Influence of Smart Cruise Control Functions on Surrounding Traffic

Sammanfattning

Smart Cruise Control (SCC) strategies for heavy-duty vehicles (HDVs) are tuned mainly for fuel economy on long motorway routes. These strategies allow the truck to deviate from its fixed set-speed in order to save energy on the uphill and downhill sections of the route. Such deviations can also influence the vehicles traveling around the truck. These effects on the surrounding traffic are rarely considered when SCC strategies are evaluated, as the main focus is usually on the fuel benefits for the truck itself. This thesis evaluates how different SCC strategies in HDVs affect local traffic around an SCC-equipped truck on a motorway. The evaluation is carried out using microscopic traffic simulation in Vissim for a 117 km segment of the E4 motorway corridor in Sweden. Five SCC strategies are compared under four traffic volumes and two HDV penetration levels. The effect on the surrounding traffic is described using three main metrics. These metrics cover HDV-specific queueing behind the SCC truck, cumulative delay for vehicles traveling behind the SCC truck, and stalled HDV overtaking in the left lane. The results show that no single SCC strategy removes the local traffic disturbance around the SCC truck. Instead, the strategies change how the disturbance is distributed across vehicle groups and lanes. The strategy closest to fixed-speed cruise control produces the highest HDV-specific queueing, but it causes lower passenger-car delay and less left lane interference than the stronger speed-reduction strategies. The strategies with larger speed reductions reduce HDV queueing but tend to shift more disturbance to passenger cars and to stalled HDV overtaking in the left lane. The size of the strategy gap depends on traffic volume, and it changes only slightly when the HDV share increases from 10% to 15%. The main contribution of this thesis is a structured framework for evaluating SCC strategies through their effect on surrounding traffic. The three main metrics make it possible to compare strategies in a consistent and reproducible way. The findings show that the preferred SCC strategy depends on which type of disturbance is considered most important, rather than on one generally best strategy.