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DATE 12 2-06
COUNCIL ACTION FORM
SUBJECT: SPEED LIMIT ON STANGE ROAD
BACKGROUND:
On October 24, 2006, the Mayor and City Manager received a correspondence
regarding the posted speed limit on the portion of Stange Road within the Somerset
Subdivision. The individual cited a safety concern relating to vehicles traveling on the
section of Stange Road between Aspen Road and Northridge Parkway, specifically the
curved sections of roadway around the Stange Crescent Park. The request was for City
staff to review the feasibility of reducing the speed limit on Stange Road from 24th
Street, north, to Aspen Road from 30 miles per hour to 25 miles per hour.
On November 9, 2006, a letter to the Mayor and City Council was received from Jerry
Pierce regarding a potential sight blockage caused by landscaping located at the
southern end of Stange Crescent Park. Mr. Pierce stated in his letter that the existing
wooden sign and surrounding shrubs block visual contact with southbound vehicles on
Stange Road for motorists stopped at the westbound approach of the Stange Road and
Northridge Parkway intersection, thereby creating a safety concern.
Speed Limits on Stange Road
Currently, the speed limits on Stange Road are designated as thirty (30) miles per hour
between 24th Street and Kingston Drive, and thirty-five (35) miles per hour between
Kingston Drive and Bloomington Road (see Attachment C for diagram).
In response to the safety concern, traffic engineering staff conducted a speed study for
northbound and southbound traffic traveling contiguous to Stange Crescent Park. Data
was collected from Tuesday, October 31, 2006, starting at 11:00 a.m. and ran until 2:00
p.m. on Thursday, November 2, 2006. In doing so, staff was able to collect a full 48
hours of vehicle data representative for a typical workday. This data will be the basis for
the first part of this report.
Four main types of data were used to evaluate traffic traveling on Stange Road: 85th
Percentile Speed', Pace 2, ADT3, and Estimated Delay for Peak Hour AM/PM4 (LOS)
(see Attachment B for definitions). A summary for this study has been provided in Table
1 (see Attachment A, Figures 1-4, for respective time-of-day analysis).
Table 1
StangeRoad •
ark
1 1 . to 1 .
5 z r r3'A "i5
85th Percentile Speed (30 mph limit) 29 30 mph
Pace (% of Population) 21 - 30 (74.92%) 23 - 32 (81.13%) mph
Average Daily Traffic 2500 2300 veh.
Est. Peak Hour Delay AM,PM (LOS) 1.8(A) , 8.2(A) 5.6(A) , 3.1(A) sec.
Staff also conducted an analysis of the available departure sight distances at the
intersections of Northridge Parkway and Aspen Road. This analysis followed
engineering standards as specified in Chapter 9 of AASHTO's "Green Book", which is
the national standard for geometric highway design.
After a thorough examination of the results for this traffic study, staff came to the
following determination. The 35 mile per hour zone is appropriate for the portion
of Stange Road from Bloomington Road to Kingston Drive. However, the speed
limit along the southern portion of Stange Road, from Kingston Drive to 24th
Street, should be reduced to 25 miles per hour. This is reflective of two defining
characteristics of the roadway; one, of the available departure sight distances at
Aspen Drive and Northridge Parkway, which currently do not provide motorists
with enough time to safely enter onto Stange Road; and two, of the potential
conflicts created by parallel parking maneuvers onto and off of Stange Road from
contiguous parking areas.
Landscaping on Stange Crescent Park
Staff conducted a site visit to the intersection of Stange Road and Northridge Parkway
to address the safety concerns stated in Mr. Pierce's letter. A photo of the landscaping
in question has been provided in Attachment E. Staff measured the approximate height
of the wooden sign to be just over three feet and the height of the three surrounding
shrubs at just under six feet; both measurements were taken from ground surface to top
of the object.
In residential zoning, sight triangle regulations require that objects be no higher than
three feet, however, this does not apply in this area. Accepted engineering standards
call for using an object height of 3.5 feet for the purpose of checking sight distance.
Staff conducted a background study relating to Stange Crescent Park and was able to
find only one document addressing the approval of the sign and surrounding shrubs. In
the developer's agreement for Somerset Subdivision, the sign is referred to as an "entry
feature." According to City Assessor data, this entry feature resides partially on land
owned by the Somerset Association and partially on City right-of-way (see Attachment
D).
