You really need to grade-separate car traffic, public transit traffic, bicycles, and pedestrians. If you set your citywide story height to be 3.5m, you can put

You really need to grade-separate car traffic, public transit traffic, bicycles, and pedestrians. If you set your citywide story height to be 3.5m, you can put the automobile traffic at ground level, the pedestrian deck at +7m, and in the city center, also elevated bicycle lanes at +10.5m, and elevated trains at +14m. That allows for 1 or 2 stories of parking for each steel+concrete building, a double-height lobby level, with a bicycle-locker mezzanine, the possibility of double-height train stations built into buildings adjoining a mechanical floor, and "streets" that are narrower for walkers than for cars. I'd bet that the cost of putting a 7m deck over every road you pave, or at least an elevated walkway 2m wide, is easily saved by subtracting the sidewalk width from the ground-level road footprint, allowing greater building density. A 21.25m road footprint can fit 4 3.25m travel lanes, one 2.75m center turning lane, and two 2.75m right-turn/breakdown lanes. A 12m footprint can hold 2 3.25m travel lanes and 2 2.75m turn/breakdown lanes. Additionally, above the 7m vehicle clearance level, buildings can be cantilevered over the roadway, making the pedestrian "street" narrower than the road-for-cars below. In the US, the usual minimum acceptable neighborhood curb-to-curb street width is 8.5m, but then add sidewalks for a total footprint of 15.25m. Some neighborhoods allocate 18.25m for the right-of-way, with 12m for the road, then they add infuriating speed bumps. In Chicago[0], the major arterials are 30.5m wide, with at least 20% pedestrian width; minor arterials and collectors are 20m wide, with 33% for pedestrians. It's all based on the 66ft surveyor's chain. Stack the sidewalk over the street, and you give your city greater areal density and better use of available volume. [0] https://www.cityofchicago.org/dam/city/depts/cdot/StreetandSitePlanDesignStandards407.pdf https://www.cityofchicago.org/dam/city/depts/cdot/StreetandS...