As a consequence of insufficient situation awareness and inappropriate trust, operators of highly automated driving systems may be unable to safely perform takeovers following system failures. The communication of system uncertainties has been shown to alleviate these issues by supporting trust calibration. However, the existing approaches rely on information presented in the instrument cluster and therefore require users to regularly shift their attention between road, uncertainty display, and non-driving related tasks. As a result, these displays have the potential to increase workload and the likelihood of missed signals. A driving simulator study was conducted to compare a digital uncertainty display located in the instrument cluster with a peripheral awareness display consisting of a light strip and vibro-tactile seat feedback. The results indicate that the latter display affords users flexibility to direct more attention towards the road prior to critical situations and leads to lower workload scores while improving takeover performance.