Research Studies & Reports

DMV’s Research & Development Branch has been conducting research and producing studies and reports since the 1950s. Research & Development reports help DMV to measure the impact of new laws on making drivers safer. We also identify areas where we can improve our processes, explore new approaches to solving existing problems, and branch out into new opportunities to serve you better. 

Request printed copies of studies and reports by mail at:

Department of Motor Vehicles
Research and Development Branch
2415 1st Ave. Mail Station: F-126
Sacramento, CA 95818
(916) 914-8125

Please include the report number, the number of copies requested, and your name, address, and phone number.

393 Results

Report ID Date Published Title Section Links
207 2004/ 01

Teenage Driver Risks and Interventions

By: Scott V. Masten

California teenage drivers aged 16-19-years-old have extremely high per capita and mileage-adjusted crash and traffic violation rates. This report summarizes the literature regarding the risk factors involved in their high crash rates, as well as the countermeasures that have been used in California and elsewhere to reduce their high crash risk. Although some portion of teenage crash involvements can be accounted for by poorer basic vehicle handling skills, the research suggests that it is young drivers’ immaturity and inexperience, and the resultant risk-taking, that contribute most to their increased crash risk. Certain driving conditions, such as nighttime driving and transporting young passengers, are particularly high risk for teen drivers. The higher crash rates for teens associated with the use of alcohol and drugs may mostly be the result of a general pattern of risky behavior. The countermeasures used to reduce the crash risk of teen drivers that are discussed in this report include driver improvement programs, driver education and training, special licensing programs for teens (provisional and graduated licensing), BAC limits, and curfew laws.

206 2004/ 01


By: Helen N. Tashima and Clifford J. Helander

In this thirteenth annual legislatively mandated report, 2001 and 2002 DUI data from diverse sources were compiled and cross-referenced for the purpose of developing a single comprehensive DUI data reference and monitoring system. This report presents crosstabulated information on DUI arrests, convictions, court sanctions, administrative actions and alcoholinvolved accidents. In addition, this report provides 1-year proportions of DUI recidivism and accident rates for first and second DUI offenders arrested in each year over a time period of twelve years. Also, the long-term recidivism curves of the cumulative proportions of DUI reoffenses are shown for all DUI offenders arrested in 1994. Analyses were conducted on the effectiveness of alcohol education programs upon the 1-year postconviction records of those convicted of the reduced charge of alcohol-related reckless driving, and on the effectiveness of the 3-month versus 6-month alcohol education programs on the 1-year postconviction records of first offenders.

205 2003/ 05

Evaluation of California’s Graduated Driver Licensing Program

By: Scott V. Masten and Robert A. Hagge

California’s 1998 graduated driver licensing program was implemented to reduce the high crash risk of teenage drivers. Monthly per capita crash rates for 15-to-17-year-olds were analyzed using time series analysis. No overall reduction in total crashes or fatal/injury crashes was found immediately following program implementation or beginning 6 months later. The 12-month nighttime restriction was associated with significant sudden-permanent reductions of 0.44% in total crashes and marginally significant 0.45%in nighttime fatal/injury crashes. The 6-month passenger restriction was associated with reductions of 2.52% and 6.43% in total and fatal/injury teen passenger crashes, respectively. The fact that no overall reductions in crashes, and only small reductions in crashes associated with the restrictions, were found isnot surprising given findings that teens and parents were either already practicing program requirementsprior to implementation, or not fully complying with the program requirements afterwards. The findings provide support for passenger and nighttime restrictions.

