Memo - 2006 Street Reconstruction
Public Warks Depmiment
Memorandum
TO: Honorable Mayor and Council Members
COPY: Rick Getschow, City Manager
FROM: John R. Bradford, P.E., Assistant City Engineerjf!3
DATE: December 13, 2005
SUBJECT: 2006 Street Reconstruction
We are bringing discussions regarding the 2006 Street Reconstruction project to the work
session for your consideration. The first is curb and gutter and the second is the
assessment methodology.
Curb and Gutter
The 2006 Street Reconstruction project area includes 18t!" 19th and 20th Avenues South
between Main and Excelsior Boulevard and 1 st Street South. between 17'h and 18th
A venues. This area does not currently have curb and gutter and we are proposing to
install it with the project.
Why is Curb and Gutter important?
There are two essential functions curb and gutter. Both are interrelated and increase the
long-term durability of the pavement.
The first is to provide edge protection for the asphalt pavement. This is especially
important at intersections and areas where on street parking occurs. Invariably, a number
of vehicles will cut the corner or park off the pavement. Over time this leads to the
corner edge of the pavement breaking off and deterioration of the unpaved area adjacent
to the street. The broken edge provides a weak spot for further degradation of the
pavement.
The second purpose of curb and gutter is to convey storm water away from the street and
into the storm sewer system. The curb section gives a solid barrier to prevent erosion
from occurring at the pavement edge. Besides being unsightly, the erosion at the edge
leads to puddles forming next to the pavement.
.
.
.
The depressions left by tire tracks and edge erosion fill with w~ter which then percolates
under the pavement and significantly weakens the structure.
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Failed pavements caused by a weak pavement structure
The City policy regarding curb and gutter installation in areas that do not already have it
allows neighborhoods to opt out if 55% of the effected residents file a petition stating
their request.
Where ClUb is not installed, the City addressed the problems enumerated above by using
a thicker asphalt section at the edge of the pavement and installing edge drain to deal with
the ponding. The edge drain effectively pulls water out from under the pavement and
should be considered on all newly reconstructed streets in the future regardless of curb
and gutter.
The thickened edge solution, however, provides no edge protection and a minimal
strength increase. Additionally, this solution provides a significant challenge to the
contractor and results in higher cost without a reciprocal benefit.
We propose to change the standard detail for streets without curb and gutter. The new
detail includes an 18" concrete edge pavement on each side of the street. This will
provide the edge protection and strength needed to address the challenges of a rural
section street.
Concrete
Pavement
Asphalt Pavement
Class V Aggregate
Concrete Edge Pavement
The edge pavement is not a curb and gutter. It matches the grade and cross slope of the
pavement. The City of Excelsior requires this in all new rural section streets. The Opus
Complex in Minnetonka has also installed this pavement section. Maplewood also uses a
similar detail.
The purpose of changing the design is twofold. First, and most importantly, constructing
long lasting pavements is in the City's best interests and this is a significant improvement
to the current rural pavement design. The City's interest is long term cost reduction
while the resident's primary interest is typically short term cost. In addition to providing
long term cost savings, the concrete edge pavement will reduce the financial incentive for
residents to opt out of the curb and gutter program, as the cost of concrete edge pavement
is only slightly less than the cost of curb and gutter.
Assessments
We are proposing to divide the project area into two assessment zones. Please see the
attached map.
The first zone encompasses the area on 18th and 19th Avenues between 1 st Street South
and Excelsior Boulevard. We are proposing to assess on a Unit Basis in this area. In
1999, cul-de-sacs were constructed at the southern ends of these avenues. None of the
abutting property owners were assessed for this improvement.
A front footage methodology would eliminate the cul-de-sac properties from the
assessment because they do not directly abut the project area. However, they gain equal
benefit from the project. Additionally, the properties north of the cul-de-sacs would see a
decrease in their assessment amounts and have equal benefit of the cul-de-sac and the
project. It therefore seems equitable to assess them together on a unit basis.
The remaining project area will be assessed on a front footage basis. We anticipate being
able to present some preliminary assessment rates at the work session.
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