He served in the Army during World War II with the 84th Infantry Division Railsplitters. On returning home, he earned a degree in civil engineering from the University of Pennsylvania in 1949.
His first job was as a bridge draftsman for the Reading Railroad, and thus was born his fascination with bridges. Years later, the culmination of that interest was a Father's Day trip in which he walked the Brooklyn Bridge with his children and grandchildren. "He loved it," his daughter said.
Mr. Weir served as civil engineer for municipalities that included Upper Dublin, Upper Gwynedd, Upper Merion, and Ambler, all in Montgomery County. The firms he served were the North Wales Water Co. and the Ambler Borough Water Co.
He could hold in mind the details of the below-ground infrastructure that others would have to consult blueprints to discuss, his family said.
He loved his work, and carried it beyond his desk and drafting table, becoming a charter president of the Pennsylvania Society of Land Surveyors from 1969 to 1971. Later, he was named a fellow for his work with the organization.
He was awarded life membership in the American Society of Civil Engineers in 1986, as well as the American Water Works Association in 1971.
Mr. Weir was a member of Rotary International and served in leadership positions with the Ambler chapter. He was named a Rotary Paul Harris Fellow in 1983.
He seldom missed a meeting. Even on vacations he would find a local chapter and attend a meeting, his daughter said. His last Rotary project was moving a bridge once placed elsewhere to a site over the Wissahickon Creek on the property of the Wissahickon Valley Watershed in Ambler where it became the link needed to complete the Green Ribbon Trail.
In private life, Mr. Weir and his wife were long-standing members of Calvary Methodist Church in Ambler. They welcomed foreign students to their home through the International House, American Field Service, and Rotary.
Mr. Weir played the trombone, which he termed "a noble instrument," with the Ambler Symphony from 1952 to 1985, his daughter said.
He did woodworking and metal crafting in his home shop and turned out 26 mantel clocks for friends. His premier creation was a handmade grandfather clock that stands in his home. It strikes every 15 minutes.
Mr. Weir enjoyed sailing on the Chesapeake Bay; reading; taking photographs, which he developed in a home darkroom, and digging into natural history.
As part of a committee, he updated Penn's Woods: 1682-1982. The work inventories trees that were growing on the land grant William Penn claimed from the English crown. "He hunted down many of these antique trees, and photographed the ones he found to include in the book," his daughter said.
Besides his daughter, he is survived by a son, W. Thomson; another daughter, Sally Hayden; nine grandchildren; and seven great-grandchildren.
A visitation starting at 9:30 a.m. Monday, Jan. 6, in the auditorium at Gwynedd Estates, 301 Norristown Rd., Ambler, will be followed by a memorial service for Mr. and Mrs. Weir at 11 a.m. Inurnment is private.
Donations may be made to the Wissahickon Valley Watershed Association, 12 Morris Rd., Ambler, Pa. 19002.