Frequency and impact of hands-free telephoning while driving - Results from naturalistic driving data

The frequency and impact of hands-free telephoning while driving was analyzed based on naturalistic driving data from 106 drivers. The results from naturalistic driving data were compared with the results from experimental approaches. The implication of the overall results and the differences across drivers are discussed. Continuous information on the usage of the hands-free phone equipment was available which made it possible to include the entire database (∼1 000 000 km) in a completely automatized analysis. Results show that drivers talked on a hands-free phone about 11% of driving time. There were large differences across drivers in the frequency and usage of a hands-free phone. While telephoning, an adaptation of driving behavior could be found. Drivers slowed down and increased their distance to the lead vehicle. Furthermore, during telephoning, an overall reduction of potentially critical driving situations was found. Overall, the results indicate that compensation for telephoning was carried out with a long-term change of driving behavior, rather than with a short term adaption to the situation.