Parents and children seemingly appear from everywhere. They crowd the Gulfton sidewalks with strollers and bookbags, as other mothers and fathers inch along in a slow-moving stream of automobiles stretching the entire block.The chatter of excited youngsters ready to jettison their books is interrupted by sharp whistles from the lone crossing guard trying to maintain order from the middle of the street. Walkers whisk through the intersection, followed by a burst of cars.