /Hardrdood Ave
i
%'JBL
3.5
2.5
E
7
23
4.0
2.5
-
NB
7
25
3.5
3.0
S8
7
2S
3.S
3.0
5
ESL
3.5
2.5
6
%V5
1 7 1
23
1 4.0
1 2.5
7
7
25
3.5
3.0
SOth St & Hinton Ave S
1
E5
4.0
1.7
s
1 1.5
--
ruin
's
55
3.5
2.7
III -
EBL
3.5
1 1.7
6
l"JB
7
10
4.0
1.7
-
1.5
25
P:1in
7
SS-
7
21
3.5
2.7
8
80th St & Hyde Ave S
1
tNBL
3.5
1.S
2
EB
5
1.5
25
fain
3
4
56
10
3i
3.D
3.5
2.7
5
EBL
3.5
1.5
6
WB
7
5
1.5
2.5
Iviin
7
S
NB
10
3.0
3.5
2.7
E ,Point Douglas Rd & Grove Plaza
1
SSL
3.5
1.9
2
\' B
12
3.0
3.5
1.9
3
E
17
3.0
3.5
2.5
3.5
1.9
SS
I1
3. 0
3.5
1.9
r6 7 NBL
LNS
19
3.0
3.S
2.5
A
Summary of Changes- 2012- 05- 02.docx SEH 10
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