what is the average distance of a city block
City block Since the spacing of streets in grid plans varies so widely among cities, or even within cities, it is difficult to generalize about the size of a city block. However, as reference points, the standard square blocks of Portland, Houston, and Sacramento are 264 by 264 feet (80 m × 80 m), 330 by 330 feet (100 m × 100 m), and 410 by 410 feet (120 m × 120 m) respectively (to the street center line). Oblong blocks range considerably in width and length. The standard block in Manhattan is about 264 by 900 feet (80 m × 274 m); and in some U.S. cities standard blocks are as wide as 660 feet (200 m). The blocks in Calgary, Canada, are 330 by 560 feet (100 m × 170 m), while those in Edmonton, Canada are 197 by 560 feet (60 m × 171 m).[2] The blocks in central Melbourne, Australia, are 330 by 660 feet (100 m × 200 m), formed by splitting the square blocks in an original grid with a narrow street down the middle. In Chicago, Illinois and Minneapolis, Minnesota, a typical city block is 660 by 330 feet (200 m × 100 m) (w × h),[3][4] meaning that 16 east-west blocks or 8 north-south blocks measure one mile.
London Underground The system's first tunnels were built just below the surface, using the cut-and-cover method; later, smaller, roughly circular tunnels – which gave rise to its nickname, the Tube – were dug through at a deeper level.[8] The system has 270 stations and 250 miles (400 km) of track.[9] Despite its name, only 45% of the system is actually underground in tunnels, with much of the network in the outer environs of London being on the surface.[9] In addition, the Underground does not cover most southern parts of Greater London, with less than 10% of the stations located south of the River Thames.[9]