Answer: IMPASSABLE

AnswerCrossword Clue
IMPASSABLEDescribing traffic-jammed roads.
IMPASSABLEInsurmountable.
IMPASSABLELike some roads after blizzards
IMPASSABLEWith no way to get by, fish turned up caught by spear (10)
impassableImpossible to travel along or over
impassablethat cannot be passed