[jyl]

I could see the street next to me becoming noisier in the next 5, 10, 15, etc years.

It is not particularly noisy now, but the city is growing and there is room to expand from 2 lanes to 4 - they'd have to eliminate bike lanes and piss off an influential neighborhood, but you never know. . .

So, I was thinking about planting some trees as a sound and visual block now, in case they are needed in 10 years.

I could plant them along the sidewalk grass strip, they'd have to go between and in the shade of a pair of huge, old existing trees. Or I could plant them at the edge of my side yard, which is elevated appx 6' above street level, but also shaded.

Question - how effective are trees, to reduce car noise? What types of trees are most effective? Cypress? Some sort of evergreen? Are deciduous trees are less effective (simply because they're leafless part of the year).

In case it is not obvious, I know zip about trees . . .