Carter Road Speed Limit_32nd St_Kane StreetTHE CITY QF
DUB E
Masterpiece on the Mississippi
TO: The Honorable Mayor and City Council Members
FROM: Michael C. Van Milligen, City Manager
SUBJECT: Carter Road, Between West 32nd Street and Kane Street
Speed Limit
DATE: June 12, 2008
Dubuque
AWlmedcaC~N
i
2007
City Engineer Gus Psihoyos recommends that the speed limit on Carter Road be
increased from 25 mph to 35 mph.
The existing 25 mph speed limit on Carter Road, between West 32"d Street and Kane
Street, with its high violation rates, indicates that the posted speed limit is too low for the
existing roadway conditions.
Time after time, traffic studies have shown that increases in posted speed limits do not
normally result in increased travel speeds on the street. Studies have shown that when
posted speeds are too low for existing conditions, this often leads to greater variations
in speed between slower and faster moving vehicles, which can be a source of
tailgating, and perhaps the cause of crashes.
I concur with the recommendation and respectfully request Mayor and City Council
approval.
;` G,~ ~!
*-~
Michael C. Van Milligen
MCVM/Iw
Attachment
cc: Barry Lindahl, City Attorney
Cindy Steinhauser, Assistant City Manager
Gus Psihoyos, City Engineer
THE CTTY OF Dubuque
~~
DUB E ~'CeC~
Masterpiece on the Mississippi
2007
TO: Michael C. Van Milligen, City Mana
FROM: Gus Psihoyos, City Engineer '
SUBJECT: Carter Road, Between West 32"d Street and Kane Street
Speed Limit
DATE: May 28, 2008
INTRODUCTION
The following is in response to a November 11, 2007 request from Nick Kean,
2918 Arabian Trail, to increase the speed limit on Carter Road from its present
25 miles per hour to 35 miles per hour.
BACKGROUND
The most widely-accepted method of establishing speed limits by the traffic
engineering profession is to post the speed limit at the 85t" percentile speed of
the actual traffic flow. The 85t" percentile is the speed at which 85 percent (85%)
or less of the traffic is driving under normal conditions.
Carter Road is a 40-foot wide collector street in the City's system of street
networks; and as a general rule, such streets are wider and have a higher speed
limit to facilitate the movement of traffic, rather than having traffic short-cut
through local neighborhoods.
In late October of 2007, a citizen called to the Engineering Department and
revealed that the posted speed limit for Carter Road, between West 32"d Street
and Kane Street, was not consistent. Vehicles traveling from West 32"d toward
Kane saw 35 mph speed limit signs, but those vehicles traveling in the opposite
direction, the speed was posted at 25 miles per hour. It is unclear how this
situation came to be or how long it has been like that.
Once the City was notified, the 35 mph speed limit signs were changed to 25
mph to conform to City Code.
Subsequent to changing the signs, several calls were received by Engineering
inquiring as to the reason for the change. Most assumed that the speed limit on
Carter Road was 35 mph for both directions.
Upon receipt of Mr. Kean's letter and subsequent referral from City Council, the
Engineering Department completed a speed study in this corridor.
Due to a number of factors, including weather and other study requests,
equipment was installed on May 14-15 to collect speed data with the following
results:
Carter Road 85th% Speed
Arabian Trail to West 32"d Street
Northeasterly 41.0 mph
Southwesterly 43.3 mph
Kane to Arabian Trail
Northeasterly 36.6 mph
Southwesterly 53.0 mph
Assumed
Violation Dates Posted Violation Posted Violation
Speed Rate Speed Rate
Arabian Trail to West 32"d Street
Northeasterly 25 76.8% 35 17.5%
Southwesterly 25 82.0% 35 22.6%
Kane to Arabian Trail
Northeasterly 25 51.10% 35 68.0%
Southwesterly 25 92.01 % 35 62.5%
Based on previous studies, there should be a significant reduction in speed
violation rates if the speed limit were increased to 35 mph, without an increase in
actual travel speeds on the street. Such a decrease in violation rates should also
require a significantly less speed enforcement effort by the Police Department.
RECOMMENDATION
The existing 25 mph speed limit on Carter Road, between West 32"d Street and
Kane Street, with its high violation rates, indicates that the posted speed limit is
too low for the existing roadway conditions.
Time after time, traffic studies have shown that increases in posted speed limits
do not normally result in increased travel speeds on the street. Studies have
shown that when posted speeds are too low for existing conditions, this often
leads to greater variations in speed between slower and faster moving vehicles,
which can be a source of tailgating, and perhaps the cause of crashes.
ACTION TO BE TAKEN
The City Council is requested to adopt the attached ordinance raising the speed
limit on Carter Road between West 32"d Street and Kane Street from 25 mph to
35 mph.
Prepared by Bill Schlickman, Traffic Engineering Assistant
ORDINANCE NO. 45-08
AN ORDINANCE AMENDING THE CODE OF ORDINANCES OF THE CITY OF
DUBUQUE, IOWA BY REVISING SUBSECTION (C) OF SECTION 32-321.285
THEREOF PROVIDING FOR THE ESTABLISHMENT OF SPEED LIMITS ON
CARTER ROAD
NOW, THEREFORE, BE IT ORDAINED BY THE CITY COUNCIL OF THE
CITY OF DUBUQUE, IOWA:
Section 1. That the Code of Ordinances of the City of Dubuque, Iowa,
be amended by adding the following to Subsection (c) of Section 32-321.285
thereof as follows:
"Sec. 32-321.285. Limits Generally."
(c)
TWENTY-FIVE (25) MILES PER HOUR
Carter Road, from John F. Kennedy Road to Kane Street
THIRTY-FIVE (35) MILES PER HOUR
Carter Road, from Kane Street to West Thirty-Second Street
Passed, approved and adopted this 16th day of June, 2008.
Roy D. Buol, Mayor
Attest:
Jeanne F. Schneider, CMC, City Clerk
Nick Kean
2918 Arabian Trail
556-1869
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