John Lewis Weller, 75, a retired assistant director of the rail services planning office of the Interstate Commerce Commission, died Jan. 4 at the Carriage Hill Nursing Home in Bethesda. He had a heart ailment.

Mr. Weller, who lived in Rockville, was born in Rexford, Mont. He graduated from what is now Montana State University and earned a master's degree in transportation at Yale University. During World War II he served in the Navy.

Mr. Weller made his career in transportation. In the 1930s, he worked for the old New Haven Railroad and in 1969 he published a book called "The New Haven Railroad, Its Rise and Fall." After the war, he joined TWA as a vice president and remained with the airline until 1958.

In that year Mr. Weller became president of Seatrain Lines, a firm that shipped goods by rail and ship. He 1965 he joined a brokerage in New York and specialized in transportation issues. He was an investment adviser until moving to the Washington area in 1974 and joining the ICC. He retired in 1980.

Mr. Weller's marriage to Catherine Weller ended in divorce.

Survivors include two sons, John Craig Weller of Woodbridge, Va., and Dennis C. Weller of Wilton, Conn., and two brothers, Charles, of Whittier, Alaska, and Richard, of San Bernardino, Calif.