on a block of downtown san francisco, there are two block-long lines labelled 'address interpolation'. there aren't many nodes along this block, but the ones that exist mostly have explicit addresses assigned.
these were created 14 years ago (potlatch 0.10f). what do they do, are they valuable to renderers or to the map itself?
As others have said, these are lines to make it possible to guess where a specific house number might be based on the start and end numbers of the line.
I usually recommend against deleting this kind of thing unless you can confirm that locals don't care or if it's not present in surrounding blocks.