The Highway Traffic Act authorizes the province and municipalities to restrict truck weights during spring thaw to protect roads and highways:
- Spring weight restrictions may be applied to schedule 1 King’s Highways at any time during March and April, to schedule 2 King’s Highways during March through May, and to schedule 3 King’s Highways during March through June depending on local conditions and weather. A list of highways that may be affected is included in this [MTO memo]. Up-to-date information about actual weight restrictions can be viewed at: https://511on.ca/list/seasonalloads and carriers who use the listed highways are encouraged to carefully monitor this website. The 511 interactive map also provides up-to-date visual information – choose map menu item “Truck and Bus info”, then check “Seasonal Loads”.
- Municipalities may also pass by-laws and set dates when spring weight restrictions apply to specified roads under their jurisdiction. Watch for on-road signage.
- During Reduced Load Periods, weights are generally limited to 5,000 kg per axle, although certain exemptions apply as set out in Highway Traffic Act, Section 122: https://www.ontario.ca/laws/statute/90h08#BK217
- Unless otherwise specified on the permit, ‘annual’ and ‘project’ overweight permits are not valid during March and April in southern Ontario, and during March through May in northern Ontario.