Enrollment In SchoolsShifted By 1-RoutesPopulation shifts attributed tointerstate construction have decreased enrollment at two elementary schools, brought about overcrowding at one, and increased the student population at two others here.The overcrowded situation exists at Oakwood School in South Hills, “We have them hanging on the walls,” Mrs, Alta Sloan, principal said. The school has 385 pupils this year. Last year there were 344.Mrs. Sloan said more desks are needed to accommodate the larger enrollment. “Right now we're making do with tables and chairs for some,” she said.Sharp decreases were noted at Bigley School where enrollment fell from 143 last year to 103 this week and Elk School where fhe total dropped from ZH to 239 for grades 1-fi. Both schools are In the path of 1-77.At Overbrook also in S o u t hHills, the student body increased from 337 last year to 383.Lakewood School in St. Albans also experienced an upswing in enrollment from 428 to 45B. An addition is planned for the building.Secondary schools appear to be in “good shape as far as building capacity and enrollments are concerned,M school officials said.Jake Moser, director of secondary schools for the county, said the enrollment picture might change after Labor Day, He predicted 180 to 200 late enrollccs.Senior high schools report a total enrollment of 13,341 as of Thursday. The figure is 71 below Iasi year's number.Junior highs have 13,524, also a decrease from tost year when tho total was 14,157.Elementary schools am to turn in Uieir enrollment figures Saturday.