"Flooded roads" means that there is so much water covering the road that it becomes difficult or impossible to drive or walk on it safely. Full definition
If you are driving during a hurricane to get home or during heavy rain period you want to be sure to avoid flooded roads. (autoinsuresavings.org)
Sandbags arrived after the floodwaters, and hundreds of cars were abandoned on flooded roads because highway authorities were not alerted early enough to close the roads. (newscientist.com)
That growing population has flooded our roads with cars and overwhelmed our public transportation solutions. (southhondamiami.com)