Friends and colleagues mourned Richard H. Hefter Jr., a Prince William Planning Commission member who died last week, saying that his commitment to the environment and his community will be missed.

Hefter, 54, was killed in a car crash Thursday. He is survived by his wife, Philomena; and children, Sarah, 19, and Richard, 22, students at Virginia Tech.

"It's just devastating," said Supervisor John T. Stirrup Jr. (R-Gainesville). "He had just retired from the [Environmental Protection Agency] like two months ago. He was just really enjoying life, staying real busy and active."

Hefter served as the Gainesville representative on the Planning Commission from 1986 to 1989 and from 1992 to 1995, according to the county. Prince William Board of County Supervisors Chairman Sean T. Connaughton (R) appointed him to a third three-year term as an at-large member in March.

Over the years, Hefter and his wife joined many fights about development in western Prince William, from battles over a proposed mall near the Manassas National Battlefield Park to the plan to build a Walt Disney Co. theme park near Haymarket. He was a founder of the Northwest Prince William Civic Association.

"It wasn't that he was against development; he was for well-managed development that benefited the community at large,'' said Betty Rankin, a close family friend and fellow activist. "He was very pragmatic. He always went into each rezoning with an open mind. But he thought preservation had to be balanced with growth.''

Hefter's activism did not stop when he was off the Planning Commission. In recent years he had used his pen to fight projects and policies he opposed, and his letters frequently ran in The Washington Post.

"His was a voice of reason and rationality, and someone who understood the complexities of land use and the impact it has on the community," Connaughton said. "He had a great wit and sense of humor but never lost focus on what he thought was right for the community. He was a true community activist and leader, and he will be sorely missed."

Connaughton said the county is considering how to honor Hefter and his contribution. The chairman said he will appoint someone to fill Hefter's term, which expires at the end of 2007.

Hefter was killed around 2:30 p.m. Thursday. He was driving a 1994 Toyota Corolla when he pulled from Pageland Lane, where he lived, onto Route 29 near Gainesville and was struck by a southbound sport-utility vehicle.

He was hit on the driver's side and was pronounced dead at the scene, said Sgt. Kim Chinn, Prince William County police spokeswoman.

The other driver, a 63-year-old Manassas man with a Toyota RAV4, was not injured. Neither alcohol nor speed was a factor, and both drivers were wearing seatbelts, police said. The crash is under investigation; no criminal charges are pending, Chinn said.

"It was such a shock," said Martha Hedley, a Planning Commission member. "He's a careful person, not careless. I still can't believe it. While we know his family will miss him, the community will also miss him dearly.''

Arrangements had not been finalized by Friday evening, according to a family representative.