As configured today, the network doesn't need the bandwidth that WiMax provides, Alfaro said. But in the future, Caltrans plans to install video cameras for monitoring the situation on the highway. The WiMax network is ready to handle those data streams, he said.

Private, unlicensed networks make up only a small percentage of WiMax deployments, said IDC analyst Abner Germanow. Interference from Wi-Fi networks can be a problem. But in places where there aren't many Wi-Fi networks, such as on Highway 99, it's a realistic option, Germanow said. And for point-to-point wireless links, in general, WiMax is likely to displace proprietary systems and play a bigger role over time, he said. Standards mean many chipset and equipment vendors can make similar gear.

"The near-term reality of WiMax in point-to-point networks is that WiMax hasn't necessarily decreased the cost of that point-to-point equipment, but the longer-term promise is that as the volume of chipsets increases ... the prices on that gear will fall," Germanow said.

If the test deployment of Fog Pilot works as expected, Caltrans would like to set up sensors and signs in many other dangerous areas of the Central Valley. The system could also be used to warn drivers of other types of conditions and the accidents they may cause, Camarena said.