Obsolete method
Figure 1
The "original" method
From the time period 1978 to 1986, the Swareflex Division of D. Swarovski and Co., Austria, prescribed that the reflectors be mounted on posts every 20 meters along each side of the road and directed away from the highway as indicated in Figure 1.
The 20 meter spacing was more or less based on a recommended average of most situations. As you can observe, this method resulted in many "blind spots" or open areas from the fields of vision that were not protected by the reflectors.
Figure 2
In hind sight, this was a mistake because many installations and tests were conducted following these original instructions. In fact, there are quite a few installations even today that are still installed under those original instructions.
Consequently some of the results have been less effective, especially where trees and vegetation were in close proximity to the highway as shown in Figure 2.
However, this "former" method has worked effectively where wide open spaces exist along the roadsides. One very successful test attesting to this was the 1986 Minnesota Wildlife Report 3, DNR, conducted on I-94 near Sauk Centre from 1980 to 1984 reporting a 91% reduction.
Another test was the August 1984 WSDOT Report WA-RD 64.1 conducted on SR 395 in Eastern Washington State from 1981 and 1984 reporting an 89.7% reduction.
Besides these, many similar installations have shown excellent results in Austria and Germany.
But, there is a better way!
Figure 3
The Strieter-Lite reflector installation method is shown in Figure 3.
This method provides complete coverage of not only the roadsides, but also the highway itself.
Figure 4
In comparison with the old method, note in Figure 4 the improved complete coverage especially where trees and vegetation are in close proximity to the highway.
Figure 5
If roadside conditions permit, the reflectors can be offset up to 12 meters (40 feet) from the edge of the road as set forth in Figure 5.
Figure 6
Figure 6 illustrates a variation of the original installation method where the reflectors are mounted back-to-back on a single post located on just one side of the road.
As indicated, at least one roadside is protected with this method. However one half of the road and the other roadside remain unprotected, especially if vegetation is in close proximity.
Recommendation - use the current installation method
Unfortunately many of the early published reports which have concluded that the reflector system is not effective, used the original installation method of directing the light away from the highway as shown in Figure 1. Since it was the only installation method known at that time, no comment was made and therefore to a casual observer or a researcher, the system has been and is still reported as being ineffective. It is important to read these reports very carefully to isolate the more recent results.
We have found by actual tests that the Strieter-Lite system, when installed correctly as shown in Figure 3, has indeed been effective with reductions as high as 100%. We hope that this will clarify the situation on many of the adverse reports and that you will consider using the Strieter-Lite reflector system as an effective and economical system to reduce the tragic nighttime deer/vehicle accidents.