Trees hardly block noise at all. Ever notice how when you are in the woods vehicles that are a fair distance away sound like they are right on top of you, despite perhaps hundreds of trees between them and you? That's why the state has been putting up high concrete walls between freeways here and adversely impacted urban properties. You need something like a concrete wall or an earthen berm to block noise noticeably.

But equally, a good barrier of trees does have a distinct psychological effect - the noise may be just as loud, but you don't notice it so badly if you can't see the vehicles.

Something like a double row of Arizona Cypress, or maybe Coast Redwood, should work.

Resin

Swamp Chestnut Oak (Quercus michauxii).

Bboy is right. There's a bunch of high concrete walls in Houston between freeways and residential areas.

Anyway, you can't do wrong with Montezuma cypress. Amazing fast growth for such quality trees that will almost stay evergreen in your location. Of course, you just have to find them.

I have an idea. Try 'Nanjing Beauty' which is a cross between bald and montezuma. Thick foliage. Fast growth. Very nice green color. You can purchase them at Botany Garden Shop pretty cheap if purchased in bulk (5 or 10?) at half price off.

I agree with bboy that trees don't block the noise of traffic much at all, however at least you won't see it with a hedge of trees. I don't know how much you hope to spend, however planting oaks the length of 400 feet won't be cheap. While not the most desirable of trees, a hybrid poplar or a hybrid willow will grow fast, and fill in a dense hedge in five years. Plus they are very cheap. Most major nursery catalogs sell them. Every tree has it's purpose and while I wouldn't plant one in my front yard, a hedge along a highway one quarter mile away is the perfect use.

Willows or poplars won't last very long; if used, something else more permanent will need to go in at the same time to replace them when they fail.

How important is year-round cover? The traffic will be visible through deciduous trees in winter.

Resin

Mexican white oak (Quercus polymorphia;evergreen) is supposed to be fast grower. Texas Forest Service sells them by bundles.

Eastern red cedar would provide round year screening.

Thuja Green Giant is another evergreen option that grows fast.

I suggest using either Longleaf or Slash pine (no Loblolly), and then underplanting with evergreen shrubs like yaupon holly and azaleas. You could mix some Magnolias in there too. The pines may appear to just sit there the first year while they get established, but beginning the second year they will take off. They are native and grow very well here in south Alabama, and they will in south Mississippi too.

Eastern Red Cedar would work and is native. So would Magnolia.

Making your barrier as wide as possible, with at least 3 layers, will help also, at least 2 layers being evergreen. A mix of trees at the back, and shrubs at the front will help, too. Plan on making it at least 40' wide, maybe 50-60', to allow for the growth of the trees/shrubs, in staggered rows. While the above posters are correct that even 3-4 layers of trees won't totally block the sound, they will mute it somewhat, and the visual barrier will help too.

Planning on having a fairly loudly burbling fountain (or more than one) at that the side of the house, outside the windows that are the most exposed to the road, will also help block, and limit your perception of, the noise from the cars.

thanks for the suggestions, it gives me a few things to look into. i know the trees won't block all teh noise, but at that distance and no more traffic than there will be, it should make it tolerable. i do want it to be pretty much evergreen trees, and already have a couple of mature magnolias, so they may be an option to at least throw int eh mix. have a few cedar and cypress trees on teh property as well, so some of them may work.

budget is tight since we just had a new baby last week. even if i have to go with cheap trees that will only last 10 years i may have no other choice.

Plant cheap trees which will last about 15 years, also mix into the design plenty of quality, moderate to almost slow growing trees. This way, when the cheap trees become an eyesore and need to be removed, the area will still have some very nice trees still growing. Also, keep in mind that as the cheap trees age, it will be a good idea to periodically plant other young trees near the cheap trees so the young ones can be established and growing well by the time those cheap trees need to be removed.

Of course 3 years is not long enough time for even your fast growing trees to be mature enough to provide the sound muffle or sight distraction you desire. So Consider seriously planting a view blocking hedge near any sitting areas, and also incorporate into the design a significant waterfall structure in which water falls from a ledge that is constructed for the water to be falling from a 6-8 feet height. The waterfall can be designed to let the water fall into a pool or pond with a pump in the bottom which recycles the water back up to the top of the waterfall.

With a new child in the family this pond could also be covered with strong enough screen designed well enough to keep children playing in the area safe from accidental drowning or other such dangers.

You mentioned that money is tight, so consider doing as much of the grunt work as you can. Maybe you even have some friends who are willing to help with either the labor or lending you any needed equipment and tools; along with giving you any of their tested and tried advice.

Check the local paper and lumber companies for seedlings, sometimes they will give them to you. International Paper gave me about a dozen longleaf pine seedlings last year.

How does cedrus deodara do there? It is fast growing.
David

I've had pretty good luck with mail order seedlings. Some companies sell in bulk and the ppl on this forum have TONS of experience ordering from them.

Musser Forests is the only one I've used. For example They sell 10 of them fast growing Hybrid Poplars for $32 plus shipping or 10 Eastern Red Cedars for $20 and shipping. Keep in mind these will be 2ft tall saplings you get, but they're easier to transplant than large trees and I feel they establish themselves better than pot-bound big box store trees.

Another choice is the clearance line at a big box store. Both Home Despot and Low'es here were almost giving away ($10 a piece or so!) six foot tall silver maples and other pot bound trees for the last month here in colder zone 6. They've stopped taking care of them it seems and are clearing the way for winter Christmas trees, but hey $10 is only two Jack & Cokes at the bar!

Here is a link that might be useful: Musser Forests

Oh yeah, plant some variety too. It adds to the year round interest level AND protects you incase any specialized tree eating bug comes to town. It would suck to have had only elms when Dutch Elm Disease came through.

P.S. they're not evergreens but your native Bald Cypress and the similar Dawn Redwood are two of my favorites.