As superintendent-engineer of the Marquette County Road Commission for 24 years (1951-1975), Shroeger upgraded the design and construction of the county road system and guided its development to one of the finest in the state. Serving also as Director of Public Works and manager of the Marquette County Airport, he led in providing the county with a public air facility second to none in the Upper Peninsula. He gained stature as both counselor and leader for Upper Peninsula county road commissions and as an architect of legislation important to county road systems throughout Michigan. Shroeger took on many assignments for the County Road Association of Michigan and was its president in 1959.