The state Transportation Department is getting ready to spend $1.5 million replacing metric signs along Interstate 10 with mileage signs, to the chagrin of some businesses along the highway. The state plans to use federal stimulus money to replace the signs, which it previously planned to replace as the signs wore out. The signs marking kilometers instead of miles were first installed in the early 1980s when I-19 and a handful of other roads were signed in metric as the country considered a full conversion. That conversion hasn’t happened.