On Wednesday, the Patrick administration proposed regulations to replace police officers on many state-financed road construction projects with less-expensive civilians, the kind of workers most states use. After a public hearing, the new rules could go into effect this fall.

The regulations are not as strong as some critics of the police details would like. They do not, for example, apply to locally financed road projects. But given the tenacity with which police unions have defended the details over the years  for example, swarming into the State House when Gov. William F. Weld proposed using civilians in 1992  budget experts say Mr. Patrick’s plan is welcome.

“It’s been a sore point for a long time  how come only Massachusetts has paid details to the extent that we do,” said Samuel R. Tyler, president of the Boston Municipal Research Bureau. “They might have a captain, a lieutenant, a sergeant and a couple of patrolmen working on one construction job. They’re even brazen enough that if you’re doing some work on the street and you don’t have a paid detail, they’ll come by and shut you down.”

Police officers say the regulations are a public safety mistake. “Any time you take police officers, who are highly trained, with the equipment that they bring, and put civilians out there who have minimal training, you are taking a risk in public safety,” said Richard R. Brown, president of the State Police Association, a union representing officers.

Transportation Secretary Bernard Cohen said there would be “significant” savings on the $25 million annual cost of police details. Mr. Cohen said civilians would be paid less  $34.85 an hour, for example, in the Boston area. Also, he said, they would be construction workers, so they could do road work when they were not needed to direct traffic.