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.
Studies & Reports Sections
Studies and reports are assigned to a Section that best describes the type of report. Click on a section title below to see a short description.
I. Driver Education & Training Studies
II. Driver Licensing Screening Studies
III. Studies on Improvement and Control of Deviant Drivers
IV. Basic Research & Methodological Studies: Driver Performance, Accident Etiology, Prediction Models, and Actuarial Applications
V. Driver Licensing / Control Systems & Safety Management Studies
VI. Studies on Special Driver Populations
VII. Miscellaneous Studies & Reports
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.
| Report ID | Date Published | Title | Section | Links |
|---|---|---|---|---|
| 233 | 2011/ 01 |
2011 ANNUAL REPORT OF THE CALIFORNIA DUI MANAGEMENT INFORMATION SYSTEMIn this twentieth annual legislatively-mandated report, 2008 and 2009 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 alcohol-involved crashes. In addition, this report provides 1-year proportions of DUI recidivism and crash rates for first and second DUI offenders arrested in each year over a time period of 19 years. Also, the long-term recidivism curves of the cumulative proportions of DUI reoffenses are shown for all DUI offenders arrested in 1994. Two analyses were conducted to evaluate if referrals to DUI programs were associated with reductions in 1-year subsequent violations and crashes among those convicted of the reduced charge of alcohol-related reckless driving, and if referrals to the 9-month DUI program were associated with reductions in 1-year subsequent violations and crashes when compared to referrals to the 3-month DUI program among first DUI offenders. The proportions of 2008 convicted first and second offenders who were referred, enrolled, and completed DUI programs are also presented. |
V | |
| 234 | 2011/ 12 |
California’s Three-Tier Driving-Centered Assessment System – Outcome AnalysisThis Outcome Analysis constitutes the second of two reports on the 3-Tier Assessment System, as piloted by California DMV in 2006-2007. It contains (a) a projection of the costs associated with the Area Driving Performance Evaluation, (b) a determination of the willingness of a participant to pay a fee for the Area Driving Performance Evaluation, (c) a determination of the percentage of drivers who were assessed to have a limitation, but who, upon completion of the assessment, were able to retain their driving privileges, (d) the utilization of certified driving rehabilitation specialists, and (e) the results regarding crash rates and retention of driving privileges. Together, these analyses examine the effectiveness of the 3-Tier Assessment System in identifying functional impairments, reducing crashes, and extending safe driving years for California drivers of all ages. These analyses are based upon 2 years of elapsed driving history for the 12,279 customers who participated in the Pilot, along with two control groups: 14,907 customers in the Baseline II cohort, and 10,551 customers in the Nearby cohort. Based on limited data, an estimation is provided of the costs of the anticipated increase in the use of the ADPE, as associated with the 3-Tier Assessment System. Very few customers were willing to pay a fee for the ADPE. The overwhelming majority of customers, even those with functional limitations, were able to retain their driving privilege. No customers reported using certified driving rehabilitation specialists. The analyses found no evidence for a reduction in crash risk subsequent to participation in the Pilot; however, the analyses found some evidence that the Pilot is associated with an increased amount of time to complete the renewal process, with an increase in the odds of failing to renew the driving privilege, and with an increase in the odds of receiving a restricted license. Recommendations regarding implementation and future research are included. |
II | |
| 236 | 2012/ 01 |
2012 ANNUAL REPORT OF THE CALIFORNIA DUI MANAGEMENT INFORMATION SYSTEMIn this twenty-first annual legislatively-mandated report, 2009 and 2010 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 alcohol-involved crashes. In addition, this report provides 1-year proportions of DUI recidivism and crash rates for first and second DUI offenders arrested in each year over a time period of 20 years. Also, the long term recidivism curves of the cumulative proportions of DUI reoffenses are shown for all DUI offenders arrested in 1994. Two analyses were conducted to evaluate if referrals to DUI programs were associated with reductions in 1-year subsequent violations and crashes among those convicted of the reduced charge of alcohol-related reckless driving, and if referrals to the 9-month DUI program were associated with reductions in 1-year subsequent violations and crashes when compared to referrals to the 3-month DUI program among first DUI offenders. The proportions of convicted first and second DUI offenders arrested in 2009, who were referred, enrolled, and completed DUI programs are also presented. |
