Framing Effects in Personalized In-Vehicle Freeway Traffic Messaging: A HUD-Based Approach

Effective communication of traffic information is critical for freeway safety. Yet, Traditional road signs and variable message displays often fail to capture drivers’ attention, as evidenced by persistent speeding-related crashes on highways. Advances in connected-vehicle technology and head-up displays (HUDs) now enable real-time, personalized in-vehicle warnings, offering new opportunities to enhance speed compliance. At the same time, these systems introduce an important design challenge: the effectiveness of warnings may depend on how messages are framed (e.g., emphasizing benefits versus risks), particularly under time pressure and varying driver characteristics. Despite its theoretical importance, the impact of message framing in real-time, HUD-based speed warning contexts remains insufficiently understood. This study proposes and evaluates a Freeway-Centered Dynamic Speed Warning System (F-DSWS) that delivers real-time speed warnings via vehicle-to-infrastructure communication and HUD interfaces. Two message-framing strategies were examined: gain-framed messages emphasizing positive and socially relevant outcomes, and loss-framed messages highlighting safety risks. A driving simulator experiment was conducted with 39 licensed drivers aged 19–78 years across multiple freeway scenarios. Results indicate that HUD-based warnings significantly outperformed traditional roadside signs in reducing speeding, lane-deviation extremes, and harsh braking. Moreover, gain-framed messages consistently produced greater improvements in driving performance than loss-framed messages across all evaluated metrics. These findings suggest that the proposed F-DSWS provides measurable safety benefits and demonstrate that framing choice is a critical design factor in personalized in-vehicle freeway traffic messaging. These results offer evidence-based guidance on framing selection within HUD-based in-vehicle freeway warnings, and support future field deployment of the proposed F-DSWS to improve freeway safety.