Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Civil Engineering

Major Professor

Shashi S. Nambisan

Committee Members

Asad J. Khattak, Christopher R. Cherry, Russell L. Zaretzki


According to the National Highway Traffic Safety Administration (NHTSA), motor vehicle crashes are the leading cause of death among people aged 1-54 in the United Sates. In 2015, the number of motor-vehicle deaths on U.S. roadways totaled 35,092, a 7% increase from 2014 (32,744). Though lower gas prices and increased vehicle mileage combined with risky driving behaviors (e.g. speeding, driving while texting) account for the increased fatality rate, seatbelt non-use has been a significant contributory factor. It is estimated that nearly half (48%) of passenger vehicle occupants involved in fatal crashes each year are unrestrained.

In a recent 2014 report released by the Tennessee Department of Transportation, failure to use seatbelt by passengers was cited as one of the major contributory factors in fatal and serious injury crashes, placing second to “roadway departure” crash incidences. Promoting the use of seatbelts among the motoring public requires significant efforts. Changing habits across the society often takes decades; however, concerted programs can expedite this transformation. Many studies on daytime seatbelt evaluations have demonstrated that these programs are effective in that regard, however similar efforts for nighttime evaluations are limited.

This dissertation investigated the immediate and longer term impacts (up to six months) of enforcement and education programs on nighttime seatbelt usage for front-seat vehicle occupants. Through examinations of both stated and revealed behaviors, the outcomes pertaining to seatbelt usage and related motor vehicle safety activities were addressed. Using a longitudinal data (nighttime seatbelt observations and interview surveys) collected in six counties in East (sites where interventions implemented) and Middle (as control sites) Tennessee from March 2015 to November 2016, descriptive and statistical analyses were perform to evaluate seatbelt usage before-and-after several intervention programs were implemented. Sound statistical techniques including Generalized Estimating Equations and Bivariate Probit models were utilized in the model framework.

Overall, the results of the study show that intervention programs such as saturation patrols, Click-It-Or-Ticket campaigns combined with paid or earned media education programs are more effective at increasing nighttime seatbelt use in the short term, however, the effectiveness decay with time if the programs are not sustained regularly.

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