Any street designated by ordinance as a yield right of way street and so posted is hereby declared to be a yield right of way street.
The driver of a vehicle in obedience to a yield right of way sign shall reduce the speed of his vehicle to not more than twenty (20) miles per hour, and shall yield the right of way to other vehicles which have entered the intersecting street either from the right or left or which are approaching so closely on such intersection as to constitute a hazard; but said driver having so yielded may proceed at such time as a safe interval occurs.
If a driver is involved in a collision at an intersection or interferes with the movement of other vehicle after driving past a yield right of way sign, such collision shall be deemed prima facie evidence of the driver's failure to yield right of way.