Last minute changes
These are the bane of all race directors. Yet, organizers need to be prepared for late surprises.
The Dexter-Ann Arbor Run, in Ann Arbor MI, had to change its course barely two weeks before race day because of road construction.
Other events have had to make changes because of storms, floods, construction projects, competing tourist attractions, and other reasons that were not evident when the race was planned.
The now defunct Walter Payton Sweetness Run, in Aurora IL, had the foresight to certify two courses for both its 5k and 10k. That act came in handy when the nearby Fox River flooded the planned course. The race ran, instead, on the alternate course.
Have contingencies in mind, even if you never have to implement them. It will help you deal with last minute changes that cannot be avoided.