The national "511" highway information system is heavily used by drivers,especially during inclement weather, to plan and replan their trips. Few studies have explored the safety and usability of the 511 user interface, especially in the context of a mobile phone user who has the added workload of driving a vehicle. In this study, 36 drivers were divided into three groups (hand-held cell phone, hands-free cell phone, and control group) and drove a series of urban and rural scenarios in a high fidelity driving simulator. Drivers in the cell phone groups interacted with the Montana 511travel information system to obtain road information on a segment of highway. Performance on the primary driving task (e.g., lanekeeping and speed control) was not affected by use of the 511 traveler information system. Driving tasks that required urgent attention (e.g., responding to unexpected traffic conflicts) were degraded by using the 511 travel system regardless of the type of phone used. Drivers using either cell phone to interact with the 511 information system were found to have a higher number of collisions and less situation awareness than those not interacting with the 511 system. Drivers using a hand-held cell phone were also found to have a higher frequency of braking responses. The increased crash risk of the phone users in our study (3.0 - 3.8) was very comparable to that reported by earlier studies of the risk of cell phone conversations.
Abstract