Austin firetrucks now must drive the speed limit and come to a complete stop at intersections while responding to calls, according to a new city policy that has upset the firefighters union.

Fire Chief Rhoda Mae Kerr said the policy is intended to improve safety for firefighters and motorists. But Steven Truesdell, president of the Austin Firefighters Association, said firefighters’ discretion is being unnecessarily curtailed, possibly increasing response times. “It appears to be a way for the fire chief to shift more responsibility on the individual firefighter,” Truesdell said.

Under previous policies, firefighters could drive up to 10 mph over the posted speed limit. At intersections, they were not required to stop but were instructed to make sure drivers were aware that they needed to get through.

As a practical matter, firefighters were already stopping at stoplights and intersections before proceeding, fire officials said. And because of traffic congestion, they said, fire engines rarely are able to drive much over the speed limit.

Kerr and other Fire Department officials said the new policy, which took effect Aug. 11, will not affect response times.

“It is all about making sure that everyone goes home,” Kerr said. “It helps. keep our people safer not only the firefighters, but the community as well.”

Department spokeswoman Michelle DeCrane said the new policy is based largely on a 2003 report in EMS Responder magazine on response data from several studies, including ones in Syracuse, N.Y., Minneapolis, and the state of North Carolina.

The report concluded that EMS vehicles traveling at the speed limit and stopping at intersections basically having to obey the rules the Fire Department just put in place drove more safely and experienced significant delays only in isolated instances.

Truesdell said any delays could be significant. He said firetruck drivers should not be required to stop at intersections if traffic is light and the crew determines there is no chance of a collision.