For our last WTF of 2014 back in December, we noted that many of the questions we receive from readers have to do with roads, and we included a sampling of them that we hadn't yet investigated. Turns out, peeps over at the Vermont Agency of Transportation had a good time addressing the questions — when they weren't busy plowing, presumably — and were kind enough to share their answers with us. (Our thanks to media contact Erik Filkorn and deputy chief engineer Kevin Marshia for compiling them.) We divvied the readers' questions up into two parts, the first of which you can find at sevendaysvt.com. Here's the second.

This is a perennial question:

I know the salt is bad for the car and for my dog's little paws, but how bad is it? I'm curious to know what the environmental impact of all this salt is, how much is used every year, and if the benefit of using salt outweighs the negative impacts.

VTRANS: Road salt is the same as the salt on the dinner table, NaCl, just bigger particles and not as clean. VTrans uses about 100,000 tons of salt per year on our highways statewide, based on a five-year average; last year we used more than two million gallons of salt brine. But with three severe winters in a row (including this one), those numbers are growing.

At times VTrans will mix additives into dry salt or salt brine to make it work better at lower temperatures. We use a product called Ice B'Gone (IBG) that is essentially water, molasses and magnesium chloride. IBG also makes the salt or brine sticky so it stays on the road better. Our own field-testing and that of other organizations has determined it to be less corrosive than salt. In fact, the Environmental Protection Agency rates IBG as "designed for the environment."

The problem with additives like IBG and other salt alternatives is the cost. It costs 10 times as much as salt brine. When all is said and done, there is no more cost-effective way to melt snow and ice than good old-fashioned road salt.

As for environmental impact, the bottom line is that road sand and chlorides are having a growing detrimental effect. When we allow sand and salt into our water ecosystems, it doesn't break down or disappear; it stays there until it's removed. Since large-scale removal is not technologically or economically feasible, it behooves us to limit the amount of sand and salt entering the environment.

In fact, it's become such a problem that, in a year or two, we expect to be faced with a new federal regulation on the total maximum daily load of chloride; it will mandate that certain actions be taken to reduce chloride discharges to surface and ground water. VTrans is ahead of the curve, as the agency has taken steps to reduce usage in the application phase of chlorides. But we definitely have more work to do on how we store materials and manage our brine production/waste recovery-reuse process.

We will also need to get a better handle on how and where we wash trucks in the winter to minimize discharging chloride-laden wash water. Towns will be faced with the same challenges.

The other big issue with chlorides in the environment is corrosion. Simply put, salt — whether dry or brine — is corrosive.

The Margaret Chase Smith Policy Center at the University of Maine also tackled this. It concluded that the total number of chlorides in the environment has a much stronger influence on metal corrosion than the type of chloride-based de-icer or the method of application.

We believe that by continuing to actively manage our storage and usage of chlorides, we can limit how much we introduce into the environment. But we are under constant fire from impatient winter drivers who want us to use more and more salt and sand so they can go faster during winter storms.

Interestingly, we continue to see more highway fatalities in the summer. This tells us that, no matter how much salt we use, there will always be people willing to drive too fast for conditions and put themselves and others at risk.

Some readers are flummoxed by Vermont's highway markings.

What about the exit-numbering system, sequential versus more common/standard way of using mile markers?

And...

When is Vermont going to enter the 21st century and renumber our interstate exits by mile marker?

VTRANS: This is a story where timing is everything. Back in 2009, federal requirements were passed mandating that each state move to the new mileage-based exits, but we were right in the middle of replacing our signs to bring them up to current retro-reflectivity standards (very shiny). We'd already made all the signs, and it seemed wasteful to trash them, since they're supposed to last about 15 years.

Changing to the mileage-based numbering system is going to mean changing a lot of other things. If you're a business with an exit number in your name, or if you make tourist maps, you should be planning your letterhead order so that it runs out around 2020. VTrans plans to do a lot of work with the regional planning commissions and chambers of commerce on this front in the coming years in advance of the rollout, as it will be a culture shock to some.

Another reader is looking for a quicker way to get into and out of South Burlington.

Since I-89 connects to I-189, and I-189 connects to the south end of Dorset Street, why no access to and from the south end of Dorset Street to and from I-89 via Exit 13? Seems it would relieve much of the congestion in the clusterfuck at Exit 14 by those who could take Kennedy Drive and bypass Williston Road.

VTRANS: Yes, this would seem simple enough. And it might be, if we were in the middle of a big, empty salt flat in Utah. But this is a pretty densely packed neighborhood with a lot of things going on, including homes, businesses and sensitive environmental areas.

This has been discussed off and on for many years. If we were to upgrade the interchange, the Federal Highway Administration would require us to upgrade to "full service," providing northbound and southbound access to I-89 from Dorset/Kennedy as well as southbound I-89 access to the same. In other words, we can't just do one ramp; we would have to do one serious Hot Wheels track.

This also ties into an ongoing discussion about a new ramp system at I-89 and VT 116 (commonly referred to as Exit 12B, though that would change after 2020, if you're keeping score), just down the road. So it becomes a much larger discussion about land use, traffic management and economic growth. The Chittenden County Regional Planning Commission has a wealth of information on this at ccrpcvt.org.

And finally, another exit oddity.

Why does the interchange where I-89 meets I-91 in White River Junction have no number? It is the only unnumbered exit in the entire U.S. interstate system that I can recall coming across. ... When the roads were built, did someone just forget, and start the numbering at Quechee?

VTRANS: We checked with one person here who was around when the interstate was built, and it's something of a mystery even to him. Northbound on I-91, the interchange is Exit 10, but it couldn't be named Exit 10 southbound on 89, or it would be in conflict with Richmond. In looking at the route logs, the sketches clearly show Ramp A and Ramp B, but not any exit number. While Vermont is one of a kind in many ways, you only have to travel as far as Concord, N.H., where I-89 meets I-93, to find a similar situation. We'll keep researching it because now we're curious, too.