I have used SC4 Tool to extract the following textures.
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fi810.photobucket.com%2Falbums%2Fzz26%2FNijomi_Bucket%2FForum%2520Posts%2FTextureCompare.png&hash=f2d2d6527a88a8821817cd9740a1f8e434ad36ea)
I am right in assuming that applying them to 16m2 tiles in the BAT and measuring the widths is an accurate way of getting the dimensions of the sidewalks.
Well, that would be one way to do that. It would actually be a 256m2, because the size of the tile is 16m by 16m. And don't forget to switch texture correction on! The other way is measuring the width by the number of pixels the sidewalk takes up and divide that number by 8 (because 128/16 = 8). Either way would give you the same result.
Best,
Maarten