In the colder parts of Virginia arborvitae do better. Japanese ligustrum (evergreen privet) do better in the warmest parts of Virginia. Illicium parvifolium http://www.finegardening.com/plant/yellow-anise-illicium-parviflorum

is another good choice.

You can reduce the sight of the traffic, but plants won't reduce the sound. Only a solid fence will do that.

Do you really want to be up on a 10' ladder pruning your hedge every year? Wouldn't a slightly shorter height block sight lines for you and require a somewhat shorter ladder? Larger gardens with 10' hedges may use a lift truck to do the trimming, but I can't imaging you would want to do that.

There are some arborvitae that remain relatively short, in the range of 10' or less over a number of years. How they grow together depends on the width of that particular cultivar and the spacing you use to plant them. However, many types of arborvitae are deer favorites, so if deer are common in your neighborhood, they may leave you with lollipop trees with the lower greenery eaten.

Privet is invasive in many areas, and if it is in yours (check with your state dept of natural resources or the equivalent) it will be seeding into all possible areas in your yard and your neighbors yards and any parks and wild areas where birds fly to and deposit the seeds. I can remember as a kid in zone 6 Ohio having to pull privet seedlings from neighbors' plantings. I also haven't seen privet hedges that had the density of most conifers, though that may be either the species I have familiarity with or poor pruning practices.

Are you willing to consider other plants?

Privets in New Hampshire are different than Ligustrum japonicum, which is evergreen & non-invasive in Virginia.

Thank you for the insights! I am definitely open to other plants. I am really just looking for something that will grow in full and be able to be shaped. We have deer (I mean, it's Virginia), but they don't often venture this close to the road.

imo .. pruning is done by hand.. very selectively .... and shearing is done with a power tool ...... or those giant scissors.. i cant think of what they are called ...

to repeat ... to shear a hedge at ten feet ... you will need to get waist high to ten feet ... to shear comfortably ...meaning you are going to have to climb and work at 5 to 7 feet .... so you will need a ten to 15 foot ladder .. we dont really want you standing on top of a common household 6 foot ladder ...

now.. when you are up there ... you might be able to shear a 2 to 3 foot area .. however far you can reach.. without leaning off the ladder .... and then climb down and move the ladder ... repeat ad nauseum ... until done with one side ... and if you grow it thick ... start again on the other side ...

and my biggest caveat is ...what might be physically easy when you are young ... in 10 years.. 20 years ... will you still be able or willing to do the job ...

btw .. if you plant a deer attractive plant.. deer will find it .. dont buy that they arent there now.. so they wont go there after you plant a salad bar ...

im not sure you will find plants that grow 1 to 2 feet per year ... and then slow down and be manageable at ten feet ... [and on rereading.. how will the hill work with the ladder ...]

how about a big city name... for a more precise location ... and a couple pix might really help us brainstorm for you ...

ken

Here is another excellent choice if you are in the warmer parts of Virginia....https://www.diynetwork.com/how-to/outdoors/gardening/chindo-viburnum

I am about 2 hours southwest of D.C. Here are some photos of my property. Perhaps a type of shrub to go with the old-and-haunted vibe I have going on?

As far as placement of your plants, due to the power lines and trees, I would plant them slightly to the road side of the crest of the slope rather than right under the power lines. You don't want to lose a lot of height because of the slope, but also you don't want to have them sparse due to shading from the trees or be hack back by the power company. If you chose a type of plant that doesn't need a lot of pruning, that will be better, but I don't have familiarity with plants in your area. Do you plan to bring the hedge up the sides of the property towards the house, perhaps at a lower height, or have a fence, or . . .? I think a row of shrubs only parallel with the road will look a bit odd.