Hmmm, later the old walls of TYW time are replaced in many German towns by a Akzisemauer. Akzise = Steuer / Zoll ~ toll, tax.
The Berlin one was used to control the town border, some goods are not permited to enter without an aditional tax. No defensive wall, just a weak one. The only gate defence was the turnpike / tollgate. Keeping the Russians out in SYW for 5 minutes. 4 1/2 for and a few seconds to smash it.
But that's 18th century. In TYW times there was a real strong gate in the wall. And guards that checked for goods to be taxed. Sometimes there was an outer fence that had a tollgate.
Now did someone mention turnpikes? Apart from the fact they are 'roads' anything else make them special?
Indeed they are but it seems the origin of the word 'Turnpike' is from the spiked movable barricade or gate used to block streets in medieval and later times. The is an illustration of one in John Barret's the Civil War in the South West. I found it hard to find out anything more about them on t'net and I cannot find the picture on google