An amber traffic light presents a familiar dilemma: brake immediately or continue through the intersection? Making the wrong decision can lead to sudden braking, unnecessary acceleration or a dangerous encounter with another vehicle.

A 2026 study published in Analytic Methods in Accident Research suggests that connected-car technology could make these moments less stressful by helping drivers respond earlier and more smoothly.

When Every Second Counts

Researchers developed an advisory system using Cellular Vehicle-to-Everything (C-V2X) technology, which allows cars to communicate with roadside infrastructure and receive real-time traffic information.

The system provides guidance as traffic lights change from green to amber, helping motorists decide whether to stop or continue.

To investigate its effectiveness, the team recruited 62 licensed drivers for experiments using a sophisticated driving simulator combining Unity3D and VISSIM.

The virtual environment recreated approximately 4–5km of roads in Daejeon, South Korea. Participants drove under normal conditions and with the advisory system activated, producing 620 observations for analysis.

More Than A Simple Decision

Most previous studies have focused on whether drivers choose to stop or proceed when traffic lights change. However, the researchers wanted to understand what happens immediately afterwards.

A motorist might correctly decide to stop but brake so abruptly that a following vehicle has insufficient time to react. Similarly, deciding to continue could become dangerous if it involves excessive acceleration.

To capture these connected behaviours, the researchers developed a bivariate copula model. This statistical approach allowed them to examine drivers' decisions alongside their subsequent acceleration or braking while accounting for differences in driving experience and individual characteristics.

The results confirmed a significant relationship between the initial decision and the way drivers subsequently controlled their vehicles.

How Drivers Responded

The advisory system received high levels of driver trust and reduced participants' reported mental workload. Most drivers followed its recommendations, although compliance varied according to the type of guidance provided.

With the system activated, drivers were more inclined to proceed through intersections. Importantly, this tendency was not accompanied by more aggressive acceleration.

Participants who chose to stop also demonstrated smoother braking, with fewer instances of harsh deceleration. These findings suggest that timely information can influence more than the decision itself. It may also change how confidently and smoothly drivers carry out their chosen manoeuvre.

A New Approach To Road Safety

The research highlights the potential value of communication between vehicles and traffic infrastructure. Rather than relying exclusively on visual signals and last-second judgement, motorists could receive additional information when approaching an intersection.

For vehicle manufacturers and transport authorities, the findings provide evidence that advisory systems should be evaluated through both driver decisions and subsequent vehicle control.

However, the experiments took place in a simulated environment. The study demonstrated improvements in driving behaviour, not a reduction in actual road collisions. Further testing under everyday traffic conditions would be necessary before drawing conclusions about real-world safety benefits.

The broader lesson extends beyond traffic lights. As vehicles become increasingly connected, their value may lie not simply in providing more information but in delivering the right guidance at the moment drivers need it most.