HomeMy WebLinkAboutA001 - Council Action Form dated August 23, 1994 COUNCIL ACTION FORM
Item #
Date: Au u 3 1994
SUBJECT: Speed limit on South 16th Street and the U.S. Highway 30/Dayton Avenue
overpass.
BACKGROUND:
In the past several weeks, the Iowa Department of Transportation (IDOT) has opened
the new interchange at the Dayton Avenue/U.S. Highway 30 intersection. This has
introduced new traffic on the recently paved South 16th Street section from the U.S.
Highway 30 overpass to Dayton Avenue. With this traffic volume, IDOT officials have
requested that the City post a speed limit along the newly improved South 16th Street
section from the U.S. Highway 30 overpass to Dayton Avenue, and on the U.S.
Highway 30 overpass for safety and liability reasons. Currently, no speed limit is
designated along these streets.
After conducting a speed study, on South 16th Street from the U.S. Highway 30
overpass to Dayton Avenue, staff believes that a 40 mph speed limit should be
designated along this section of South 16th Street. This speed limit is consistent with
prevailing speeds, and the roadway design speeds. This study has included a speed
survey of 137 vehicles in which the average speed was 38 mph, and the 85% speed
was 42 mph. The 85% speed limit is the speed which traffic engineering standards
suggest that speed limits should be posted. At this speed, prudent drivers feel that they
can drive safely under the existing conditions.
Staff also believes that a 40 mph speed limit should also be posted due to the vertical
curves along this section of street. These curves were designed for a 40 mph stopping
sight distance. With this design, motorists proceeding at 40 mph have adequate
stopping sight distance when hazards are encountered.
Iowa DOT officials also indicate that the U.S. Highway 30 overpass is within City limits
and the City has responsibility for designating speed limits on this street section. Since
the street design for this section of street is 35 mph due to the sharp vertical curve on
the overpass structure, staff believes that the speed limit should be 35 mph. This will
enhance safety since motorists on the overpass will have adequate safe stopping
distance to react to turning vehicles on the off-ramps.
CAF - S. 16th St.
August 23, 1994
Page 2
ALTERNATIVES:
1. Designate a 40 mph speed limit on South 16th Street from the U.S. Highway 30
overpass to Dayton Avenue and a 35 mph speed limit on the U.S. Highway 30
overpass.
2. Designate other than a 40 mph speed limit on this section of South 16th Street.
3. Do nothing.
MANAGER'S RECOMMENDED ACTION:
It is recommended by the City Manager that the City Council adopt alternative number 1
above, thereby directing the City Attorney to draft an ordinance designating a 40 mph
speed limit on South 16th Street from the U.S. Highway 30 overpass to Dayton Avenue
and a 35 mph speed limit on the U.S. Highway 30 overpass.
COUNCIL ACTION:
S . 16th Street
U. S . Highway 30 / Dayton Overpass
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Proposed Speed Limits
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Proposed 40 MPH
Speed Zone '
1312'
-- 2640' ---
_ _ S. 16th Street
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City Limits
U.S. Highway 30
--------------------------------
U.S. Highway 30 Proposed 35 MPH
Overpass �` Speed Zone
IDOT Right of Way Line