We have one built into a ford explorer that is used for runway inspections during storms.
To tell the truth, I'm not sure what any of it means, nor do I think anyone else where I work. I think its more of a neat gizmo more than anything else. I'm sure someone out there understands what it all means, but to me, if its snowing and the snow is sticking to the ground, then what else do you need to know.
I have read some article though, and I guess a good use is for applying chemicals. Read some article on crew in germany, and they use them to determine when/how much/and what type of chemical to use on their roads. It was quite interesting. They are supposely saving a fortune in snow melter costs now because of them being mounted in every truck. They train all their drivers on what numbers mean and therefore they know that (unlike here in NJ) that spreading a load of salt will do nothing and is not needed.
I guess the main thing is that sometimes air temps can greatly vary from ground temps. Therefore, before a storm, drivers can compare the two and decide whether or not to start spreading or to hold off. A big problem because tons of chemicals are waisted each year when they weren't needed.
If it starts to snow, and ground temps are no where near freezing, then no salt may be needed. Before, drivers would start spreading when the first flake hit the ground, and then, an hour later when the snow stopped and past, would have just waisted thousands of dollars of chemical that weren't needed.
The big benefit is when a truck covers a large territory. Some areas, the ground temp may be low, therefore needing a application, while 6 miles down the road, the road temp may be high, and may need nothing. While driving down a interstate, they monitor the ground temps, and if the numbers show a increase, they may stop spreading. Then, a few miles father down, temps may drop again, so the turn the spreader back on. I guess its kind of a way to 'spot treat' a snow storm. Its easy to see how this could save a LOAD of money over the old method of 'spread everything everywhere'
I would be interested too in the method and 'science' of how to read temps. I understand the theories, but just can't add the numbers up. As for the usefullness in a residential/commercial aspect, it may be limited. It seems like one of those 'big boy' municipal gadgets. I'd hate to get in a argument with some owner, explaining a book on 'the physics of snow' to them while they are bitching at you on why there lot is not salted yet. Seems like a losing battle still.
We have a Road Watch system in both of our salt trucks. It does help us to determine how much salt to apply--depending on the surface temp. It seems like air temp and surface temp usually stay within a couple of degrees of each other when there is snow on the ground. It is also a great marketing tool--you can tell your custmers that you are able to judge when to salt and how much to salt, or not apply any at all.
That system you heard about actuall comes from the Canadian Air Force. We've just adopted it this year. I can send you their demo CD if you e-mail me with your address, its pretty cool.
Anyway, we have a friction tester we use nightly here in Germany. (I'll take some pics this week)
We also use GPS on all airfield maintenance equipment now (its part of this system). The good thing about that is that we don't have to read any of the reading off the friction tester, the GPS system reads the tow vehicle and logs the location of the readings. I can tell you the temperature on any 3'x3' section of runway, taxiway, or ramp at any time. It sends it all back to a color coded map of the airfield on the PC. Now when we send out our de-icers, all we have to do is tell the guys which area to drive in and the computer tells the de-icer how much chemical is to be released and where and when! All this was really confusing at first, and none of us wanted to deal with it, but we thought about how uch money (hundreds of thousands) were involved so we couldn't just throw the whole system in the dumpster like we wanted. Now that we have it figured out its great, no matter how stuuuupid are drivers are, we know they're not wasting material on dry areas, or places that aren't going to freeze, etc.
We are supposed to save 45% in chemicals this year.
The other part of this Snow and Ice Management system is the EPOKE spreader I told you guys about that runs off a wheel under the spinner with a shock so it always has traction. No central hydraulics, no aux engine. It has chemical capability too. You can spread chemical and dry at the same time. This way it activates your dry product on the way to the ground and will help it stick instead of blowing all around on the ice.