Real‐World Personal Conversations Using a Hands‐Free Embedded Wireless Device While Driving: Effect on Airbag‐Deployment Crash Rates

Abstract

A wireless device embedded in the vehicle allowed the user to engage in a personal hands-free conversation (HFC), and automatically placed an emergency notification call to an OnStar call center if the vehicle was involved in a crash in which its airbag deployed. A database stored the exact counts, start timestamps, and billed durations of all HFC and airbag notification calls. In 30 months of naturalistic driving, there were 91 million HFC calls from an average of 323,994 drivers per month who made calls. There were 14 airbag deployments in 276 million driver-minutes of HFC conversation for an exposed incidence rate of 5.08 airbag crashes per 100 million driver-minutes. There were 2,023 airbag deployments in an estimated 24.7 billion driver-minutes of no HFC conversation for a not-exposed incidence rate of 8.18 airbag crashes per 100 million driver-minutes. The crash incidence rate ratio (IRR) is the ratio of these two rates or 0.62 (95% C.I. 0.37 to 1.05). Sensitivity analyses controlled for the impact on the crash IRR of estimated time spent driving per day and calls by passengers. Counting all crashes as much as 20 minutes later than a call as related to that call gave similar results. We conclude that for personal conversations using a hands-free embedded device the risk of an airbag crash is somewhere in a range from a moderately lower risk to a risk near that of driving without a recent personal conversation. These results are not consistent with the large increase in crash risk reported in epidemiological studies using the case-crossover method.

Naturalistic Studies of Driver Distraction: Effects of Analysis Methods on Odds Ratios and Population Attributable Risk

“…Differences between the VTTI 100-Car OR estimate for Talk 1 and those from independent real-world studies 2,3 led to the question of whether methodological issues could underlie the differences. A Standard Method of epidemiological analysis using the 100-Car databases was compared to published results from the VTTI Method.…”

“…1,11 The Standard Method was free of this bias and error, and estimated OR and P e % effect sizes for Talk which were consistent with those in independent studies. 2,3,13,14 Root Cause of Positive OR Bias. The VTTI Method 1,11 caused high OR estimates because it counted only at-fault unexposed cases (which enter the OR denominator), but counted all cases, regardless of fault, for the exposed cases (which enter the OR numerator).…”

“…1), with a CI below 1, in another NDS, using heavy vehicles in fleets with no cell phone policy. (2, cohort study of 3 million vehicles equipped with the OnStar device, 3 the rate ratio for airbagdeployment crashes during hands-free personal calls was 0.62 ( Fig. 1), with a CI mostly below 1.…”

Validation of the Static Load Test for Event Detection During Hands-Free Conversation

“…Young and Schreiner (2009) hypothesize that the low crash risk in their real-world study "can be explained if drivers making personal wireless calls using the OnStar embedded hands-free calling device are taking responsibility to: (1) make prudent and safe choices about engaging in calls during adverse road, environmental, or traffic conditions, (2) reduce or postpone elective driving maneuvers or secondary tasks that might increase crash risk when in a call, and (3) adapt conversations while in a call to accommodate road and traffic conditions." Drivers might also be compensating for the predicted small RT increases from hands-free conversations using this device by simply taking extra care to keep their eyes on the road, hands-on-the-wheel, and mindon-the-drive.…”

“…A recent real-world epidemiological study (Young and Schreiner, 2009) compared personal conversation crash rates to no-conversation crash rates using a hands-free wireless device "embedded" or built into the vehicle. This study found no increase in airbag-deployment crash rates for personal conversations using the device, compared to driving without conversing on the device, consistent with the low crash risk found by Young (2001) for calls to an OnStar advisor.…”