A series of experiments was conducted on the Iowa Driving Simulator to examine driver reaction and performance in an intersection incursion crash scenario. To validate these simulator trials, a second study was run on a test track using a similar intersection incursion scenario to examine driver reaction and vehicle performance. Results showed that there was statistical equivalence between important driver reaction times with both studies.

Experiment: An experiment was conducted to assess the distraction potential of secondary tasks performed using in-vehicle systems (radio tuning, destination entry) and portable phones (10-digit dialing, selecting contacts, text messaging) while driving. One hundred participants, ages 25-64, completed a single session in which they drove a low-fidelity (PC-based) simulator while performing the secondary tasks. The phone tasks were performed with two smart phones, one with a touch screen interface (iPhone) and one with a hard button interface (Blackberry). The Dynamic Following and Detection (DFD) driving protocol, which combines car-following with target detection, in which drivers responded to simple visual targets presented in the simulated roadway display, was used. Each combination of primary (driving) and secondary task was performed during a single 3-minute drive. Driving performance metrics included: lane position variability, car-following delay, target-detection accuracy and targetdetection response time. Results: Text messaging was associated with the highest level of distraction potential. Ten-digit dialing was the second most distracting task; radio tuning had the lowest level. Although destination entry was no more demanding than radio tuning when task duration effects were eliminated with DFD metrics, it exposes drivers to more risk than radio tuning and phone tasks due to its considerably longer duration. Modest differences between phones were observed, including higher levels of driving performance degradation associated with the touch screen relative to the hard button phone for several measures. Additional analyses demonstrated that the way in which task duration is considered in the definition of metrics influenced the outcomes of statistical tests using the metrics. The results are discussed in the context of the development of guidelines for assessment of the distraction potential of tasks performed with in-vehicle information systems and portable devices. Additional analyses were conducted to compare the DFD and Alliance and decision criteria in a simulated compliance scenario. With the large sample size (N = 100), both protocols supported the conclusion that neither text messaging nor 10-digit dialing is suitable for combining with driving; however, when a smaller (N = 40) sample was used, the protocols led to different conclusions. Additional analyses found that for, using just the vehicle performance metrics (not the eye glance metrics), samples of 20 participants did not provide sufficient statistical power to differentiate among secondary tasks. Driver age had significant effects on both primary and secondary task performance; younger drivers completed more secondary task trials on a given drive, with relatively less primary task interference than older drivers. Tests conducted using samples with wide age ranges (25-64) required larger samples to compensate for reduced homogeneity relative to samples with narrow age ranges. Half of the participants were given specific monetary incentives...

No abstract

The report describes research to investigate the effects of wireless phone use on driving performance and behavior. The main objectives were to assess: 1) the distraction potential of wireless phone use while driving, and 2) the difference in distraction caused by the use of a Hands-Free wireless phone interface versus that associated with use of a Hand-Held interface. This research was conducted by NHTSA using the National Advanced Driving Simulator (NADS) in collaboration with NADS staff. Driving performance was examined in four events, including: (1) car-following, (2) lead-vehicle braking, (3) lead-vehicle cut in, and (4) merging. Phone conversation impaired performance most consistently during car following, resulting in an increase of approximately 0.3 to 0.4 seconds in drivers' delay in responding to lead-vehicle speed changes, relative to performance without phone conversation. Steering entropy (error) also increased during phone conversation in car-following events, reflecting an increase in high-frequency steering corrections. Increased steering reversal rates indicated increased workload during phone conversation. There was little evidence of performance impairment due to phone conversation for the other three events. Neither the lead-vehicle braking nor lead-vehicle cut-in events exhibited the predicted slowing in accelerator release and brake response times. The merge event also did not provide consistent evidence of degraded performance due to phone use generally, with the notable exception based on analysis of eye glance data, that while engaged in phone conversation, drivers devoted less visual attention to planning for an upcoming merge event. Older and younger drivers did not exhibit consistently degraded driving performance due to phone conversation than middle-aged drivers. There were modest differences among interface conditions. Specifically: (1) Hand-Held phone use interfered with steering and lane control more than the Voice Digit Dialing with Speaker Kit Hands-Free interface, and (2) the Voice Digit Dialing with Speaker Kit Hands-Free interface was associated with faster travel speeds than the Hand-Held interface. Differences between interface conditions were stronger for dialing and answering than for conversation. The Hand-Held interface was associated with fastest dialing times and fewest dialing errors while voice dialing was associated with fastest answering and hang-up times. No differences among interface conditions in phone conversation task performance were found. Post-drive questionnaire results showed that in most cases participants overestimated the ease of use afforded by Hands-Free phone interfaces. In general, participants considered the Hand-Held interface to be most difficult to use, followed by the Headset Hands-Free and Voice Digit Dialing with Speaker Kit Hands-Free interfaces, respectively.

No abstract