A key piece of one of the Homeland Security Department's biggest technology projects is facing doubts about whether it's feasible today given the current state of biometric technology.

The project involves using some type of standardized biometric technology to track the departure of foreign visitors, to ensure those who enter the country are the same as those leaving. Congress mandated that in the $10 billion U.S. Visitor and Immigrant Status Indicator Technology program passed after the Sept. 11 attacks.

Yet it will be at least five years before biometric technology is advanced enough for an infrastructure that can verify identities of people leaving the country via roadways without undue delays, says a report last week from the Government Accountability Office. Having motorists stop for a biometric check would mean major traffic jams or require huge expansion of border processing facilities. Homeland Security is evaluating technology to do the job. And it's already using biometrics, including fingerprint scanning, at 154 entry points to the country.

The question of biometric technology readiness shows the problem border officials face processing visitors at high-volume exit points. They're testing RFID readers as well, despite the mandate for biometrics. Better that than pushing a technology that's not yet up to the task.