The driver of a vehicle approaching a yield
sign shall be obedient to such sign and slow down to a speed reasonable
for existing conditions, or shall stop if necessary as provided in
§ 1172 of the Vehicle and Traffic Law, and shall yield the
right-of-way to any pedestrian legally crossing the roadway on which
he is driving, and to any vehicle in the intersection or approaching
on another highway so closely as to constitute an immediate hazard
during the time such driver is moving across or within the intersection;
provided, however, that if such driver is involved in a collision
with a pedestrian in a crosswalk or a vehicle in the intersection
after driving past a yield sign without stopping, such collision shall
be deemed prima facie evidence of his failure to yield the right-of-way.