Probably the single most common question that I’m asked is some variation of, “How much parking do I need?”

Sometimes it’s a question about a new development that needs to satisfy some archaic requirement: “How many spaces do I need to build, and is there any way to reduce that since they’re so unbelievably expensive to construct?” Other times, it’s related to what it might take to solve some existing parking problem: “How many spaces do we need to fix the mess on Southeast Division once and for all?”

My response, however the question might arrive, is always the same: “It depends. What’s the cost attached to that parking?”

See, the single most important thing to understand about parking is that, though it’s managed like a piece of civil infrastructure, parking behaves more like an economic resource. Like other commodities, parking is subject to the laws of supply-and-demand—this is essentially the plot of Shoup’s “The High Cost of Free Parking”—and so the less the end cost to the user, the greater the demand will be. The latest research has made us more confident in this assessment than ever.

Consider, then, how silly it is to manage parking exclusively as civil infrastructure. Often, we require new developments to construct enough new off-street parking to meet its peak demand load, just as we require them to, say, build a big enough pipe to meet its peak sewage flow. One might argue that  requiring enough parking to serve the peak expected demand makes sense (at least empirically; it makes less sense once you start to consider induced demand), and it certainly has an element of fairness to it. But most of the time, there’s an important if unspoken caveat: No user will ever be asked to pay for that parking.

When we ignore cost as a parameter, we ignore by extension the commodity-like aspects of parking. Of course, parking still behaveslike a commodity, so we’ve inadvertently created market conditions where oodles and oodles of free parking drive demand to irrational levels. Illustrated, it looks like this:

Of course, it’s important to consider the infrastructure ramifications of parking too; indeed, these have a drastic effect on all other aspects of the transportation system, and on the greater street culture and livability of a neighborhood. But it’s through studying parking through an economic lens that many of the most interesting management opportunities present themselves, and where the question of how much parking is needed starts to become rife with complexities and nuance…