It will cost $1.5 million to change Interstate 19 into just another U.S. highway with distances posted in miles. The Arizona Department of Transportation will soon replace 400 metric and exit signs on the highway between Tucson and Nogales using funds from the American Recovery and Reinvestment Act (ARRA).

The signs, which dot the 63 miles (or 100 kilometers) of Interstate 19, were erected in the 1980s when the United States was weighing a conversion to the metric system, said ADOT spokeswoman Linda Ritter.

Replacing the signs is a priority for two reasons, Ritter said.

“The signs don’t meet the retro-reflectivity standards,” Ritter said. This refers to how bright the signs are at night using only the driver’s headlights. “It’s been deemed a safety priority.”

The other reason is that the aging signs have outlived their useful life, Ritter said. Two sections of the Arizona Revised Code — ARS 28-363c and ARS 28-3046 — prevent ADOT from building or designing anything metric unless the entire country is converting to that system.

Some residents of Santa Cruz and Pima counties think the project is a waste of the stimulus money. Karen Rogers of Rio Rico called the highway sign project “misdirected” and much less important than a bridge at the Palo Parado crossing in her letter to the editor published May 1.

“Over the past several years, residents of Rio Rico have been forced to beg and plead with county, state, and federal officials to fund a much-needed bridge over the Santa Cruz River,” Rogers wrote. “This project is one that affects the economics, welfare, safety and health of thousands of residents and businesses.”

The Green Valley Community Coordinating Council wrote to Gov. Jan Brewer on March 27 and appealed to her to keep the metric signs, according to a report in the Green Valley News. Businesses would have to spend money redoing their promotional materials, it said.

At the end of April, the state engineer sent a letter and explained that the sign replacement project had been in the works for some time, said GVCCC President Stan Riddle. “Unfortunately, we were never informed.”

Riddle would prefer ADOT to attach smaller signs that show the distance in miles, he said.

ADOT will put the job out to bid in June and work should begin by August, Ritter said. The project will create about 30 jobs.

Exit numbers will also change, but signs will indicate both the old and new numbers for two years, Ritter said. This will give businesses that advertise their locations by the current exit numbers time to make changes.