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The Regional Municipality of Durham printPrinter Friendly Version

Public Service Announcement

Extreme temperatures cause sunken maintenance hole covers

WHITBY, ON February 19, 2015

The Regional Municipality of Durham, Works Department would like to advise motorists that due to extreme temperatures this winter, there has been significant pavement heaving, resulting in “sunken” maintenance hole covers (also known as manhole covers) on Regional roads. Motorists are reminded to exercise caution when approaching sunken maintenance hole covers on roadways across Durham Region.

Due to extreme winter conditions, the frost has lifted paved roads, causing maintenance hole covers to appear as if they have “sunk.” It is actually the road that has raised around the maintenance hole covers, because of the moisture content in the road base and exposure to prolonged cold temperatures.

Maintenance hole covers have deep foundations, located below the frost line, and do not heave with the pavement, due to temperature fluctuations. Maintenance hole covers cannot be patched the way potholes can, as material will not bond to cast iron. In addition, access to maintenance holes is required. The road should settle back to its original elevation, as the frost thaws, with warmer spring temperatures.


The Works Department is responsible for year-round maintenance on Regional roads. Regional roads are the main arterial roadways in Durham, and can be identified by their Regional road numbers (RR#) on street signs. A full list of Regional roads can be found at If a road does not have an RR#, it is probably maintained by the local municipality (this includes most residential and side streets).


Motorists are reminded to exercise caution when approaching “sunken” maintenance holes. The Region of Durham regrets any inconvenience this may cause, and reminds motorists to drive according to road conditions.


Sunken maintenance hole covers are not the same as potholes. The Region of Durham takes pride in the maintenance and care of Regional Roads, which are monitored for potholes, debris and other safety/maintenance concerns. Residents with concerns about potholes on Regional Roads should contact their local Durham Region Works Department Depot. Depot contact information is available at Depot staff will repair reported potholes as soon as possible. For more information on road maintenance in Durham Region, visit

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For more information, please contact Corporate Communications.