During the thaw period, roads are between 30 and 70% more fragile than usual, since their layers of granular materials are weakened by water accumulation at various depths. Overweight vehicles can cause significant damage during this period, and their impact is even more pronounced as their numbers have increased considerably over the past 25 years.

A slight reduction in loads can significantly decrease the damage to the road surface. That is why heavy vehicles are subject to load restrictions during the thaw period on roads managed by the Ministère des Transport et de la Mobilité durable (MTMD).

To safeguard public investments in Route Billy-Diamond, which is not subject to MTMD load limits, a measure was implemented in collaboration with carriers in spring 2021 to reduce the loads they transport during the specified thaw period.

This measure is needed because the geographical location and harsh weather conditions of Route Billy-Diamond make it particularly vulnerable to damage during the thaw. In spring, frost depth in the Baie-James region typically extends more than two meters below the road surface.

In order to monitor road thaw progress and determine the period during which carrier collaboration is needed, the Société de développement de la Baie-James (SDBJ) has installed sensors along Route Billy-Diamond and Chemin Chisasibi. Weather forecasts are also taken into account. The SDBJ conducts daily monitoring as soon as temperatures begin to rise close to the freezing point.

On Route Billy-Diamond, the start of the thaw load restriction period coincides with that of MTMD Zone 3. The MTMD road network management framework for the thaw period is also taken into consideration to establish the maximum load of heavy vehicles on Route Billy-Diamond.  


The primary heavy haulers planning transport on Route Billy-Diamond: Hydro-Québec, active mine operators and forestry companies.

Other heavy vehicle users, owners and operators, as well as shippers and transportation intermediaries, are also encouraged to follow the load restrictions below during the thaw period.



On Route Billy-Diamond, the start of the thaw load restriction period coincides with that of MTMD Zone 3. Visit the MTMD portal for information on the Zone 3 thaw period.


The load restriction period for Route Billy-Diamond comes to an end 35 days after the date that three of its seven sensors (six frost depth gauges and the Matagami road weather station) indicate a thaw to at least 90 cm in depth. This represents the time needed for the road structure to drain and recover its load-bearing capacity.

Past load restriction periods on Route Billy-Diamond

Start of thaw April 17MTMD Zone 3
End of thaw June 2TBD

Thaw load restriction period:

Axle and total load limits

To limit road degradation and protect the road network during the thaw period, Route Billy-Diamond users are encouraged to follow the same load restrictions as those required on roads managed by the MTMD. These load limits are prescribed by the Vehicle Load and Size Limits Regulation and presented in the Road Vehicle Load and Size Limits Guide


If you have any questions about the thaw load restriction period on Route Billy-Diamond, contact:

Affected carriers must promptly contact the Société de développement de la Baie-James if an emergency requires them to transport loads exceeding the thaw period load limits.

Gérard Djakou

Director, Road Maintenance Services

Société de développement de la Baie-James

110, boul. Matagami, C.P. 970, Matagami (Québec) J0Y 2A0

Telephone: 819 739-4717, ext. 1248, Fax: 819 739-4329

Pager: 819 638-2424 #8791, Cell: 873 995-1493