CR4 and 9th Line Innisfil Roundabout

The County of Simcoe is constructing a roundabout at the intersection of County Road 4 (Yonge Street) and 9^th Line in Innisfil.  The roundabout will have a two lane configuration to accommodate the future widening of County Road 4 to four lanes (two lanes per direction of travel).  Benefits of the roundabout include improved traffic flow, increased traffic capacity, and enhanced safety due to lower vehicle speeds and fewer vehicle conflict points.  The County will be coordinating with InnServices to install water and sewer mains during road construction.

Timeline

• Utility relocations: Winter 2024/2025
• Tender release: Spring 2025
• Construction start: Summer 2025

Construction began in July 2025. Final roundabout work, including the concrete curbs and splitter islands, top course asphalt, and permanent line painting, is scheduled for completion in Spring/Summer 2026.

Impacts to Drivers & Neighbours

The intersection of County Road 4 and 9th Line will be fully closed to facilitate paving operations from 7:00 a.m. on Wednesday, August 26, 2026, until 7:00 a.m. on Friday, August 28, 2026. Access to local residences and businesses will be maintained throughout the closure.

This closure is necessary to complete intersection improvements being undertaken by the County of Simcoe and is anticipated to be the final major disruption to the local community associated with this project.

During this period, a clearly marked detour will be provided via McKay Road, County Road 21 (Innisfil Beach Road) and 10th Sideroad.

To view the Notice of Closure, including additional details and a map of the detour, please click here.