Three things determine pavement condition ratings: the type of defect present, the severity of the defect and the impact this defect has on roadway surfaces.
There are multiple types of pavement defects, all of which vary in severity and extent, as well as the best method to fix the issue.
Pavement condition ratings only apply to the traveled surface of a road. These ratings do not include the shoulder of the road or other adjacent surfaces. Issues related to drainage, shoulder condition and so forth are recorded separately from pavement condition ratings. Intersections may or may not be included for rating purposes. Some agencies choose to rate intersections separately.
Predominate Severity & Finite Value
There are two ways to determine condition ratings. One is to identify the predominant severity of each defect, and the other is to take note of all defect types observed. These observations are then recorded using finite value or standardized ranges of values.
If going with the predominant severity route, make sure to only specify the main defect with the highest rated severity. The reason for this is to create a rating that represents the typical condition of a particular segment of roadway.
If you are recording the severity of each defect, you will record every defect with its own rating. Use the finite value (the actual percentage) of the extent for each severity category; use of ranges will likely result in too great an extent.
Rating Roads By Foot Or Vehicle
Roads are either rated by foot or by vehicle. In more urban locations it is more common to rate the road by foot. When using a vehicle, drive between 2 and 5 miles per hour in order to take in all necessary observations.
Generally only one lane is used due to budget and time constraints. But, if there is enough time and room in the budget, more than one lane can be used. If lanes are rated individually you will need to use different forms and enter data into the database as multilane segments.
Typically, different values arise from walking or driving. It’s important that these differences are noted and acknowledged to prevent problems that arise when comparing results that were obtained using two different methods.
Obstacles That May Impact Results
The time of year and the current weather will impact the visibility and severity of roadway distress. Moisture and temperature tend to create the greatest discrepancies of all. Observing roadways at the same time each year, and only when surfaces are dry, is the best way to get an accurate calculation.
Other obstacles that could change ratings are the relative sun angle and the direction you view the roadway surface from. The pavement should be inspected from every direction throughout the survey in order to avoid making mistakes or missing important issues.
Make sure to observe the entire area of the traveled roadway segment in order to get a complete picture of defect severities and their overall impact on the road.
Assigning a rating to the width of cracks includes using the average width as opposed to the widest part of the crack. Cracks typically have different widths throughout, but the goal is to obtain the overall severity of the crack. This is best done through finding the average width.
Composite pavement cracks that correspond with concrete joints are classified as distresses. Other cracks are classified by their type, such as transverse or longitudinal.
Additional Information Required
Additional information is often required in order to get the best idea of roadway quality. Historical information about the road, physical appearances, new segments or previous repairs may need to be identified.
Putting The Pieces Together
After thorough inspection, there are three main elements taken into consideration in order to create a pavement condition rating.
- What type of defect(s) is present?
- How severe is this defect? Low, medium, or high?
- How much is the roadway impacted by this defect?
Low severity defects that create little to no impact on roadway quality may simply require a quick patch or overlay coat to prevent worsening of the problem. The sooner issues are identified the more cost effective the available options are. This is why it’s highly recommended to have roadways inspected on an annual basis.