Methods, systems, and apparatus, including computer programs encoded on computer storage media, for monitoring vehicles traversing a dedicated roadway that includes an at-grade crossing. In some implementations, a system includes a central server, a gate system, and sensors. The gate system provides access to an at-grade crossing for vehicles. The sensors are positioned in a fixed location relative to a roadway, the roadway including the at-grade crossing. Each sensor can detect vehicles on the roadway. For each vehicle, each sensor can generate sensor data and observational data from the generated sensor data. Each sensor can determine a likelihood that the detected vehicle will approach the at-grade crossing by comparing the likelihood to a threshold. In response, each sensor can transmit data to the gate system that causes the gate system to allow the autonomous vehicle access to the at-grade crossing prior to the autonomous vehicle reaching the gate system.