Cracking caused by the asphalt layer flexing under every passing axle until it fails, usually starting at the bottom of the layer and working up. It shows first as parallel longitudinal cracks in the wheel path, then links up into many-sided blocks that look like alligator hide. It signals a structural problem, such as an asphalt layer too thin for the traffic or a weak, wet base, so a thin overlay will not hold it for long.
That's fatigue cracking all through the right wheel path, full-depth patch it, an overlay will just crack right back through.
Also heard as
- alligator cracking
- gator cracking
Do not mix it up with
- Thermal cracking: Thermal cracks run straight across the lane at intervals from cold shrinkage, not in a web inside the wheel path.
Related terms
Rutting
Channel-shaped depressions that form in the wheel paths as the pavement deforms under repeated loads.
Reflective cracking
Cracks in an overlay that mirror the cracks or joints in the old pavement underneath.
Pothole
A bowl-shaped hole through the pavement surface where pieces of asphalt have broken out.
Density
How tightly a compacted asphalt layer is packed, reported as a percentage of its maximum theoretical density.