Sensors are the eyes and ears of an automated vehicle. An automated vehicle has to detect other road users and should be able to interact with them in a safe way, hence it is important to understand what the vehicle's sensors should be capable of. We have investigated the different driving scenarios one can encounter in highway and rural environments, and sensing requirements have been derived for each of these scenarios. We have also listed the capabilities and drawbacks of different sensors, and have discussed possible solutions to enhance sensing performance and robustness. This thesis provides a good starting point for the selection of a sensor set for an automated vehicle.