A survey of highway fencing along I-80 in Centre County, Pennsylvania, showed that 2.26-m (7.41-ft) type 3 modified fence has little value as a deterrent to vehicle-deer collisions; many deer crawl under the fence to the planted right-of-way, and the many gaps underneath provide easy penetration. From December 1974 through March 1976, numbers and position of deer were observed from a vehicle driven along 9.65 km (6 miles) of I-80 at night. Bimodal patterns of abundance were found. Deer were most numerous in spring and fall. Of 2577 deer sightings, 74.5 percent were on the highway side and 25.5 percent on the far side of the fence. Comparisons between a control area on the north side of the highway, where the fence was unmodified, and test areas on the south side, where gaps underneath were plugged or the top five wires were removed or repaired or both, showed that large numbers of deer crossed a fully repaired fence. Only six deer were reported killed during the 16 months of the study, and no live deer were seen on the highway. These results, relative to previous findings beginning in 1967, strongly suggest that high traffic volumes prevent deer from venturing onto the highway, thus reducing collisions./Author/