Reference Desk Include

Road RepairsCity 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 traffic flow.

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.

After 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.

Pavement use 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.

Segment length uses calculations developed by the state in its Roadsoft program.

Pavement classification – 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 pavement.

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.

For example, this shows one year of the City’s long-term strategy:

Type of road Repair Lane miles
Asphalt Reconstruction .252
Asphalt 3” Mill and Overlay .256
Asphalt Crack Seal 4.062
Composite 3” Mill and Overlay .418
Composite Crack Seal 1.389
Concrete Asphalt Overlay .330

Types of repairs that will improve the road network
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.

When 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.

Once all 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.

 

 

Back to News