204 2003/ 10

An Inventory of California Driver Accident Risk Factors

By: Michael A. Gebers

This report updates information on a random sample of licensed California drivers as published in an earlier report prepared by the California Department of Motor Vehicles: An inventory of California driver accident risk factors (Gebers & Peck, 1994). It is designed to provide highway safety administrators, insurance industry representatives, and researchers in the field of traffic safety with information for developing program and policy decisions. This report presents driver record information on a random sample of over 200,000 California drivers and driver record histories over varying time periods. The report addresses the following issues related to the assessment of traffic accident risk: • Driver record in relation to gender and age. • Accident-repeater phenomenon. • Relationship between traffic accidents and citations. • Relationship between traffic accidents and multiple driver record variables (e.g., prior accidents and citations, sex, and license class). • Multiple logistic and negative binomial regression equations of accident risk factors and relativities. Findings presented in the report confirmed that prior total citation frequency continues to be the most significant predictor of accident involvement, followed by prior accident involvement frequency. Increased accident involvement was shown to be associated with increased prior citation and accident frequencies, possessing a commercial driver license, being young, being male, having a medical condition on record, and having a physician referral for low visual-acuity on record.

203 2003/ 04

The Effectiveness of Home-Study Driver Education Compared toClassroom Instruction: The Impact on Student Knowledge, Skills, andAttitudes

By: Scott V. Masten and Eric A. Chapman

Home-study driver education programs exist in several states, but none have been scientificallyevaluated to determine if such courses are as effective as classroom-based courses for teaching driver education. Almost 1,500 students were randomly assigned to receive classroom instruction, a CDROM home-study course, a workbook home-study course, or an internet/workbook home-studycourse. Few differences were found on exit exam knowledge and attitude scores, but tended to favor the CD and internet/workbook home-study courses over the workbook or classroom courses.Differences favoring classroom courses on department written test outcomes likely reflect bias in such courses towards teaching test-specific material. The findings present no compelling evidence that home-study courses are less effective than classroom courses for teaching driver education. Thefindings could result in more widespread use of home-study courses. The use of low-cost home-study courses as the first stage of a two-tiered driver education program could make such programs more feasible and acceptable to the public.

202 2003/ 03

Development and Evaluation of a Risk Management Strategy for Reducing Crash Risk

By: Michael A. Gebers and Raymond C. Peck

The goal of this project was to develop a strategy for maximizing the number of traffic crashes prevented by tailoring educational, rehabilitative, and license control interventions to identifiable high-risk problem driver groups. Regression models were applied to a random sample of licensed California drivers with the objective of identifying groups of drivers with elevated risks of being involved in future traffic crashes. The driving records of the risk groups identified from the models were examined to identify drivers not receiving any form of driver improvement or license control actions. The risk levels of these identified "untreated" drivers were compared with negligent operators who have received licensing actions to determine how existing discretionary and mandatory actions correlate with traffic safety risk. The defining characteristics of high-risk drivers escaping driver improvement or license control actions were examined in an attempt to construct a recommended set of countermeasures. The potential utility of these countermeasures in terms of crash reduction and benefit-cost ratios was estimated based on prior research evidence and mathematical simulation. In examining the defining characteristics of high-risk groups that currently escape driver improvement interventions, the majority was characterized either by TVS dismissals, citations, or crashes. These elements often combine with each other and with other risk factors to increase crash risk beyond that of drivers who meet the state’s prima facie definition of a "negligent operator." It is noted that there are two fundamental considerations for constructing a countermeasure system: (1) the countermeasures must be economically and operationally feasible, and (2) they must be legally permissible. Therefore, this study recommends interventions involving minimal expense, no in-person contact with DMV personnel, and no license-control actions.

201 2003/ 01

Comparison of Accident and Conviction Rates for Commercial Drivers Tested Under the Employer Testing Program and Commercial Drivers Tested by DMV

By: Eric Chapman

The Employer Testing Program (ETP) allows eligible employers to conduct drive tests and issue the Certificate of Driving Skills (DL 170) to commercial vehicle operators they employ. To participate in the program, an employer must demonstrate that their driving test and examiners meet standards set by DMV. Employers in the program are subject to annual inspections and audits by the department’s Intrastate Audits Unit. If any deficiencies on the part of the employer are found, the department may impose restrictions ranging from warning letters to revocation or cancellation of the employer’s testing authorization. Approximately 980 employers participate in this program, 60% of which are in the government sector (e.g., fire departments and Caltrans). To help in monitoring the program, the department’s Research and Development Branch compared the driving records of licensed commercial drivers tested under the ETP to commercial drivers tested by DMV. The remainder of this paper presents the methods and results of the driver record analyses and a discussion of the findings.

