The first study of drivers texting inside their vehicles shows that the risk sharply exceeds previous estimates based on laboratory research — and far surpasses the dangers of other driving distractions.

The new study, which entailed outfitting the cabs of long-haul trucks with video cameras over 18 months, found that when the drivers texted, their collision risk was 23 times greater than when not texting.

The issue has drawn attention after several recent highly publicized crashes caused by texting drivers, including an episode in May involving a trolley car driver in Boston who crashed while texting his girlfriend.