The Census Bureau will begin field tests next month for the 2010 census amid concerns that automated equipment being used for the first time could prove unreliable.

The use of automated data-collection devices is a major aspect of a redesigned census that officials say could save millions of dollars and provide more accurate results.

Harris is supplying mobile devices for the Field Data Collection Automation system. At $400 apiece, the devices have built-in Global Positioning System receivers so that census takers won’t need to carry paper maps and forms into the field when they try to locate people who didn’t mail in their census forms.

One aspect of the 2010 census -- a short form-only census -- has been tested successfully, said Mathew Scire, director of strategic issues at the Government Accountability Office. He said the short-form census will increase the response rate by about 1 percent, which will save the government about $75 million. The short form can be completed in less than 10 minutes.

Nevertheless, officials anticipate that the 2010 census will cost more than $11.3 billion to conduct, making it the most expensive in the country’s history.

Besides the new technical challenges, the bureau must recruit, hire and train 600,000 temporary employees and develop strategies for accurately counting people displaced in 2005 by hurricanes Katrina and Rita.