The problem of designing a decentralized Co- operative Adaptive Cruise Control (CACC) with quantifiable robustness margins with respect to network delays and in- termittent measurements is studied. A networked decentral- ized proportional-derivative controller is considered to achieve string stability for a platoon of vehicles. The closed-loop system is augmented with a timer triggering the arrival of new measurements. Sufficient conditions in the form of matrix inequalities are given to design the proposed controller with additional performance specifications. The effectiveness of the approach is shown in a numerical example.