The geography of sobriety checkpoints and alcohol‐impaired driving

Abstract

Background and Aims Sobriety checkpoints are an effective strategy to reduce alcohol‐impaired driving, motor vehicle crashes, injuries and fatalities. The aim of this study was to identify the geographic extent over which individual sobriety checkpoints affect alcohol‐impaired driving. Design, Setting, Participants Spatial ecological panel analysis using geolocated breath test data from the Queensland Police Service, Australia, for January 2012 to June 2018. Data were aggregated over 338 weeks within 528 Statistical Area level 2 (SA2) units (n = 178 464 SA2‐weeks) and 84 Statistical Area level 3 (SA3) units (n = 28 392 SA3‐weeks). SA2 units in Queensland contain a mean population of 8883.5 (SD = 55 018.3) and encompass 468.9 roadway kilometers (SD = 1490.0); SA3 units contain a mean population of 57 201.6 (SD = 29521.6) and encompass 2936.0 roadway kilometers (SD = 7025.0). Measurements Independent measures were the density of sobriety checkpoints conducted per 500 roadway kilometers within local and spatially adjacent space–time units. The dependent measure was the rate of tests that detected breath alcohol concentration (a proxy for blood alcohol concentration [BAC]) greater than the legal maximum value of 0.05% for fully licensed drivers in Queensland. Bayesian hierarchical spatial negative binomial models‐related sobriety checkpoints to the rate of breath tests with BAC ≥ 0.05% within and between space–time units. Findings One additional sobriety checkpoint conducted per 500 roadway kilometers was associated with 2.5% reduction in the rate of breath tests with BAC ≥ 0.05% within local SA2 units (incidence rate ratio [IRR] = 0.975; 95% credibility interval (CrI): 0.973–0.978), and with 5.5% reduction in the rate of breath tests with BAC ≥ 0.05% within local SA3 units (IRR = 0.945; 95%CrI: 0.937–0.953). Associations were attenuated towards null in spatially adjacent units and in temporally lagged units (e.g. SA3‐weeks; adjacent lagged 1 week: IRR = 0.969; 95%CrI: 0.937–1.003). Conclusions Individual sobriety checkpoints appear to be associated with reductions in nearby alcohol‐impaired driving. Relationships decay after approximately 1 week and beyond local areas containing approximately 60 000 residents and 3000 kilometers of roadway.

Anytime, anywhere: Understanding random breath testing deployments at the local level

“…That is, units of analysis must be practical and meaningful. To date, the smallest spatial unit used, without modification, in RBT research has been a Statistical Area 2 (SA2) unit (Morrison et al, 2021b). 1 This is likely due to the low number of traffic crash incidents.…”

“…It is not practicable to consider RBT counts over each minute of the day as there would be too little data for analysis. When temporal units are considered within the existing RBT, research days have previously been selected (see Morrison et al, 2019Morrison et al, , 2021b. This also represents a meaningful unit of analysis that can be readily incorporated in operational planning.…”

“…Internationally, research focusing on crash data, as the outcome variable, between 1980 and 2005 has found that introducing RBT programmes has been highly successful at reducing ARTC and traffic crashes generally (Erke et al, 2009). Recent studies have considered the impact of RBT programmes at state, city and community levels (Ferris et al, 2013;Morrison et al, 2019Morrison et al, , 2021b. Additionally, the implementation of RBT programmes differs across studies.…”

“…Some programmes targeted drink-driving offenders (specific deterrence), whilst other programmes aimed to increase general visibility (general deterrence) of police enforcement/checks (Ferris et al, 2013). Other strategies have included publicity campaigns, a focus on roadblocks or a focus on the total number of tests conducted (Erke et al, 2009;Morrison et al, 2019Morrison et al, , 2021b. Whilst the strategy has been successful overall, variations in effect sizes have been observed.…”

“…Despite the documented success of RBT operations, very little is known about when or where RBT is conducted within operational contexts (for exception, see Morrison et al, 2021b). Are RBTs truly conducted "Anytime, anywhere"?…”