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Vision Zero analysis reveals drugs or alcohol involved in higher percentage of traffic fatalities than state data shows

Tuesday, October 24, 2023 by Nina Hernandez

An analysis by Austin’s Vision Zero initiative found that the presence of drugs or alcohol among Travis County traffic fatalities is higher than previously thought.

Vision Zero Analytics is a series of white papers by the Austin Transportation and Public Works Department as part of the overall effort to significantly reduce fatalities and serious injuries within the city.

The Vision Zero team released “Drugs & Alcohol Among Fatal Crash Victims: A Comparative Analysis of Toxicology Results and Crash Reports” in October. The report found that compared to Travis County medical records, Texas state crash reports for traffic fatalities “significantly” undercount the percentage of fatal crash victims who tested positive for drug use or who had a blood alcohol content of 0.08 or higher.

The analysis is based on a review of the Texas Department of Transportation Crash Records Information System database of crash reports, known as CR-3 reports, and toxicology reports from the Travis County Medical Examiner’s Office. From Jan. 1, 2018, to Dec. 31, 2022, there were 12 cyclist fatalities, 56 passenger fatalities, 38 motorcyclist fatalities, 175 pedestrian fatalities, 161 driver fatalities and six micromobility fatalities.

After reviewing the data, staff labeled each fatality as a binary “yes” or “no” for drugs or alcohol. The top three drugs detected were THC, amphetamines and cocaine. “Toxicology results in Austin varied significantly between agencies,” the report reads. “TCME noted (blood alcohol content) levels at or above .08 or positive results for drugs 47 percentage points higher than state CR-3 forms.”

While the Travis County Medical Examiner’s Office noted drugs or alcohol present in 77.3 percent of cases, the state results noted the presence of drugs or alcohol in just 29 percent of cases.

In terms of nondrivers and vulnerable users killed in collisions, Travis County Medical Examiner’s Office data reported BAC levels at or above 0.08 or drug use 33 percentage points to 67 percentage points higher than state crash reports, with the largest discrepancy occurring for fatal crashes involving cyclists.

According to the analysis, the Travis County Medical Examiner’s Office noted a BAC of at or above 0.08 or drug use in “most traffic fatalities across all modes, from 64% of passenger fatalities, on the low end of the range, to 100% of micromobility fatalities, on the high end.”

“This analysis does not imply that impairment was a causal factor in all of these crashes, but it does highlight the analytical limits of solely using crash reports to understand the top contributing factors and behaviors associated with severe crashes,” the report reads.

As the report notes, crash reports from law enforcement officers who respond to incidents have historically served as the primary source of information for understanding the facts and potential contributing factors of crashes. This can be an issue because the resulting crash reports rarely consider the influence of street design on collisions.

The report points to several other factors in the discrepancy. First, police officers may not update CR-3s with toxicology reports when the person killed is assumed to be at fault but did not kill or injure another person. Second, police rely on medical examiners to conduct toxicology screenings, while the Travis County Medical Examiner’s Office runs toxicology tests for all fatalities, unless the victim has been in the hospital for a long period or a “suitable biological sample” is not available around the crash time.

Third, the CR-3 forms do not have a space to note alcohol or drug use for passengers or people besides the driver or other primary person involved per unit, and therefore will undercount drug and alcohol use among victims. Fourth, there may be delays or inaccuracies based on available data and timing.

“These findings suggest that drug and alcohol use plays a far larger role in traffic fatalities than is suggested by crash reports, which have historically been the primary source of data for traffic safety efforts,” the report reads. “This analysis underscores the need to integrate alternative data sources, such as TCME data, into Vision Zero’s processes to provide more accurate information about the potential upstream causes of severe crashes and to better prioritize strategies and initiatives.”

Credit: City of Austin

Since the analysis, Vision Zero has started working with the Austin Police Department’s Vehicular Homicide Unit to update all fatal crash reports consistently moving forward “so that the crash data more accurately capture the extent to which drugs and alcohol are present in fatal crash victims,” the report reads. “Currently, this is a manual process and there is a desire to automate this in the future.”

This follows work in 2021 with the Austin-Travis County EMS and Austin Fire Department to understand their data systems and how to identify service calls that are related to motor vehicle crashes. The team has also established relationships with Austin Public Health and Dell Seton to acquire summary-level scooter injury data. Data and privacy standards with private health care facilities create barriers for the city in collecting that data.

Additionally, Vision Zero staffers are serving on an Impaired Driving Action Team, which was formed by Austin Public Health in October 2022 in an effort to bring together local and regional partners to implement evidence-based strategies using a public health framework to prevent impaired driving. That team – which focuses on enforcement, prosecution and diversion, data and improvement, education and awareness, and policy and prevention – continues to meet regularly.

Photo made available through a Creative Commons license.

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