Runners travelling to Rickmansworth's Sport Relief Mile are being warned that major tree safety works will mean a main road will be closed on Sunday.
Riverside Drive will be shut on Sunday, March 23 and the following Sunday between 9am and 4pm.
In a statement released by Three Rivers District Council it was explained that a diversion will be in place to allow for the removal of a number of over mature Poplar trees.
Kevin Snow, council spokesman, said: "The recent extreme wet weather has meant that the trees root systems have been sat in water for an extended period and this has contributed to the failure of several of the trees in the vicinity already."
The council apologised for any inconvenience this may cause.
All other local roads including Park Road, the High Street and Church Street will remain open for the Rickmansworth Spot Relief Mile.