The Harris County Toll Road Authority has lost more than $3 million in the three years it has permitted its EZ Tag holders to use their passes to pay for airport parking, a Chronicle analysis has found.

The losses prompted Commissioners Court to shut down the program three weeks ago at the authority's recommendation.

The court's action does not take effect for six months from its Jan. 12 vote. At its current monthly loss rate, the program will lose nearly $500,000 more as it sunsets.

By canceling the program more than two years early, the authority is giving up on about $2 million it expected to collect to pay off the equipment for reading the EZ Tags of vehicles exiting the parking garages at Bush and Hobby airports.

Although it had expected to recoup the entire $4.1 million cost of the system through gate receipts, authority officials do not view giving up on $2 million in future collections as a total loss. The system will be redeployed elsewhere on its toll road network, saving on replacement costs for worn-out equipment, officials said.

"It is foolish to spend a dollar to collect 50 cents," Peter Key, deputy director of the authority, said in a statement. "Ending the airport EZ Tag Program is the right thing to do. It is not easy to acknowledge that a program does not meet revenue expectations, but it would be irresponsible for this agency to continue to expend public funds on a program where revenue consistently does not meet expenditures."