| The increase in traffic congestion has led researchers to focus on the use of automation in vehicles to make the current highway transportation system more efficient. Semi-automated vehicles are those equipped with automatic vehicle following control systems that provide automation only in the longitudinal direction and allow a vehicle to automatically follow another vehicle in the same lane as long as it is within the range of the forward looking ranging sensor. In this dissertation we designed such a control system using a high-level supervisory Petri net controller and a low-level Intelligent Cruise Control (ICC) controller. We have shown that the ICC system is live, bounded, asymptotically stable and all states in it are reachable. Furthermore, we have analyzed mixed semi-automated/manual traffic assuming single lane traffic flow with no passing. We have shown that the highway capacity increases with increasing semi-automated vehicles with frontal collision avoidance systems. At the microscopic level, we have shown that semi-automated vehicles improve traffic flow characteristics during both smooth and rapid acceleration maneuvers. We have demonstrated using simulations that the fuel consumption and pollution levels present in manual traffic can be reduced during rapid acceleration transients by 28.5% and 1.5%–60.6% respectively due to the presence of 10% semi-automated vehicles without any adverse effects on the total travel time and the traffic flow rate. Experiments with actual vehicles validated the theoretical and simulation results. At the macroscopic level, we have shown using flow-density curves that semi-automated vehicles increase traffic flow rate and traffic density. We have presented in a graphical way and demonstrated using simulations that the presence of semi-automated vehicles in mixed traffic propagates a shock wave faster than in manual traffic without affecting the total travel time. Lastly, we analyzed the effect of truck dynamics in traffic flow for future automatic controller designs for heavy-duty vehicles. We have shown and demonstrated that the presence of trucks decreases the speed of propagation of shock waves. |