200 2002/ 11

An Examination of the Characteristics and Traffic Risk of Drivers Suspended/Revoked for Different Reasons

By: Michael A. Gebers and David J. DeYoung

One measure that has traditionally been used to better control drunk and other high-risk drivers has been to suspend or revoke their privilege to drive. However, because the driving privilege is so highly valued, an increasing number of new laws have been passed which prescribe license suspension/revocation as a punishment for a variety of offenses, including some completely unrelated to driving. This has created a diverse group of suspended/revoked drivers. Prior research has demonstrated that suspended/revoked drivers pose a significant traffic risk, but until now little has been known about whether, and if so how, this risk varies as a function of the reason for suspension/revocation. This study classifies suspended/revoked drivers into subgroups based on their reason for suspension/revocation, and then develops demographic and driving risk profiles for each group. Separate risk profiles are developed for the following traffic safety indicators, measured 3 years prior to the suspension/revocation action; 1) total crashes, 2) fatal/injury crashes, 3) total traffic convictions, and 4) total incidents (crashes + convictions). The findings clearly show that: 1) suspended/revoked drivers are a heterogeneous group, both demographically and in their driving behavior; 2) some suspended drivers, such as those suspended/revoked for a non-driving offense, have low traffic risks that are comparable to those of validlylicensed drivers, and; 3) all suspended groups have elevated crash and conviction rates, compared to validly-licensed drivers. The implications of these findings for current laws and policies targeting suspended/revoked drivers are discussed, and recommendations for improving these laws/policies are presented.

199 2002/ 11

Application of Behavior Change Theory to the Development of an Enhanced California Negligent Operator Treatment and Evaluation System

By: Robert A. Roberts

Through this critical review of the literature and evaluation of warning letter contents, the foundation has been set for the development of an enhanced negligent-operator treatment and evaluation system (ENOTES) for California. Criteria to evaluate the treatment letters were developed from the 16 components of the Transtheoretical Model (TTM) of behavior change that, incidentally, incorporates the majority of the recommendations made by traffic safety researchers over the past 50 years. The evaluated studies were tabulated by the strength of the evidence supporting each treatment in terms of the quality of the research and the validity of the methods as defined by the degree to which they reflected components of the TTM. Overall, the research designs were outstanding. However, the warning letters themselves were weaker, and generally not strongly tied to a theory of behavior change. On average, 2.5 of the six General Stage, 1.8 of the five Early Stage, and 0.29 of the five Late Stage TTM elements were utilized. No balanced treatment letters were identified that incorporated the majority of the TTM elements available from all three stages. A definite opportunity exists to strengthen the effectiveness of letter treatments through intelligent use of the TTM

198 2003/ 01


By: Helen N. Tashima and Clifford J. Helander

In this twelfth annual legislatively mandated report, 2000 and 2001 DUI data from diverse sources were compiled and cross-referenced for the purpose of developing a single comprehensive DUI data reference and monitoring system. This report presents crosstabulated information on DUI arrests, convictions, court sanctions, administrative actions and alcoholinvolved accidents. In addition, this report provides an evaluation of the effectiveness of alternative court and administrative sanctions (including alcohol treatment programs and license actions) upon the 1-year postconviction records of first and second DUI offenders over a time period of eleven years. The postconviction driving records of second DUI offenders arrested in 1998 and 2000 were evaluated for 3- and 1-year periods, respectively. Additional analyses were conducted on the effectiveness of alcohol education programs upon the 1-year post conviction records of those convicted of the reduced charge of alcohol-related reckless driving, and on the effectiveness of the 3-month versus 6-month alcohol education programs on the 1-year post conviction records of first offenders.