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Synthesis of Studies That Relate Amount of Enforcement to Magnitude Of Safety Outcomes

The National Cooperative Research and Evaluation Program (NCREP) identifies and funds research and evaluation projects that improve and expand State highway safety countermeasures. One such topic is measuring the impact of various amounts of traffic enforcement on changes in safety outcomes. The project team identified 80 relevant studies for inclusion in the synthesis. Current literature only supported findings related to occupant protection enforcement. No relationship between levels of enforcement and safety outcomes could be identified for distracted driving, alcohol-impaired driving, speeding, or aggressive driving. However, for all targeted behaviors, the enforcement campaigns evaluated were effective in improving safety outcomes even though the combination of these evaluations could not provide sufficient evidence to establish a relationship between the level of resources used and the magnitude of the safety improvement.

Research on Older Adults’ Mobility: 2021 Summary Report

This report summarizes a meeting to spotlight research on older adults’ mobility held in January 2021– dubbed ROAM, Research on Older Adult Mobility – provided a forum to share news of completed research, report on the progress of ongoing studies, and highlight priorities for future work. Participants included medical professionals, occupational therapists, State DMV officials, mobility service provider specialists, automated driving system/advanced driver assistance system experts, and other academic and private sector research professionals. The meeting supported equity in traffic safety as it addressed disparities faced by older adults.

Visual Scanning Training for Older Drivers

This study examined the effectiveness of a visual scanning training program administered by an occupational therapist as an intervention to improve visual scanning performance of healthy older drivers. Participants included 89 licensed drivers age 70 and older. The training program consisted of four, 1-hour sessions. Participants completed three on-road evaluations: pre-intervention, immediately post-intervention, and 3 months post-intervention. During the evaluations a camera recorded driver face video to support later analyses of the frequency, duration, and direction of eye glances away from the forward line of sight. Analyses of driving data showed no significant differences between intervention and control groups on driving or glance measures.

Estimating Motorcycle Miles Travelled from State Vehicle Inspection Records

This report summarizes a study that examined motorcycle miles traveled as indicated by odometer readings taken from vehicle inspection records. Estimating vehicle exposure is difficult for any type of vehicle, and motorcycles are no exception. Motorcycle vehicle miles traveled (VMT) is based on traffic counts of sampled roadways supplemented with traffic modeling. This study sought to improve understanding by examining motorcycle odometer readings as measures of VMT in Hawaii, North Carolina, and Virginia. Results showed mean annual mileage per motorcycle was consistent year-to-year, and motorcycles were ridden about 2,000 miles each year.

Drug Testing and Traffic Safety: What You Need to Know

Drugged driving is both of great interest and very complex. This report continues that discussion by examining how drug use data from people involved in a motor vehicle crashes is entered into NHTSA’s Fatality Analysis Reporting System (FARS), a cornerstone of NHTSA's information collection systems. It has given Federal and State agencies, legislators, advocacy groups, and researchers key data about fatal motor vehicle crashes for all road user types and on all public roads. It is internationally respected for its breadth and depth of data. But reporting drug use across a myriad of substances, and with varying testing protocols across forensic laboratories and across States can lead to confusion about the meaning of results. Currently, the limitations described in this report constrain interpretation of drug test results data, including comparisons across jurisdictions or years. In some other research areas with missing or incomplete data, estimates may still be useful. This is not the case with FARS drug data. The report discusses NHTSA’s actions for improving the quantity and quality of drug data in FARS.

Characteristics of State Law Enforcement Liaison Programs

This study increased understanding of State law enforcement liaison (LEL) programs by describing their characteristics, duties, responsibilities, and activities. It included an online survey of LELs and their State Highway Safety Office (SHSO) program managers to identify program characteristics and practices. A total of 105 LELs and 31 SHSO representatives completed the surveys. Nearly 75% of the LELs responded that they were directly accountable to their SHSOs. Over 75% of the LELs focused on impaired driving, occupant protection, distracted driving, and speed management. Specific LEL characteristics, such as superior communication and interpersonal skills, knowledge of State traffic safety laws and general police methods, connections with LEAs, and high energy and charisma were identified as important factors for a productive program.

A How-to Guide for Conducting a Statewide Roadside Survey of Alcohol and Other Drugs

This guide details the steps for a State to conduct its own statewide roadside survey of the prevalence of alcohol and other drug use among drivers, important components of addressing impaired driving. NHTSA has conducted several voluntary and anonymous National Roadside Surveys. NHTSA and also worked with the State of Washington State to conduct a statewide survey before and after legalization of the recreational use of cannabis in that State. If a State is interested in conducting its own statewide roadside survey, this guide draws on these past experiences to provide start-to-finish guidance on how to develop and implement a statewide survey of alcohol and other drug prevalence among drivers. The guide includes information on how to develop a study plan, budget, and conduct specimen collection, research questions that can be addressed, personnel and equipment needed, and issues that may arise.

Evaluating High Visibility Enforcement of Bicycle Passing Laws

This study selected Grand Rapids, Michigan, and Knoxville, Tennessee, to implement high-visibility enforcement (HVE) programs to increase compliance with laws requiring drivers to leave a minimum distance when passing a bicycles. In Grand Rapids, a local ordinance required leaving 5 feet, and in Knoxville the State law and local ordinance required a minimum 3 feet to pass. Police in both cities used the same ultrasonic measuring devices to determine if drivers passing decoy officers on a bicycles were too close. Each city developed its own publicity program to increase the visibility of the enforcement. HVE programs continued for approximately 4 months in each city. Results showed that the average passing distance in both cities during baseline was already well in excess of the prevailing legal requirement, but violations were still high. By the end of the HVE programs, statistically significant increases in average passing distance and significant decreases in violations were achieved in both cities.

Evaluation of Utah’s .05 BAC Per Se Law

On December 30, 2018, Utah became the first State to lower their legal driving limit from .08 to .05 g/dL. This research report is an evaluation of the impacts of this lower limit.

Detecting Change in Community Traffic Safety Attitudes

Historically, evaluations of community traffic safety programs have collected data using nonprobability intercept surveys rather than more rigorous probability surveys, or they used secondary data instead of primary data collection of any kind. However, it is not always feasible to use probability sampling when collecting data based on operational complexity, statistical complexity, cost, and timing constraints. This report may help build on basic statistics knowledge of community traffic safety program evaluators by highlighting sound practices for using nonprobability sampling methods and secondary data sources using opt-in online panel surveys with quota sampling and intercept surveys with quota sampling.