Driving to work, you notice the traffic beginning to slow. And because you have your cell phone on, the government senses the delay, too. A congestion alert is issued, automatically updating electronic road signs and Web sites and dispatching text messages to mobile phones and auto dashboards.

In what would be the largest project of its kind, the Missouri Department of Transportation is finalizing a contract to monitor thousands of cell phones, using their movements to map real-time traffic conditions statewide on all 5,500 miles of major roads.

It’s just one of a number of initiatives to more intelligently manage traffic flow through wireless data collection.

Officials say there’s no Big Brother agenda in the Missouri project – the data will remain anonymous, leaving no possibility to track specific people from their driveway to their destination.

Living where a “traffic jam” means you had to wait while the traffic light changed twice — I sort of vaguely remember things like this being a priority. But, for whom?

“Even though its anonymous, it’s still ominous,” said Daniel Solove, a privacy law professor at George Washington University and author of “The Digital Person.” “It troubles me, because it does show this movement toward using a technology to track people.”

Cell phone monitoring already is being used by transportation officials in Baltimore, though not yet to relay traffic conditions to the public. Similar projects are getting underway in Norfolk, Va., and a stretch of Interstate 75 between Atlanta and Macon, Ga.

But the Missouri project is by far the most aggressive – tracking wireless phones across the whole state, including in rural areas with lower traffic counts, and for the explicit purpose of relaying the information to other travelers.

Although most new cell phones come equipped with Global Positioning System capabilities that can pinpoint their exact locations, the tracking technology used for transportation agencies does not depend on that.

Instead, it takes the frequent signals that wireless phones send to towers and follows the movement of the phones from one tower to another. Then it overlays that data with highway maps to determine where the phones are and how fast they are moving. Lumping thousands of those signals together can indicate traffic flow.

The Electronic Privacy Information Center (EPIC) suggests that someone should notify cell phone owners that their phones are being monitored for traffic data.

Privacy experts also worry that the traffic monitoring could later evolve into other uses – perhaps to catch speeders or fugitives.

That’s because each cell phone has a unique serial number, in addition to its call number and a code that indicates its service provider. A cell phone company must always be able to track the location of its phones in order to know where to route a call.

“Perhaps to catch speeders or fugitives?” I don’t find that especially worrisome. Anything else come to mind?