V | |
| 235 | 2012/ 01 |
An Evaluation of Factors Associated with Variation in DUI Conviction Rates Among California CountiesAlthough California’s statewide driving-under-the-influence of alcohol and/or drugs (DUI) conviction rate has improved over time from 64% in 1989 to 79% in 2006, the DUI conviction rates vary considerably among counties. The purpose of this study was to identify factors associated with differences among California county DUI conviction rates averaged from 2000-2006. The three approaches to obtain information were: (a) surveys sent to California judges, prosecuting attorneys, public and private defense attorneys, and court administrators; (b) face-to-face interviews conducted with California judges, prosecuting attorneys, and public and private defense attorneys; and (c) analyses of various county-level demographic and socioeconomic factors, DUI arrest and conviction process measures, and crash/recidivism variables. It was found that counties with higher DUI arrest rates tend to have lower DUI conviction rates. Counties with high DUI conviction rates tend to convict at lower BAC levels and have higher percentage usage of blood BAC tests. Counties also varied in their alcohol-reckless conviction rates as well as the BAC levels considered appropriate for negotiating alcohol-reckless plea bargains. While the 7-year (2000-2006) statewide average percentage of DUI arrestees convicted of alcohol-reckless driving was 8.1%, county percentages ranged from 0% to 22.6%. Higher prosecution caseload as measured by county violent crime rates isassociated with lower DUI conviction rates, while shorter lengths of time from arrest to conviction are associated with higher DUI conviction rates. Varying prosecution policies were strongly identified by survey respondents as influencing variation in county DUI conviction rates. Convicting for drug-only DUI was considered to be very difficult due to the lack of scientifically based per se levels of drug impairment. Recommendations are made based on these findings. |
III | |
| 237 | 2012/ 05 |
Identifying Barriers to Driving Privilege Reinstatement among California DUI OffendersEvidence suggests that many suspended DUI offenders delay reinstatement of their driving privileges long after they become eligible to reinstate and that those who delay have higher recidivism rates and remain outside of the driver-control system, making corrective action difficult if their driving continues to be a problem. This study updates prior estimates of the extent to which California DUI offenders delay reinstatement of their driving privileges after suspension and investigates the perceived barriers to reinstatement through surveys of offenders and DUI-system professionals. California driver records show that the majority of otherwise reinstatement-eligible 1st and 2ndDUI offenders in California do not reinstate their driving privileges 3 or more years following their arrests. The surveyed offenders and DUI-system professionals indicated strong agreement that high overall financial costs and offenders’ confusion about system requirements are the most significant barriers to meeting the obligations that would enable offenders to reinstate their driving privilege, followed closely by failure to complete DUI Program requirements, most often because of offenders’ inability to pay the program costs, and also because they lack available alternate transportation to attend classes. The barriers to reinstatement may effectivelydeter some offenders from driving, preventing DUI incidents they might otherwise have caused, but appear to deprive others at risk of recidivating who continue to drive impaired from access to needed intervention programs. To address the study’s primary identified barriers to driving privilege reinstatement, several recommendations are made addressing cost mitigation, improved centralized communication of system requirements, and the benefits to obtaining early license restrictionand, ultimately, reinstatement. |
III | |
| 239 | 2012/ 09 |
