He joined the Marine Corps in 1943 and was a sergeant major in the Fourth Marine Division invasion of Iwo Jima in 1945, one of the bloodiest battles of World War II. He was recalled to duty in the Korean War in 1951 and 1952.

His first marriage, to Jean Brown in the 1940s, ended in divorce. In 1952 he married Dorothy McArthur. She died in 1992. Besides their daughter, Dorothy, they had a son, Robert, who died at age 36. In 2003, he married Irene Allan Davis. In addition to her and his daughter, Mr. Blakeley is survived by three grandchildren and four great-grandchildren.

Mr. Blakeley studied landscape architecture at the University of California at Berkeley, graduating in 1954. After two years with the Veterans Administration, he joined the Army Corps of Engineers in 1956. To improve his speaking, he joined Toastmasters in 1958. He became its international president for 1976-77.

Given responsibility for the fallout shelter project, he decided that for durability, the signs would be made of metal, and that the colors and design would be simple and eye-catching, even in the dark chaos of a city under attack.

“It would have to be usable in downtown New York City, Manhattan, when all the lights are out and people are on the street and don’t know where to go,” Mr. Blakeley told Bill Geerhart, a blogger on Cold War topics, for an oral history that appeared on the website Conelrad Adjacent in 2006. The sign, he said, “had to be something that would get people’s attention and give them direction to the location.”

Image Robert W. Blakeley in 2007.

After experimenting with reflective paint in the basement of his Virginia home, he chose orange-yellow and black for the primary colors, and drew the sign as his children watched over his shoulder. The graphic design was suggested by Blair Inc., of Fairfax, Va., and was probably inspired by “Hornung’s Handbook of Designs and Devices,” published in 1932 and updated in 1946.