Donald F. Mela, 89, a retired division chief at the National Highway Traffic Safety Administration who spent decades as a civic activist in Alexandria and did free legal work for the economically disadvantaged, died Dec. 5 at his home in Alexandria. He had melanoma.

His daughter, Yonie Dow, confirmed the death.

Mr. Mela, who settled in Arlington in 1951, was a past president of the civic association in the Strawberry Hill neighborhood and served on the Alexandria Planning Commission from 1964 to 1977. He participated in the city’s efforts to minimize high-rise development on the waterfront and set guidelines for building.

Donald Ferdinand Mela was born in New York City and raised in Pelham, N.Y. During World War II, he served in the Army Signal Corps in the Pacific.

He was a 1947 mathematics graduate of the University of Michigan, where he also received a master’s degree in 1948. He was elected to the Phi Beta Kappa honor society.

Mr. Mela spent his early career at Defense Department think tanks doing statistical work. He joined the Transportation Department in 1968. He became chief of the mathematical analysis division at the NHTSA.

After his federal retirement in 1981, Mr. Mela enrolled at George Mason University’s law school. According to the publication Alexandria News, he liked to joke that he was the only graduate in the law school class in 1984 to pass the bar exam and collect his first Social Security check in the same year.

As a lawyer, he often worked for the Alexandria office of Legal Services of Northern Virginia. He was named a Living Legend of Alexandria in 2011 , an honor sponsored by an Alexandria nonprofit organization in conjunction with other local groups and companies. Mr. Mela also received a Virginia State Bar Association award for his pro bono legal work.

His memberships included the Alexandria League of Women Voters and Alexandria charitable organizations such as Alive, for which he helped deliver food. As an accordionist, he accompanied the Shooter’s Hill Ecumenical Carolers, which raised money at Christmastime for Children’s National Medical Center.

His wife, Doris Kaminsky Mela, whom he married in 1949, died in February. Their son Jonathan Mela died in 2005.

Survivors include two children, Yonie Dow of Alexandria and David Mela of Schiedam, the Netherlands; a sister; and seven grandchildren.

— Adam Bernstein