# Mileage on Deer Crossing signs **URL:** \ **Category:** Factual Questions\ **Created:** [March 19, 2009, 3:54pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032 "2009-03-19T15:54:09Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [March 19, 2009, 3:54pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/1 "2009-03-19T15:54:09Z")
Moved into the Hudson Valley a few years ago. There are deer crossing signs on highways with absurdly large mileage notices, as in “Deer Crossing: 42 miles.” Aside from the obvious joke about the signs in the first place (“how do the deer know to cross at the signs?”), where do the numbers come from and what good do they do? ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [March 19, 2009, 5:20pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/2 "2009-03-19T17:20:53Z")
Believe it or not, those signs usually aren’t just placed randomly. Usually they’re placed either in areas with higher than usual car-deer collisions and/or at actual deer migration routes determined by wildlife people. The good they do is you know to be on the look out for deer and slow down, especially if you’re driving there at sunrise or sunset when deer are more likely to be on the move. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [March 19, 2009, 6:05pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/3 "2009-03-19T18:05:17Z")
Right, that’s the real answer to the canard “how do the deer know to cross there.” Deer are creatures of habit, and it’s easy to find deer paths in the woods about the house. I get deer crossing signs in general. What I don’t get is the “Deer crossing: **42** miles” bit. The mileage isn’t universal – some say 17, some other numbers – given how rigid civil and highway engineering codes are, is there some formula to determine what number to use? Picked out of a hat? Also, what is the rational behind a 42-mile warning? ---
**Author:** ![MadTheSwine](https://avatars.discourse-cdn.com/v4/letter/m/9fc29f/32.png) [@MadTheSwine](https://boards.straightdope.com/u/MadTheSwine)\ **Post date:** [March 19, 2009, 6:18pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/4 "2009-03-19T18:18:11Z")
This may be a dumb question but…you do understand they mean deer crossing the next 42 miles right? Not in 42 miles Just making sure. ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [March 19, 2009, 6:58pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/5 "2009-03-19T18:58:00Z")
> [@Rhythmdvl](#): > > Also, what is the rational behind a 42-mile warning? It’s to save them putting up signs every x miles for 42 miles. ---
**Author:** ![EmAnJ](https://avatars.discourse-cdn.com/v4/letter/e/d2c977/32.png) [@EmAnJ](https://boards.straightdope.com/u/EmAnJ)\ **Post date:** [March 19, 2009, 7:14pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/6 "2009-03-19T19:14:58Z")
As stated, it means for the next 42 miles, be aware. It’s probably a migratory area. ---
**Author:** ![Arkcon](https://avatars.discourse-cdn.com/v4/letter/a/96bed5/32.png) [@Arkcon](https://boards.straightdope.com/u/Arkcon)\ **Post date:** [March 19, 2009, 7:45pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/7 "2009-03-19T19:45:33Z")
I always figured, there’s something like, a steep cliff, or an impassible river, that has just ended, where they put the sign, and will start up again, 42 miles later. Deer can’t cross before the sign, and must cross somewhere within 42 mi, because of some physical reason that someone in a helicopter can see is obvious, not because the deer can read the sign. Look up the area on Google maps and see if the reason why is obvious to you. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [March 19, 2009, 8:31pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/8 "2009-03-19T20:31:37Z")
> [@Arkcon](#): > > I always figured, there’s something like, a steep cliff, or an impassible river, that has just ended, where they put the sign, and will start up again, 42 miles later. Deer can’t cross before the sign, and must cross somewhere within 42 mi, because of some physical reason that someone in a helicopter can see is obvious, not because the deer can read the sign. Look up the area on Google maps and see if the reason why is obvious to you. Thanks – that’s getting to my curiosity. Half the question is basically: why don’t they just put up big pictures of Darwin on the side of the road? Your on a highway, in rural New York… There Will Be Deer. If someone doesn’t realize there is wildlife out there, a sign they passed forty minutes ago isn’t going to help them. The other half was how do they determine whether to put 1, 3, 5, 7, 11, 13… miles on the sign. Google Map 87 as it heads from the City to Albany, and there aren’t many places where deer can’t get to. How’d they figure “42” would be a good number to put on the sign? ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [March 19, 2009, 8:48pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/9 "2009-03-19T20:48:55Z")
> [@Rhythmdvl](#): > > The other half was how do they determine whether to put 1, 3, 5, 7, 11, 13… miles on the sign. Google Map 87 as it heads from the City to Albany, and there aren’t many places where deer can’t get to. How’d they figure “42” would be a good number to put on the sign? Go back and read post #2. Accident statistics have probably told them that the next 42 miles are a high-risk area. ---
**Author:** ![Gfactor](https://avatars.discourse-cdn.com/v4/letter/g/9de053/32.png) [@Gfactor](https://boards.straightdope.com/u/Gfactor)\ **Post date:** [March 19, 2009, 8:58pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/10 "2009-03-19T20:58:32Z")
> [@Rhythmdvl](#): > > How’d they figure “42” would be a good number to put on the sign? They do studies. If the frequency of deer-vehicle accidents shows a cluster of accidents within a 42-mile (I’ve never seen one for that long of a range) then they put a sign up that says “deer crossing, next 42 miles.” [http://www.wcroads.org/services/traffic/signage.htm](http://www.wcroads.org/services/traffic/signage.htm) > [@](#): > > These signs are being upgraded as time and funding allows to indicate > the length of roadway that has high deer accident numbers (e.g. next 3 miles). [http://www.mwcog.org/uploads/pub-documents/y1lYWA20061030150157.pdf](http://www.mwcog.org/uploads/pub-documents/y1lYWA20061030150157.pdf) (pdf page 67; document page 57). ---
**Author:** ![Gbro](https://avatars.discourse-cdn.com/v4/letter/g/c6cbf5/32.png) [@Gbro](https://boards.straightdope.com/u/Gbro)\ **Post date:** [March 20, 2009, 4:55pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/11 "2009-03-20T16:55:35Z")
Then it can be the result of a political agenda. A good friend of mine was a councilmen. Someone brought up the idea that the state should put up a D C sign by their city and the state is in charge of said roadway. The State refused as the numbers didn’t meet their qualification, but then because this council wouldn’t relent, the state did. Today there is another of those meaningless signs along the road.:smack: ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [March 20, 2009, 5:01pm UTC](https://boards.straightdope.com/t/mileage-on-deer-crossing-signs/490032/12 "2009-03-20T17:01:40Z")
Thanks for the links **Gfactor**. That’s exactly the background I was curious about. E.g., from [wcroads.org](http://wcroads.org): > [@](#): > > Procedure > > A deer-car accident history should be researched for the stretch of road in question. Installation of deer Crossing signs is warranted if five deer car related accidents have occurred in a twelve month period. Placement of the signs should be reviewed every third year. Any necessary adjustments in the placement or removal of the sign should be made according to the following guidelines: > > [ul] > [li]A deer-car accident study should be conducted for the stretch of road encompassing the deer crossing area and one mile to either side of the area.[/li][li]The placement of signs shall be adjusted to reflect any change in the concentration of deer-car accidents in the study area.[/li][li]When the accident study shows that no deer-car related accidents have occurred in the study area in a minimum of twelve month period, the sign may be removed at the discretion of Washtenaw County Road Commission.[/li][/ul] The political thing certainly weighs in too.