of Northville has a plan to prioritize road repair and replacement
There’s a science to determining how roads should be
repaired or replaced, balanced by practicality and
The process of evaluation and
analysis starts with rating roads using the Pavement
Surface Evaluation and Rating (PASER) system, an
industry-standard assessment in which trained analysts
drive each segment of road (from intersection to
intersection) and score it from one (the worst) to 10 (a
new road). Roads rated 7 or 8 may require routine
maintenance, such as crack sealing or minor patching.
Roads rated 4-6 are considered to be in “fair” condition
and may need preventive maintenance, such as an overlay
or joint repairs. Roads rated less than 4 are candidates
for extensive repairs or reconstruction.
each segment is rated, Roadsoft, a pavement management
software, is used to define the type of repair, its cost
and the allocated budget, to determine the most
cost-effective way to attain the best overall condition
for the roadway network (roads owned by the City). The
software also defines how many lane miles of each type
of repair must be done to attain the long-term condition
goals for the roadway network. The City aims to attain
an average rating of 6 OCI (Overall Condition Index)
with millage funding.
To determine which roads
are the best candidates for the extensive repairs, a
Network Priority Rating (NPR) is calculated for each
pavement segment. Calculations are based on these five
factors: PASER rating, pavement priority, pavement use,
segment length, and pavement classification.
Pavement Priority is classified as: 1)
low – only residential and mostly local residents; 2)
medium – periodic commercial, frequent residential
traffic; and 3) high – frequent commercial and high use
of local traffic.
has four categories: major residential, major commercial
and local residential and local commercial. It is
related to the location, degree of utilization and
expected traffic type/frequency of a particular road
Segment length uses
calculations developed by the state in its Roadsoft
– There are basically five categories: 1) asphalt
standard duty, 2) asphalt heavy duty, 3) concrete
standard duty, 4) concrete heavy duty, and 5) asphalt
overlay composite (asphalt over concrete). Standard vs.
heavy-duty is based in part on the thickness of the
Once the NPR is calculated, all
segments that are candidates for a particular treatment
are determined, based on pavement type (asphalt,
concrete, or composite) and PASER rating. These segments
are then evaluated using NPR to determine a rating, with
the highest values given top priority. Segments are then
chosen for repair until reaching the total lane miles of
treatment recommended in a particular year.
example, this shows one year of the City’s long-term
|Type of road
||3” Mill and Overlay
||3” Mill and Overlay
Types of repairs that will improve the road
Upgrades to roads include
reconstruction, mill and overlay, and crack seal repairs
for roads made of asphalt, composite and concrete.
Reconstruction is a complete tear-down and rebuild; mill
and overlay is a process of grinding down the top layer
– the wearing layer – and setting down new layers of
material (allowing the base of the road to last longer);
and crack-seal repairs are used to apply asphalt to a
crack to prevent water from seeping into the pavement
and potentially creating a pothole.
scheduling repairs or replacement, practical aspects
must be taken into account. For example, when major
water main or sewer work is scheduled in a given year,
major road repairs on that same section of road would be
made immediately following that repair.
streets to be repaired are determined for each year, a
manual review is conducted to balance the location of
repairs with other construction planned or underway
(e.g. construction of new homes or a commercial
building). That way, repairs don’t create gridlock in
one part of town. With proper planning, multiple repairs
can be done sequentially.
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