Civil and Environmental Engineering


Date of this Version



Mohlman, C. (2013). Driver fatigue enforcement techniques and their effect on crashes (Master's thesis). University of Nebraska-Lincoln, Lincoln, NE.


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Civil Engineering, Under the Supervision of Professor Aemal Khattak. Lincoln, Nebraska: July, 2013

Copyright (c) 2013 Carrie Mohlman


Fatigued driving is a type of driver impairment caused by a lack of sleep, sleep disorders, long drive times, etc. Fatigued driving enforcement aims to improve safety by removing impaired drivers from the roadway. While fatigued driving is detrimental to safety, there exists the issue of identifying fatigue. There is a range between being awake and asleep and, in order to improve safety, enforcement officers must be able to identify the point at which drivers are impaired.

This thesis investigates potentially effective fatigued driving enforcement techniques for use by enforcement officers. These techniques were investigated through three primary means: a literature review, a nationwide telephone survey, and a statistical estimation of crash models. The telephone survey was administered to state patrol agencies across the United States. It collected information related to fatigued driving policies and procedures. The collected data were coded into a spreadsheet and analyzed using statistical models of fatigue-involved crashes.

Three fatigue-involved crash models were estimated with data from the telephone survey and crash databases. Two crash frequency models were estimated. Both were negative binomial models and used the sum of fatigue-involved crashes over a certain time period as the dependent variable. The first crash frequency model only considered fatigue-involved fatal crashes while the second considered all fatigue-involved crashes. A crash severity model was estimated as well.

The crash models provided evidence that certain fatigued driving enforcement techniques had a positive impact on roadway safety. States with fatigued driving related law enforcement training and driver education programs tended to be safer than those that did not have such programs. The technique shown to have the greatest impact on fatigue related safety was the use of driving cues to determine if a driver was fatigued. This was the only technique significant in two crash models. The use of driving cues to identify fatigued driving appears to be an effective method for improving safety. Further research is necessary to better understand the issue of fatigued driving and to objectively identify fatigue.

Advisor: Aemal Khattak