Abstract—In this paper, we propose an agent-based adaptive security-aware enhancement algorithm with congestion control mechanism for limited resources VANETs using intelligent transportation systems. The proposed security algorithm is to be installed at a central server that receives information about the vehicle resources from distributed intelligent road side units (RSUs) in a virtual segmented road via existing wireless cellular networks (4G). The security algorithm adaptively makes a decision about the best integrity security service level a source node can adopt while encrypting its data flows according to a resource estimation congestion control mechanism. The information about the security level decision will be transferred from the central server to the RSU via wireless cellular networks (4G). From the other side, the RSU transfers it to the source vehicle node via Wi-Fi direct technology. In finding the secure route to destination, we adopt our previously proposed secure cone-shaped request-zone LAR (SCSLAR). In order to notify the destination node with the security level that was adopted by the source, we override the 1st 3 bits of the 1st payload byte of the IEEE 802.11 wireless frame format to represent the associated integrity security level. Using three main network parameters: node density, vehicular speed, and number of malicious nodes, extensive simulation results based on QualNet simulator that is based on the GloMoSim used by Scalable Network Technologies (SNT) show that the proposed secure cone-shaped request zone LAR with resource estimation methodology (SCSLAR-RE) outperforms the SCSLAR regarding data delivery and in protecting the VANET from being congested by heavy traffic load through minimizing both the buffer consumption and the average packets delays at the destination side, while providing the best integrity security level to the data streams that make them robust against the alteration threat.