Iowa Department of Transportation (IDOT) is changing its replacement schedule after a study found that the fleet could save $2 to $5 million annually by replacing its snow plows earlier. IDOT enlisted the help from two professors at Iowa State University to determine the most efficient lifecycle for its fleet.

Keith Schiebe and Sree Nilakanta, associate professors of information systems, analyzed 10 years of maintenance records for about 900 single- and tandem-axle IDOT snow plows to identify the optimal time for replacement. The professors conducted a simulation study using the maintenance records, purchase price, and resale estimates.

The study concluded that the optimal lifecycle was six to seven years — compared to IDOT's current 15-year replacement window. With shorter lifecycles, the professors estimate IDOT to save $2 to $5 million annually in maintenance.

“This research bore out what we suspected to be true. In fact, it’s the most solid evidence that we have to show that we really need to reduce the amount of time that we keep our snow plow trucks,” David May, IDOT fleet manager, said in a statement.

IDOT has decided to gradually follow the suggestions from this study, cutting down the replacement window to 12 years, The Gazette reported.