01625674

Component

The use of mobile phones while driving remains a major human factor issue in the transport system. A significant safety concern is that driving while distracted by a mobile phone potentially modifies the driving speed leading to conflicts with other road users and consequently increases the risk of crash. However, the systematic lack of knowledge of the mechanisms involved in speed adaptation of distracted drivers prevents from explaining and modelling the extent of this phenomenon. The objective of this study was to investigate speed adaptation of distracted drivers under varying road infrastructure and traffic complexities. The CARRS-Q Advanced Driving Simulator was used to test participants on a simulated road with different traffic conditions, such as free flow traffic along straight roads, driving in urbanized areas, and driving in heavy traffic along sub-urban roads. Thirty-two licensed young drivers drove the simulator under three phone conditions: baseline (no phone conversation), hands-free and handheld phone conversations. To understand the complex relationship between distraction and road environment complexities, speed adaptation calculated as the deviation of selected speed from the posted speed limit was modelled using a decision tree. The identified groups of road environment complexities from the decision tree were then modelled with a Generalized Linear Mixed Model (GLMM) with repeated measures to develop inferences on speed adaptation behavior of distracted drivers. The GLMM also included driver characteristics and secondary task demands as predictors of speed adaptation. Results indicate that complex road environments like urbanization, car-following situations along suburban roads, and curved road alignment significantly influence speed adaptation behavior. Distracted drivers tend to select a lower speed while driving along curved road or during car-following situations, but the speed adaptation is negligible at the presence of large visual cutter, indicating the prioritization of driving task over the secondary task by drivers. Additionally, drivers who self-reported a high score in safe attitudes towards mobile phone usage, and who reported a prior involvement in a road traffic crashes are found to select lower driving speed in distracted condition than the baseline. The results aid in understanding how driving task demands influence speed adaptation of distracted drivers at various road traffic complexities.

This paper was sponsored by TRB committee AND10 Standing Committee on Vehicle User Characteristics.

01618707

17-04324

English

18p

2017

Transportation Research Board 96th Annual Meeting

Digital/other

Figures; References; Tables

Behavior; Crash causes; Distraction; Highway design; Highway factors in crashes; Mobile telephones; Speed; Traffic characteristics; Urban areas

Highways; Safety and Human Factors

Transportation Research Board Annual Meeting 2017 Paper #17-04324

TRIS, TRB, ATRI

Dec 8 2016 11:39AM