most of toronto has a squarish grid of main streets that originated as township roads and are spaced at 1¼-mile intervals (about 2 km). by running overnight buses along every second road in the grid, all parts of metro would be reached and 86% of the population would be within a 15-minute walk (taken as 1.25 km or ¾ mile). to avoid excessively long trips, some grid streets such as eglinton avenue would require two bus routes meeting end-to-end, but still just 15 routes would be needed to form the grid. the 506 carlton route had sufficient traffic to be retained in addition, for a total of 16 routes.