When looking at the curve installation, I think that you certainly need a lead-in area on each end; again you need to make sure the end points are in areas where the deer will disperse safely and not cross in a group. This is the place where some engineering is important.
The reflectors do not cast a light or reflection that will bother any homes or people. I have been out along the road edge at night to witness the reflection. It is barely visible and very transient. This is not a problem or even a potential problem based on my observations.
John Strieter can give you the exact cost for reflectors. But I was able to save installation cost by using our Sheriff's Work Crew. It does not take a lot to put them in once you have done the engineering, and you have had the underground utilities staked. You need the following people, materials and equipment.
Reflectors and bolts for mounting (again for a 2-lane road with 8-foot shoulders you need about 265 reflectors per mile.
One mounting post per reflector. I used the same posts we used for mounting delineators (those little reflective buttons you see along the road). Delineator posts are a little lighter (about 1.12 pounds per linear foot), and cheaper than regular sign posts. You will generally need 7-foot long posts, so that you can get around 2½ to 3 feet of embedment.
You can drive the posts with either a pneumatic or hand-driver (cheaper), plus hand tools for tightening nuts and bolts.
You will need cone traffic control signs when working along the road. How many and where you need them will need to be approved by the local road authority.
A pick-up or small truck to carry equipment and materials and crew, with flashing lights.
A two-person crew is enough to install them but you may need as many as two-more people if the road agency requires flag-persons.
Cost benefit
Last year (2008) an agency in Michigan calculated a cost of $18,000 to $25,000 per mile for installation using a County sign installation crew. I made an estimate for installing 265 reflectors and it is in the table below. I tried to be conservative (on the high side) and you can add or subtract as needed.
Materials (reflectors, posts, hardware, traffic control signs)
$17,870
Labor (two-person crew)
$2,385
Equipment (small truck, post driver)
$1,325
The total is $21,580 so the cost per reflector was $81.
In terms of cost benefit, the average cost for damage to vehicles per car deer crash is about $2,500. I experienced 75 to 95% reduction in my County so if we use a 75%, again to be conservative the numbers look like this:
◦ If we have a one mile section.
◦ If we have an average of 10 car deer crashes per mile per year on the section.
◦ If we install the delineators for the cost of $21,580
◦ If we experience a reduction of 70% (eliminate 7 crashes per year)
Then, we eliminate car damage of 7 x $2,500 = $17,500 each year.
If we divide installation cost by annual car damage saving we have $21,580 / $17,500 = 1.23 years for payback. In other words, the installation costs are paid back by crash damage cost savings in 1.23 years. This is a very quick and reasonable rate of return in the traffic engineering business.
If we eliminate only 30% (3 crashes per year) we still get $21,580 / (3 x 2,500) = $21,580/ $7,500) = 2.88 years for payback. In other words, the installation costs are paid back by crash damage cost savings in about 3 years. This is a typical payback period for safety projects.
End conditions
The conditions at the ends of a particular installation are very critical. I did not experience any problems with deer crashes clustering at the ends of our reflector lines. However, we were very careful of where we ended them.
Generally, you need a place where deer will disperse and not have a natural desire to cross the road. We generally ended the delineator lines at major intersections which seemed to work well. We also ended them by bridges or places where there were clusters of homes. In one case we ended them by a cemetery and for some reason that worked very well. I think to a large extent it is a common sense thing, and needs some people who know the local deer herd and deer behavior to be in on the initial engineering to pick the spots where the reflector lines start and end.
Deep snow on the ground
As far as snow is concerned, first I would look at the crash data to see when the most critical time for car-deer crashes is. In Calhoun County our peak car-deer crash periods did not happen when we had a lot of snow on the ground, and we noticed that during high snow periods, deer movements tended to be down. While there certainly would be crashes, they were not the problem compared to November or even during harvest time or in the Spring and Summer.
In any case, if snow season is a concern, the bottom line is to remember that first the reflectors need to be visible, and secondly, they need to reflect light where the deer stop by the side of the road before crossing. If your delineators are going to be buried by snow, then I would say digging them out is not reasonable. If they are not buried, then remember that besides reflecting in a horizontal direction (along the roadside), there is also a vertical component to the reflection that will account for some elevation change due to snow. Again, the upfront engineering can look at this aspect, and it is mainly common sense. But again, we need to determine if winter crashes are the problem and then make our design fit the need. If you can get a reasonable payback by just reducing crashes during non-snow times then I would say go with it, understanding that no method works 100 percent all the time with the same effectiveness.
Conclusion
As long as the reflectors are able to reflect headlight beams to where the deer are going to be coming out to cross the road they, will work. That is the bottom line. If the deer cannot see the reflected beam, or reflectors are missing (or buried) in the snow they cannot work.
Dennis Randolph
Managing Director/County Highway Engineer
Calhoun County Road Commission
Marshall, Michigan
April 7, 2009
