H/t to @urbandata for tweeting this graphic that shows how different transportation modes use road space. On a typical lane of road in a city, cars in mixed traffic can carry 2,000 people per hour, where bicycles can carry 14,000 and street rail can carry 22,000. That’s quite a scale.(see a larger image of that graphic here)The low carrying capacity of a personal car may be fine in a low-density environment, but dense urban centers cannot be effectively served by cars. The chart above shows carrying capacity, but also consider the amount of road and parking infrastructure needed by a high volume of cars – when you couple that need with capacity, it’s clear that cars are a spatially inefficient form of transportation for city centers.And yet we bend over backwards to receive and store tons of them to the middle of Atlanta. Here’s a photo of Downtown that I’ve edited to show where the streets and parking facilities are. The buildings that humans actually use are separated by all of these car facilities – and when the pattern gets repeated, those separations create a terrain that’s more challenging to pedestrians than a downtown should be. Here’s a photo of Midtown Atlanta near interstate 75/85. Look at the “dead” space (meaning that its unusable by people outside of cars) that’s created by these lanes and parking spaces. To get from the area in the top, right of this photo to the bottom – I couldn’t blame anyone for hopping in a car instead of walking. This situation that’s challenging for pedestrians just serves to enforce the use of these spatially-inefficient cars in the city center. Midtown in general has seen great strides in the reduction of surface parking lots. It is definitely one of the more walkable parts of the city. But with fewer cars on the road (and the conversion of multi-lane, one-way streets in Midtown that cary them), it could realize its full potential for healthy density.Even when we add street rail to the city center by way of the Atlanta Streetcar, we’re not completely out of the woods. This photo shows a section of the streetcar line that’s hindered by an interstate overpass and entrance/exit ramps. How many streetcar riders will exit the train and want to walk past these entrance and exit ramps for the interstate? Could you blame someone for deciding to drive to a destination near this overpass instead? The bulk of the streetcar line is very nice to walk around, by the way. And this overpass is being put to good use by housing the maintenance facility underneath. But the entrance and exit ramps – serving the large number of cars in the area – are a problem here. The natural progression of urban density is being stunted in Atlanta’s core by the presence of this level of car traffic and infrastructure. We’re left with a half-assed kind of density, thanks to detached parking decks and surface lots and land-hogging interstate infrastructure that are all taking up spaces that could be used by human habitats.I had a daydream recently that involved closing off all the interstate exit ramps in the center of the city to cars and only allowing emergency vehicles, delivery trucks, buses and carpool riders to use them. It’s an extreme idea, but I can’t help but dream about it – and basically anything that would reduce the number of cars we bring into the city center. And I want to make sure that “reduce” is clear; I am not a proponent of car free cities. I just want a better balance that prevents cars from being so dominant. In that balance, we can create a more healthy kind of density.(h/t Tyler Blazer for constructive criticism on the post; edits were made)