Just under the surface of my street that's being dug up I saw long pieces of wood--what are (were) those? ?

Question

Just under the surface of my street that's being dug up I saw long pieces of wood--what are (were) those? ?

Answer 1

Are you in an area where a seawall could be used?  Seattle's current seawall was made of wood.  Unfortunately it's rotting and nobody wants to pay for the replacement until the fate of the nearby highway is decided.

Answer 2

Probably planks that were used for road/sidewalk surfaces in the early part of the last century or so...

Answer 3

A lot of streets in older city's used to have trolley tracks.... When automobiles got popular they just pulled up the tracks and just paved over the old rail road ties (wood).....