The design of a Cooperative Adaptive Cruise Control (CACC) platooning system is presented. The system allows for longitudinal control of Class 8 heavy duty trucks. A simple vehicle model was used to model the longitudinal dynamics, and a PID controller was formulated to control the vehicle to a set headway, or gap distance. An overview of the CACC system is provided, and experimental results are presented for both highway and forestry road driving. The results show that varying road grade has a significant impact on the controller performance. A simulation environment, implemented with TruckSim, is developed for studying the system and testing potential improvements to the control system. Future work and testing of this system is also discussed.