The use of connected autonomous vehicles (CAVs) can help reduce the gaps between vehicles. However, smaller gaps may cause challenges for on-ramp vehicles to merge on the freeway. This study introduces several strategies that allow on-ramp vehicles to merge safely and efficiently with the mainline by providing adequate merging gaps or resolving merging conflicts in a mixed traffic environment. Eight methods are proposed to facilitate merging. These strategies are simulated in a mixed traffic environment with different traffic characteristics, including different proportions of CAVs. The results indicate that the operational performance is affected by the CAV penetration rate and traffic management strategy. For a relatively low freeway traffic volume or 100% CAV penetration rate, traffic operations under the do-nothing option perform almost as well as the best traffic management strategy. However, at lower CAV penetration rates and high freeway traffic volumes, the proposed strategies are more viable than the do-nothing option.