The emergence of connected and automated vehicles (CAVs) could have a significant impact on traffic efficiency and safety. The effects of CAVs in regular highway traffic are relatively well represented in scientific research. How these effects change in exceptional situations, such as work zones, and how the infrastructure can influence these effects is unknown however. Therefore, the main goals of this study are (1) to better understand the potential impacts of CAVs on traffic efficiency and traffic safety in highway work zones under different circumstances, and (2) to make a well formulated estimation of how current communication in work zones will need to be changed in the future. Two highway work zones were simulated in VISSIM. Three different types of CAVs (cautious, normal & all knowing) were implemented, each at 5 different penetration rate levels (0-100% with steps of 25%) in combination with conventional human operated vehicles to assess the traffic efficiency and safety effects. The traffic demand was kept constant at a theoretical F/C-ratio of 1. Based on first observations two communication strategies were added to the networks aimed at CAVs. These were (1) an early merge strategy and (2) an increased headway strategy. It was concluded that cautious CAVs have a negative effect on traffic efficiency and safety. The magnitude of these effects increased as the penetration rate increases. As CAVs became more aggressive, the traffic efficiency was increased. The traffic safety was deteriorated however, as a result of short time headways. The two communication strategies showed great potential to relieve the congestion in cautious CAV scenarios and to increase safety when entering the work zone.