On the potential of traffic light information availability for reducing fuel consumption and NOx emissions of a diesel light-duty vehicle

The paper addresses the impact of traffic light information availability in terms of fuel consumption and emissions by means of comparing three different scenarios that a driver of a diesel light-duty vehicle may face when trying to cover a particular route of 1 km with two traffic lights in between. The first scenario is that the driver does not know in advance the state of the traffic lights. The second scenario assumes that the driver knows the state of the traffic lights but has no modelling nor computation capabilities to solve the associated optimal control problem. In the third scenario, the driver knows in advance the state of the traffic lights and is also able to solve the corresponding optimal control problem that leads to fuel consumption or NOx emission minimisation. In this study, the vehicle-speed trajectories associated with the previously described three scenarios have been computed and then tested in a Euro 5 Diesel vehicle installed in a chassis dynamometer. The obtained results show that traffic light information is essential for fuel minimisation in urban conditions, promoting reductions of 7.5–12% and 13–32% for fuel consumption and NOx emissions in the studied case. In addition, differences in the engine-operating conditions for high efficiency and low NOx emissions may lead to extremely high fuel consumption when NOx minimisation is foreseen or viceversa.