AUSTIN (AP) - State officials say cameras tucked into orange barrels videotaped the license plates of thousands of drivers on Interstate 35 as part of a transportation study.
Critics of last month's study questioned whether it invaded motorists' privacy.
But a Texas Department of Transportation spokeswoman says the study is vital to transportation planning and was not meant to be sneaky.
The state contracted Alliance Transportation Group to conduct the study.
The company mailed about 150,000 surveys to homes explaining that their license plate was randomly recorded. It asks questions such as the trip's destination and purpose, and the number of people living in the home.
Transportation Department spokeswoman Gaby Garcia says about 3,000 people have responded since the survey was mailed out three weeks ago.
She says the information won't be shared or sold and will be securely disposed of.
The department plans similar surveys next year in the Houston, Galveston, Beaumont and Port Arthur areas. Garcia says drivers will be notified ahead of time.