Pavement distresses are abundant. Driving through town, it is easy to spot the three potholes on Main Street, fatigue cracking on Third Avenue, and patch sealing on Elm Street. Pavement distresses are clear signs the road is experiencing wear and tear. And not to mention these can all be hazardous to vehicles and drivers!
Less apparent are the causes of pavement distresses. Vehicle loading, environmental conditions, and construction quality and maintenance are the main classifications of distresses, but most are caused by a combination of the three factors.
RoadWay, RoadBotics’ proprietary road assessment platform, shows images of every 10 feet of road using three main components:
- Rating Score from 1 (no visible signs of fatigue) to 5 (pavement failure).
- Image of the road being assessed in the frame
- Individual Distress Identification highlighting the distresses visible
Using images from RoadWay, let’s look at the causes of six different categories of pavement distresses.
RoadBotics categorizes potholes as potholes and lane shoulder drop off. This image shows a pothole along with alligator cracking (categorized as fatigue cracking) and longitudinal cracking (categorized as transverse/longitudinal cracking).
Potholes are caused by vehicles loading and environmental conditions. Potholes begin with the disintegration of the pavement surface exacerbated by vehicle loading and moisture. The hole becomes larger as the disintegration moves down through pavement layers.
It is important to note that potholes are often formed by severe fatigue cracking, as evident in this image.
Pavement Rating: 5 – Major surface damage due to the fatigue cracking escalating in severity, forming a pothole.
RoadBotics categorizes fatigue cracking as alligator cracking, pictured here, and edge cracking. Alligator cracking is a failure of the pavement surface caused by vehicle loading. It forms interconnected cracks resembling alligator skin and is worsened by inadequate packing of base layers and/or poor drainage.
Pavement Rating: 4 – Emerging critical failure due to the expanse and interconnectedness of the alligator cracking.
RoadBotics categorizes the following distresses as pavement distortions: shoving, rutting, corrugation, depressions, and bumps and sags. This image shows shoving along with slippage cracking (categorized as transverse/longitudinal cracking).
Shoving occurs when vehicle loading causes the pavement to move and bulge, generally parallel to the direction of traffic, with an unstable asphalt layer. It occurs due to a weakened pavement layer, poor bonding between layers, or excessive moisture in the subgrade.
Pavement Rating: 4 – Significant damage and emerging critical failure due to the extent of slippage cracking coupled with shoving.
RoadBotics categorizes raveling/weathering and bleeding as surface deterioration. Raveling/weathering, pictured here, is the disintegration of the pavement surface and can be caused by age, vehicle loading, poor asphalt mix, poor compaction, dust, and moisture.
Pavement Rating: 3 – Appearance of pervasive distress due to the expanse of the raveling/weathering patches, although not severe.
RoadBotics categorizes transverse cracking, longitudinal cracking, block cracking, reflective cracking, and slippage cracking as transverse/longitudinal cracking. This image shows longitudinal cracking which runs parallel to the centerline and direction of traffic.
Longitudinal cracks are caused by a poorly constructed paving lane joint, temperature cycling, reflective cracking in a base layer, or volume changes in subgrade.
Pavement Rating: 3 – Appearance of pervasive distress due to the length and number of longitudinal cracks.
RoadBotics categorizes patches/sealant as hot/cold practhes or seal cracks, pictured here. Although crack sealing is a suitable preventative maintenance measure for transverse/longitudinal cracking, it is considered a pavement distress because over time the cracking will escalate to failure.
Pavement Rating: 3 – Appearance of pervasive distress due to mild crack sealing with the presence of unsealed cracking.