Impacts of Subsidized Ridesharing on Drunk Driving, Alcohol Consumption, and Mobility

PROJECT SUMMARY Over 10,000 people die in alcohol-involved motor vehicle crashes per year in the US. Most available evidence identifies that access to ridesharing is associated with fewer alcohol-involved motor vehicle crashes. Providing access to subsidized rideshare trips could be a high impact intervention to reduce crash incidence and save lives. Some municipalities have begun implementing this strategy. Theoretically, access to subsidized ridesharing will replace trips by prospective impaired drivers by altering the financial and convenience costs of taking alternative forms of transit compared to driving while impaired. The strength of this association will differ according to an individuals’ income and local access to public transit. However, access to subsidized ridesharing may produce concomitant increases in alcohol consumption because greater mobility makes it cheaper and easier for consumers to obtain and consume alcohol. Few studies have tested these hypotheses, and there is no evidence from experimental studies. The broad objective of this two-arm single-blinded randomized controlled trial is to test the effects of access to subsidized ridesharing on drunk driving and alcohol consumption. We will recruit 160 individuals through digital social media advertisements from a stratified sample of 50 US cities (n = 8,000), including 25 cities with high access to public transit (as measured using the Transit Score) and 25 cities with low access to public transit. Participants will (i) reside in a selected city, (ii) be aged ≥ 21 years, (iii) have a drivers’ license and access to a motor vehicle, (iv) report consuming alcohol at a bar in the last 7 days, (v) own a smartphone, and (vi) speak English. We will randomize participants to receiving a $35 ridesharing voucher (the intervention group) or a $35 online shopping voucher (the control group). We will follow participants for one week pre-intervention and one week post-intervention using weekly surveys. A sub-sample of 2,000 participants will download a custom mobile application and will be tracked using GPS for the two-week study period. The specific aims are 1) to test whether access to subsidized ridesharing reduces individuals’ risks for drunk driving, 2) to test whether access to subsidized ridesharing affects individuals’ alcohol consumption, and 3) to test whether access to ridesharing affects individuals’ mobility, including access to retail alcohol outlets. We will assess moderation by individuals’ income and by the Transit Score for their city of residence. The results of this study will fill important gaps in scientific evidence regarding a disruptive technology with strong potential to be harnessed as a preventive intervention to reduce alcohol-involved motor vehicle crashes and improve public health. The work will inform the design of interventions that use subsidized ridesharing to reduce alcohol-involved motor vehicle crashes—including by identifying the individuals who will benefit most substantially, the locations where impacts will be greatest, and the unintended effects on alcohol consumption—and the mechanism by which the intervention achieves these outcomes (i.e. by altering individuals’ mobility and exposure to alcohol outlets).