MASON CITY – A sweeping reconstruction of one of Mason City’s busiest commercial corridors would replace six signalized intersections with roundabouts, rebuild the four-lane highway and add new pedestrian, bicycle and drainage improvements.
The Mason City City Council received an updated preliminary design for the Highway 122 West project during a work session held at 6 p.m. Tuesday, August 4, 2026, at the Mason City Public Library.
The study area extends from Lark Avenue to just east of Winnebago Way, although the primary reconstruction corridor discussed stretches approximately two miles from Willow Creek to the pavement transition east of Winnebago Way and Cerro Gordo Way.
The proposed roundabouts would replace traffic signals at:
Indianhead Drive
Eisenhower Avenue
Roosevelt Avenue
Taft Avenue
Grover Avenue
Winnebago Way
The project would also create partial-access intersections between the roundabouts, reconstruct the four-lane divided highway with curbs, gutters and a raised median, add a shared-use trail and sidewalks, replace storm sewer pipes and intakes and introduce landscaping or other aesthetic features.
The goal is to improve safety and traffic capacity, replace aging pavement and underground infrastructure, accommodate pedestrians and bicyclists and preserve access to the many restaurants, stores, hotels and other businesses lining the highway.
Former Mayor Bill Schickel previously described the busy west-side corridor as Mason City’s “million-dollar highway” when outlining plans to reconstruct and beautify major gateways into the city.
Design engineer Chase Holien of WHKS and Company told council members that roundabouts reduce the number of places where vehicles can cross, merge or diverge. A conventional four-leg signalized intersection can have 42 vehicle conflict points, compared with 24 in a comparable roundabout.
Statistics presented during the meeting indicated that intersections converted from traffic signals or stop signs to roundabouts have experienced a 72% to 80% reduction in injury crashes and a 35% to 47% reduction in crashes overall. Roundabouts can also reduce delays and the number of times vehicles must come to a complete stop.
Pedestrian crossings would include refuge areas approximately 12 to 16 feet wide. Those islands would allow walkers and bicyclists to cross one direction of traffic at a time instead of traversing the entire highway in a single movement.
Holien said the roundabouts would be large enough to accommodate ambulances and 67-foot semitrailers. A paved truck apron around the center island would give large vehicles additional room to maneuver while encouraging passenger vehicles to remain in their designated lanes.
Construction is expected to be divided into four projects spread across five years:
2028 – West of Taft Avenue to west of Briarstone Drive
2029 – East of Eisenhower Avenue to west of Taft Avenue
2030 and 2031 – Willow Creek to east of Eisenhower Avenue
2032 – West of Briarstone Drive to east of Winnebago Way
Although construction would be divided into phases, preliminary engineering for the entire corridor would be completed in advance to keep the project aligned with Iowa Department of Transportation deadlines.
Traffic is expected to remain open during construction, likely with one lane operating in each direction. Temporary pavement would be used to route vehicles through intersections while roundabouts are built.
Engineers said access to corridor businesses would be maintained, but council members raised questions about how customers would reach those businesses, how traffic would be routed and whether additional right of way would be required.
The council also discussed ambulance and semitrailer access, drainage problems and the size of the city’s financial commitment.
Shared construction expenses such as pavement, subbase work and erosion control would be divided 60% to the Iowa DOT and 40% to Mason City. The entire corridor reconstruction has previously been estimated at approximately $50 million.
City Administrator Aaron Burnett previously estimated Mason City’s share at approximately $17 million when water and sewer improvements are included. Much of that amount has been placed in the city’s capital improvement planning, while officials continue seeking state and federal grants to reduce the local burden.
The Highway 122 West reconstruction is now included in the Iowa DOT’s five-year transportation program, allowing the first phase to begin as early as 2028.
The August 4 work session was for discussion and design review. No final construction contract was awarded and no formal vote approving the complete design was taken.