CEDAR RAPIDS, Iowa (AP) — Iowa Department of Transportation officials are convinced that blue and white emergency lights on snow plows are effective at reducing crashes, and they’re going to seek a change in state law to permanently allow the lights.

KCRG-TV reports the department started a test project in 2015 to see if switching to blue and white lights would increase visibility and reduce crashes.

The agency found there were 29 crashes from October 2013 to April 2015 that involved vehicles rear-ending or side-swiping plows. After the blue and white lights were tested from October 2015 to April 2017, that number dropped to 10 crashes.

The agency is in its third year of testing and plans to ask lawmakers next session to change state law and make the new lights permanent every winter.