George Donald Hanrahan, 53, a senior economist in the Office of the Assistant Secretary of Commerce for Economic Affairs, was killed Saturday in a traffic accident in Wauwatosa, Wis., while on vacation.

A spokesman for the Wauwatosa police department said Dr. Hanrahan was driving alone when another vehicle jumped a traffic light and struck his car broadside. The spokesman said Dr. Hanrahan was pronounced deak at a local hospital and that charges were pending against the dirver of the second car.

Dr. Hanrahan, who lived in Fairfax, joined the Commerce Department in 1975. He specialized in monetary, investment and inventory analyses and had contributed to a major study of the economy of Puerto Rico.

He was born in Milwaukee. He served in the Army in the early 1950s and earned a bachelor's degree from Marguette University in 1954. He earned master's and doctoral degrees at the University of Minnesota and was an instructor there. He was as associate professor of economics at St. Louis University in St. Louis, Mo., from 1960 to 1971 and at the South Bend campus of Indiana University from 1971 to 1975. He then went to work for the federal government here.

His marriage to the fomrer Dorothy Hughes ended in divorce.

Survivors include three children, Tim, Galen and michael, all of Fairfax, a brother, Kenneth, and a sister, Elanor Bittner, both of Milwaukee.