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1C h a p t e r 1 The number of wireless (cell phone) subscribers has been growing exponentially. According to CTIA, The Wireless Asso- ciation, the number of wireless subscribers increased from 33.8 million in 1995 to approximately 315.9 million in 2011 (CTIA 2014). With CTIA reporting that subscribers in the United States used more than 2.295 trillion call minutes and sent more than 2.303 trillion text messages in 2011, it is clear that cell phone use has become a significant factor in day-to- day lives. This increase in cell phone use is of particular interest to scientists studying driver distraction. McCartt et al. (2006) conducted a review of approximately 125 studies related to cell phone use and driving. The study noted both in simulated and on-road driving studies that the results may be compromised by examining replicated or mock phone conversations as opposed to conversations that might occur naturally. Other research methods have involved obtaining cell phone billing records for a driver only after a crash has occurred. The cell phone records that corresponded to the time of the crash were then compared with records for the same driver from a comparable time period previous to the crash (Redelmeier and Tibshirani 1997). While this case- crossover approach provides data regarding crash risk associ- ated with cell phone use, it is not able to provide a clear picture of what was actually taking place in the vehicle at the time of the crash. Data from recent naturalistic driving studies that include video of the vehicle interior have also examined cell phone use in vehicles (Klauer et al. 2010; Olson et al. 2009). Such naturalistic data allowed researchers to examine what was happening inside the vehicle and in the surrounding environment just before, as well as during, crash-related events. These earlier efforts did not obtain the cell phone records of the driver, requiring researchers to search in a fairly cumbersome manner through the video data for instances, in which it was clear the participant was using a cell phone. A recent approach tied participantsâ cell phone records with naturalistic driving data (Fitch et al. 2013). The study recruited drivers who reported talking on a cell phone while driving at least once per day, and the results provided valuable information about drivers with a history of cell phone use while driving. The Second Strategic Highway Research Program (SHRP 2) Naturalistic Driving Study (NDS) provided the perfect oppor- tunity to create a database that would allow scientists to expand on previous research and further investigate cell phone use and the role it plays in driver distraction. The SHRP 2 NDS collected approximately 50 million miles of naturalistic driv- ing data from more than 3,100 different drivers over more than 3 years. The data collected included vehicle kinematic data, as well as video data of the exterior driving environment and video data of the driver. Adding driver cell phone records to this large database of participants across the driving age spectrum would provide researchers with a unique opportu- nity to explore research questions surrounding cell phone use and driving. It was decided that a substudy would be added to the SHRP 2 NDSâthe Cell Phone Records Study (CPRS). The purpose of the CPRS was to obtain as many cell phone records as possible from SHRP 2 NDS participants with the intention of adding these data to the SHRP 2 NDS database. The purpose of this report is to provide future researchers who wish to incorporate CPRS data into their analyses with essential information about these data and how they were collected. The report describes the methods used to recruit and enroll participants in the CPRS. The details surrounding the collaboration with the cell phone carriers and the pro- cesses of obtaining data from the wireless carriers and directly from the participants are also explained. Summary informa- tion about the data collected and the limitations of the data are discussed as well. Background
