From red lights to ‘greener’ driving? The potential of mobile traffic signal countdown information for urban emission mitigation

Summary Urban transport remains an important source of energy consumption and air pollutant emissions, particularly under the transient driving conditions associated with signalized intersections. This Comment examines the integration of real-time traffic signal countdown information into mobile navigation platforms as a potential low-cost digital behavioural intervention for improving urban transport efficiency. Drawing on published field observations and simulation studies, we show that previous research has associated access to signal timing information with smoother driving trajectories, reduced unnecessary idling and acceleration and lower fuel consumption and traffic-related emissions under specific traffic and control conditions. Building on this evidence, our aim is to place countdown-informed driving within a broader environmental management framework and to examine how existing digital infrastructure could be used to support behaviour-based emission mitigation without requiring major physical infrastructure changes. We further identify driver response, safety, signal data reliability, accessibility and governance as critical factors determining whether these potential benefits can be realized in practice. More broadly, we propose traffic signal countdown information as an illustrative case of how digitally enabled behavioural adaptation may complement technological and infrastructural strategies for more sustainable urban mobility.