Therefore, it is staff's recommendation to first, pertaining to speed limits, reduce
the speed limit on Stange Road to 25 miles per hour from its intersection with
Kingston Road south to its intersection with 24th Street; and second, pertaining
to the landscaping on the Stange Crescent Park, to either direct staff to remove
the sign and surrounding shrubs as requested by Mr. Pierce, or to direct staff to
contact the developer to determine an alternate "entry feature" to be located
elsewhere in Stange Crescent Park.
ALTERNATIVES:
1. Direct the City Attorney to modify the ordinance to change the speed limits along
Stange Road by establishing a 35 mile per hour zone from Bloomington Road to
Kingston Drive, and a 25 mile per hour zone from Kingston Drive to 24th Street.
2. Direct staff to remove the sign and/or any planting located within City right-of-way
that is determined to be a sight obstruction.
3. Direct staff to work the developer of the Somerset Subdivision to find an alternative
design for the "entry feature" in Stange Crescent Park.
4. Reject the changes to the speed limits.
5. Reject any modifications to the landscaping located in Stange Crescent Park.
MANAGER'S RECOMMENDED ACTION:
As the Somerset Subdivision and the Taylor Glenn Subdivision to the north continues to
develop, the areas will become increasingly dense with residents. These density
changes, along with the maturation of street trees along Stange Road, will serve to help
calm future traffic. With respect to the Stange Crescent Park sign and landscaping,
staff feels the more appropriate course of action is to facilitate a discussion with the
developer to modify this entryway feature.
Therefore, it is the recommendation of the City Manager that the City Council adopt
Alternatives No. 1 and No. 3, thereby directing the City Attorney to modify the ordinance
to change the speed limits along Stange Road by establishing a 35 mile per hour zone
from Bloomington Road to Kingston Drive and a 25 mile per hour zone from Kingston
Drive to 24th Street, and to direct staff to work with the developer of Somerset
Subdivision to find an alternative design for the "entry feature" in Stange Crescent Park.
ATTACHMENT A: TRAFFIC STUDY DATA
Data taken in area surrounding Crescent Park (10/31/06 to 11/2/06)
Northbound on Stange Road: Eastside of Crescent Park
34
14%
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27
26 2%
25
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Time of Day
Figure 1
Southbound on Stange Road:Westside of Crescent Park
35
16%
34
14%
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Time of Day
Figure 2
(Continued from previous page)
Estimated Average Delay: Northbound on Stange Road
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Time of Day
Figure 3
Estimated Average Delay: Southbound on Stange Road
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Time of Day �
Figure 4
ATTACHMENT B: DEFINITION OF KEY TERMS
1 . 85th Percentile Speed: Is defined as the speed at which 85% of vehicular traffic
is traveling, or slower.
2. Pace: Is the 10 miles per hour range that the largest number of vehicles is
traveling in.
3. Average Daily Traffic ADT : Is the total daily average volume of traffic as
taken over the extent of the study.
4. Estimated Peak Hour Delay AM/PM: This value is the average estimated
delay, in seconds, a motorist may have to wait for a gap of the appropriate size
that would allow entering the traffic stream on the major roadway from a side
street approach.
5. Level of Service: Is a unit of measure that assesses the operational health of
an intersection or approach as specified in the 2000 Highway Capacity Manual
(HCM) base upon averaged control delay. A table from the HCM has been
provided below.
Table 1:HCM,4th Addition Exhibit 17-2 w.17-2
ServiceLevel of . • AWSC
intersections111
LOS _ Control Dolay Per Vehicle(sec}
A _<_10
B >10 and <_15
C >15 and _<25
D >25 and _<35
E >35 and <_50
F >50
TWSC=Two Way Stop Control
AWSC=All Way Stop Control
ATTACHMENT C: STANGE ROAD, SPEED LIMIT/ PARKING AREAS
Bloomington Road
NAapoo Roaq
35 MPH Zonel N
Kingston Drive__
Northridge Parkway
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Adjacent Parking
0
CyRide Bus Stop
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N
Bristol Drive
30 MPH Zone
(Proposed
25 MPH Zone)
Camden Drive
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24th Street
24th Street
Speed Limit: Stange Road Stange Road:Areas with Adjacent Parking
ATTACHMENT D: SOMERSET, STANGE CRESCENT PARK
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Existing Park: 2003 Aerial Photos Approved Concept from Developer's
Agreement: Appendix K-5
ATTACHMENT E: SAFETY CONCERN RELATED TO LANDSCAPING
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Figure 5: Landscaping on Stange Crescent Park