On Monday, Feb. 26, the N.H. Department of Transportation began posting state highways, limiting the use of heavy trucks to reduce the breakup of pavement during the transition out of winter.

The posting is the unofficial start of mud season, when the extreme warm/cold cycle causes frost heaves that heavy trucks can demolish, and also breaks up dirt roads to create mud season.

Feb. 26 is early for the posting, which since records began in 2005 has most often happened around the second week of March. But it’s not a record: Last year the posting occurred on Feb. 17, the earliest on record, and it has happened in February in three other years.

The maximum allowable vehicular weight on posted sections of state highways is 30,000 pounds gross weight, or the cumulative width in inches of all tires contacting the road surface multiplied by 300, whichever is less. Under state law (Section 236:3-a), trucks carrying home heating oil, processed milk products, maple sap, and septic pumper trucks are exempted from seasonal bans with the approval of NHDOT District Engineers.

Affected roads can be found at newengland511.org/ under the top banner “Trucking – New Hampshire - Seasonal Posting.”