Traffic noise distances

How far can you hear traffic?

My wife has an online knitting friend who used to rent an old farmhouse in the boonies and when we visited I noticed that I couldn't hear anything but the sounds of the fields. It was wonderful. So I was looking forward to that when we were going to move to "the country". Sadly, we failed to actualize that particular aspect. We live 1/2 mile south of a well-used state highway. I can almost always hear traffic from that road during the day. I get up at 0300 and the traffic at that time is quite sporadic so I also know what it sounds like when that road is silent. At those times, I can hear the interstate which is through about 3.5 miles of woods, as the crow files. The interstate is quiet -- a murmur even, but constant. Having had this experience, it seems like what I have is the most noise I could stand and I wish I'd bought somewhere more remote.

But how remote do you have to be in order to get the noise profile I'd like?

I think it depends. Highway noise, as you've noticed, can carry in strange ways, especially if that highway is near a grade, has a lot of heavy cargo or is a nice ride for motorcyclists.

Even remote-remote can be weird. I've mentioned elsewhere that during college I worked a summer at an FFA Fresh Air Fund camp waaaaaay out in the wilds of upstate NY (between a State Forest, a Wilderness, and a Wild Forest... the land of deer camps, bears and not much else).
A good half hour's drive to a paved road, an hour to a town where I could put my paycheck into the mail to my bank. I ran the horseback riding program and the first thing they told me when I arrived was "it takes an hour by helicopter to medivac anyone who gets hurt to the nearest hospital so don't take risks!" No pressure!

It was idyllic most of the time. But it was 40-odd miles from Fort Drum, and when they decided to play with explosives or do maneuvers with jets out at the fort, nobody could sleep and the horses would get upset. So maybe not just the highways but also the skyways are worth looking at.

Besides highway noise as Tereza suggests there are a lot of other factors.

Some could be road surface, such as gravel or pavement, heavy vehicle engines (big trucks), exhaust systems, even the high speed of traffic, all can create a continuous roar.

I am about 1/2 mile off a caliche (dirt) road and I never hear traffic.

When we lived in Dallas, I could hear my husbands truck when he was several blocks away (at night when it was quiet).

My grandparents bought a house on the main road.  Distance is difficult when one is a kid.  3.5 to 4 driveway width distance from heavy traffic

The developer made a sideways driveway parallel to the road for about 5 houses, then between that and the road, built a berm and massive hedge. You wouldn't know there was a main road there.

In Tokyo, I visited a garden.  Tokyo is LOUD.  But as soon as I entered the garden, all the noise stopped.  Completely. No traffic, no nothing.   It was like the scary feeling of being in the forest and suddenly the birds are quiet.

Where I live now, we are so far away from the road.  We could probably fit 6 suburban lots between us and the road.  I'm sitting here with the traffic so loud it's like sitting on the road.  Although, with trees, we've managed to make some quiet spots, it's still a work in progress. I suspect land is better at reducing traffic than trees.

Although, I heard there is a document out there that lists trees by species and traffic noise canceling rating.  I've never found it.

I once looked at a house about a half mile from the Interstate, and I too could hear the background noise as traffic went by. In that case it wasn't too bad. I suspect the more trees, shrubs, berms, and rock walls you have in the way... the less noise you will hear.