DIFFERENCES BETWEEN JAIL SENTENCES AND JAIL TERMS ACTUALLY SERVED AMONG DUI OFFENDERS IN SELECTED CALIFORNIA COUNTIESRecords of 32.7% of California’s DUI offenders convicted in 2006, who received jail or a jail alternative sentence, were used to compare jail terms at sentencing to actual jail time served, and to describe used alternative sanctions to jail. County data systems’ variation, tracking methods, quality and completeness of data, and lack of communication between Courts and Sheriff’s Departments limited sample size and representativeness. Percentages of jail time served across participating counties ranged from 0 to 67% for 1st offenders, 0 to 47% for 2nd offenders, and 0 to 67% for 3rd+ offenders. Median percentages of jail sentences actually served across participating counties were 0%, 19%, and 38% for 1st, 2nd, and 3rd+ offenders, respectively. Alternative sentences were used more often on 1 st DUI offenders, less so on 2 nd offenders, and least often on 3 rd offenders. The most popular alternative sentences in lieu of jail options were Sheriff’s Work Program and Caltrans Work Program. Jail sentences reported to DMV greatly overstate amount of jail time actually served by DUI offenders. Further evaluation of effectiveness of jail time served by California DUI offenders is not possible at present because California’s DUI Offender Tracking System does not keep good track of offenders. Recommendations are: results from previous California DMV studies and/or studies from other states showing jail terms as ineffective in reducing alcohol-involved crashes or DUI recidivism should be taken with caution; efforts should be made so California’s DUI Offender Tracking System is consistent with NHTSA’s 2006 guidelines; DMV’s court abstract collection system should require jail terms keyed in, if disposition code “J” is present; DMV’s JAG project to assess accuracy and timeliness of DUI conviction data sent to DMV should be finished, and its findings used in conjunction of this study’s findings to enable the implementation of recommendations from NHTSA’s 2011 California Traffic Records Assessment. |
V | |
| 238 | 2012/ 09 |
ESTIMATION OF FATAL CRASH RATES FOR SUSPENDED/REVOKED AND UNLICENSED DRIVERS IN CALIFORNIAThis study used a quasi-induced exposure (QIE) analysis technique to estimate annual fatal crash involvement rates for S/R, unlicensed, and validly licensed drivers in California from 1987 through 2009 using fatal crash data obtained from National Highway Traffic Safety Administration’s Fatality Analysis Reporting System (FARS) and California Department of Highway Patrol’s Statewide Integrated Traffic Records System (SWITRS). The annual fatal crash involvement ratios range from 0.81 to 0.91 for validly licensed drivers, 1.44 to 4.29 for S/R drivers, and 1.60 to 3.50 for unlicensed drivers, respectively, over the 23-year time period studied. The annual at-fault overinvolvement rates for S/R and unlicensed drivers relative to validly licensed drivers range from 1.57 to 4.93 for the S/R group and from 1.84 to 4.10 for the unlicensed group. Although the annual rates fluctuate, S/R and unlicensed drivers were overinvolved as at-fault drivers in fatal crashes every year relative to validly licensed drivers. The fatal crash involvement ratios obtained for all years combined (1987 through 2009) are 0.86 for validly licensed drivers, 2.23 for S/R drivers, and 2.34 for unlicensed drivers. The at-fault overinvolvement rates for the S/R and unlicensed groups, relative to the validly licensed group, are 2.60 and 2.73, respectively, for this 23-year period. The study results provide strong evidence that S/R and unlicensed drivers are much more hazardous on the road than are validly licensed drivers. Compared to licensed drivers, those who drive without a valid license are nearly three times more likely to cause a fatal crash relative to their exposure. The study findings strongly justify the use of countermeasures, including vehicle impoundment, to control S/R and unlicensed drivers and to reduce crashes caused by these drivers. |
VI | |
| 243 | 2013/ 01 |
2013 ANNUAL REPORT OF THE CALIFORNIA DUI MANAGEMENT INFORMATION SYSTEMIn this twenty-second annual legislatively-mandated report, 2010 and 2011 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 alcohol-involved crashes. In addition, this report provides 1-year proportions of DUI recidivism and crash rates for first and second DUI offenders arrested in each year over a time period of 21 years. Also, the long-term recidivism curves of the cumulative proportions of DUI reoffenses are shown for all DUI offenders arrested in 1994. Two analyses were conducted to evaluate if referrals to DUI programs were associated with reductions in 1-year subsequent violations and crashes among those convicted of the reduced charge of alcohol-related reckless driving, and if referrals to the 9-month DUI program were associated with reductions in 1-year subsequent violations and crashes when compared to referrals to the 3-month DUI program among first DUI offenders. The proportions of convicted first and second DUI offenders arrested in 2010, who were referred, enrolled, and completed DUI programs are also presented. |
