Effects of Work Zone Infrastructure on Transitioning From Automated to Manual Driving for Work Zones With Lane Reductions

This study explored the impact of work zone infrastructure on driver response when transitioning vehicle control from SAE International (SAE) Level 2 automation to the human driver (SAE 2014). Study participants drove a test vehicle at about 50 mph on a four-lane, undivided, closed-track highway. The participants drove two passes through a work zone with a lane reduction. The participants received simulated cooperative driving automation (CDA) messages representing four types of work zones: a standard work zone, which uses work zone signing specified in the Manual on Uniform Traffic Control Devices for Streets and Highways; a machine-readable work zone, which uses signs to transmit work zone-specific information that can be used during a takeover request; a work zone equipped with a CDA device, which uses machine-to-machine (M2M) communication to relay basic information about the work zone, and a smart cooperative automated driving system work zone, which also uses M2M communication to convey work zone-specific information (FHWA 2012). Three types of CDA messages were provided to participants: basic, detailed, and no message (control condition). These messages were based on the amount of detail provided (basic versus detailed) and how far in advance of the work zone they were provided (short notification lead time versus long notification lead time). The results suggest that detailed CDA messages tend to have a greater impact (on some drivers and not others) when disengaging advanced driver assistance system (ADAS) features, merging into the open lane, and paying attention to the in-vehicle display. This study’s findings on the use of CDA messages to increase the safety of Level 2 ADAS vehicles supported transportation systems management and operations work zone safety strategies (SAE 2014). The study also showed the benefits of using CDA messages in Level 2 ADAS vehicles with partial automation when approaching a work zone (SAE 2014).