The Surveyor allows the player to build a fence between two houses on the same street. To build a fence, choose any available, white-dotted space and draw a line on it.
Permanent fences are present on both sides of each street. Fences determine the boundaries of housing estates. A completed housing estate is a row of 1 to 6 neighboring houses, all numbered (no blank spaces between them) and built between two fences. Completed housing estates are necessary to fulfill City Plans and may be split further, as long as they have not previously fulfilled a City Plan.
The architect has written a 5 on the third house of the second street in order to start a 3-house estate.
Then they built a fence between the first and the second house of the first street, therefore splitting a 3-House estate into 1-house and 2-house estates.