How to recognize a fatigue-related crash?

Unlike the situation with alcohol-related crashes, no blood, breath, or other measurable test is currently available to quantify levels of sleepiness at a crash site. Thus current understanding of typical crash related characteristics come largely from inferential evidence.

In the United Kingdom, fatigue related crashes have been identified using the following criteria:

The vehicle has run off the road and/or collided with another vehicle or object
There is an absence of skid marks or braking
The driver could see the point of run-off or the object hit prior to the crash
Other causes are eliminated e.g. mechanical defect, speeding, excess alcohol, bad weather; and
Witnesses may report lane drifting prior to the crash [49][50]

Similarly in the United States, the Expert Panel on Driver Fatigue and Sleepiness [79] characterises a fatigue-related crash as follows:

The problem occurs during late night/ early morning or mid-afternoon
The crash is likely to be serious
A single vehicle leaves the roadway
The crash occurs on a high-speed road
The driver does not attempt to avoid a crash
The driver is alone in the vehicle