V | |
| 242 | 2013/ 02 |
CHANGES IN DRIVER CANNABINOID PREVALENCE ASSOCIATED WITH IMPLEMENTING MEDICAL MARIJUANA LAWS IN 14 U.S. STATESThis study’s objective was to investigate whether implementing medical marijuana laws was associated with changes in cannabinoid prevalence among drivers involved in fatal crashes in California and 13 other states with medical marijuana laws implemented before 2010. Time series ARIMA analyses were used to calculate stateby-state estimates of the percentage-point change in cannabinoid prevalence among fatal-crash-involved drivers associated with implementation or modification of medical marijuana laws. The implementation of medical marijuana laws was found to be reliably associated with increased cannabinoid prevalence in only three states: California, with a 2.1 percentage-point increase in the percentage of all fatal-crash-involved drivers who tested positive for cannabinoids (1.1% pre vs. 3.2% post, which represents a 196% increase in cannabinoid prevalence relative to the pre-law level) and a 5.7 percentage-point increase (1.8% vs. 7.5%, or a 315% increase) among fatally-injured drivers; Hawaii, with a 6.0 percentage-point increase (2.5 vs. 8.5, or a 235% increase) for all drivers and a 9.6 percentage-point increase (4.9% vs. 14.4%, or a 196% increase) among fatally-injured drivers; and Washington, with a 3.4 percentage-point increase (0.7% vs. 4.1%, or a 455% increase) for all drivers and a 4.6 percentage-point increase (1.1% vs. 5.7%, or a 432% increase) among fatally-injured drivers. The increases in all three states were stable step increases, meaning that the prevalence increased to a new level in these states and remained relatively flat subsequently. No relation between the post-law cannabinoid prevalence change estimates and the ease of marijuana access rankings was found. |
VI | |
| 241 | 2013/ 02 |
EVALUATION OF A CONTACT LETTER TO INCREASE LICENSURE AMONG IMPROPERLY LICENSED CALIFORNIA MOTORCYCLE OWNERSThis report presents results of an evaluation of a pilot program intended to increase licensure among improperly licensed California motorcycle owners. The intervention used in this pilot program involved mailing an official DMV contact letter to owners of currently-registered motorcycles who were not properly licensed to ride two-wheeled vehicles. This correspondence informed the recipient of the legal consequences of riding without proper licensure, and provided information regarding how to obtain a motorcycle license in California. Half of the improperly licensed motorcycle owners (n = 33,068) were randomly assigned to be mailed the contact letter. The remainder (n = 32,698) served as a noletter control group. The 33-month subsequent-to-mailing license status and 18-month subsequent-to-mailing driver records for participants in these two groups were compared to determine the effect of the letter on motorcycle licensure, crashes, and violations. The results indicate that the contact letter increased motorcycle licensure among most age groups of owners, but did not affect crash involvements or traffic violations. The contact letter increased the number of previously unlicensed owners who became legal motorcycle operators without increasing their crash or traffic violation rates, but at a total net cost of $25.81 per additional owner who became properly licensed as a result of sending the letters. While the letter treatment significantly increased the motorcycle licensure rate, the overwhelming majority of treated owners in the present study (85.5%) remained improperly licensed to operate two-wheeled vehicles on public roadways, which is consistent with the results from a similar study in Maryland (Braver et al., 2007). Given the relatively low cost of treatment, the increase in motorcycle licensure associated with the letter, and the traffic-safety neutral outcomes, it is recommended that future use of a contact letter for improperly licensed owners be considered if the value of bringing owners into legal licensing status is deemed to be worth the cost of treatment. Future letters may be more effective if they are specifically tailored to the demographic characteristics (e.g., age and sex) of the unlicensed owners. |
VI |