Cars do hit deer; however erecting fences is one way to prevent deer from crossing roadways.
Every review of accident prevention methods over the last 20 years in both the U.S. and Canada has demonstrated that well designed and maintained fences, used in combination with one-way gates and under-and-over passes, is the most effective method of averting these accidents. The reduction in such accidents at sites that have implemented these measures has ranged from 77-95%. There are different types of fencing available that can be either temporary or permanent and vary in a number of ways (e.g. cost, level of protection provided and amount of maintenance required to be effective).
Another effective option is the Strieter-lite system, which uses reflectors to create a strobe-like effect that deters deer, and other animals, from crossing a road until an automobile passes. The Strieter-lite system has been installed in several states (e.g. MD, NJ, NY, VA, WA). This system has greatly reduced the rate of these collisions. An evaluation of the Strieter-lite system demonstrated reductions in the number of collisions per mile per year by 78-90%. Installation of the Strieter-lite system is eligible for 90% funding under the Federal Highway Administration, Highway Safety Improvement Program and matching funds for installation may also be sought under the Transportation Equity Act for the 21st Century.