This project developed and demonstrated a variety of smart-transport technologies, policies, and practices for highways and freeways using connected autonomous vehicles (CAVs), smartphones, roadside equipment, and related technologies.

Autonomous intersection management (AIM) was discussed for networks with connected automated vehicles (CAVs) and human-driven vehicles (HVs). The strategy included a reservation-based protocol in which CAVs could request to reserve trajectories crossing an intersection using a “first come, first served” (FCFS) policy, and an automated intersection manager would approve the reservation requests only if it did not conflict with any previously approved reservation or an HV.

The AIM protocol did not rely on communication capabilities between vehicles (V2V) but only between vehicles and the intersection manager (V2I). The protocol was robust to communication failures: if a message was lost, either by the intersection manager or by the CAV, the system’s efficiency may have been reduced, but safety was not compromised. Safety was guaranteed also when considering a mixed scenario where both HVs and CAVs were present.

SYSTEM COST

With respect AIM, Hybrid-AIM, or D-tolling, the most critical piece of hardware necessary is a roadside unit (RSU) capable of supporting V2I communication. Cost data from one source suggests that a RSU providing both cellular and DSRC communication technologies can be deployed for approximately $6,000 per intersection. In addition to providing sufficient communication capabilities for implementing AIM or H-AIM, this solution may also provide data on travel times over a road segment.

Alternatively, a traditional signal controller that provides network communications may be suitable to support H-AIM. The Siemens M60 advanced traffic controller (ATC) which is capable of running Linux and features a minimum of two network interfaces was estimated to cost $5,000, which in most use cases is sufficient to control a single intersection. This model can be found commonly in the field where newer traffic controllers have been installed.