ST. PAUL, Minn. — All Minnesota school buses built after Jan. 1 of next year will have to be equipped with crossing arms.

State legislation signed into law this spring mandates the devices, which extend automatically from the right side of the front bumper to deter kids from crossing too close to the bus.

The mandate will only apply to new school buses — existing buses that don't have crossing arms won't have to be retrofitted.

It was not immediately clear how many of Minnesota's current school buses are equipped with crossing arms, but state pupil transportation director Lt. Brian Reu told SBF that they are more prevalent in contractor fleets. In many cases, contractors' agreements with school districts require crossing arms on their buses.

State Rep. Larry Howes introduced the legislation last year, with support from the Minnesota School Bus Operators Association (MSBOA).

Howes noted that many buses in the Twin Cities metropolitan area already have crossing arms, but it is rare in northern Minnesota. “That’s why I want to do it statewide,” he said.

The bill was spurred at least in part by a fatal accident in Howes' district. In March 2010 in Pine River, Minn., 6-year-old Evan Lindquist was struck and killed by his school bus as he was crossing in front.

Evan's parents were in attendance in April of this year when Gov. Mark Dayton held a ceremonial signing of the crossing arm bill. The mother and father wore T-shirts with their son's picture on them.

MSBOA officials have said that the approximately $300 to $350 to add a crossing arm to a new school bus is a small price to pay for the safety enhancement it provides.

But others have raised concerns about the possibility of a crossing arm malfunctioning — particularly in icy winter conditions — and putting the bus out of service.

Reu said that his office is reworking its school bus inspection rules to account for the new crossing arm requirement.

"We're still trying to figure out how we handle it if the crossing arm goes down mid-route and what happens on the pre-trip," Reu said.

For example, should the bus be allowed to go out on a run if the crossing arm isn't working?

"I don't think so," Reu said. "We made a big deal about getting this [legislation] passed, so it should be working. It's an added safety piece."

However, he noted that the addition of a crossing arm doesn't lessen the school bus driver's role.

"Ultimately, it still comes down to the driver," Reu said. "The driver is still responsible for making sure the kids are far enough away from the bus."