# Park and ride lot geometry

I don’t find park and ride lots attractive. I don’t want them in my neighborhood. I wish the land around park and ride lots were valuable. But let’s do some math.

In one acre, there are 43,560 square feet. It takes about 300 square feet to store a parked car (including lanes, etc.). This suggests you can store 145 parked cars per acre. That is similar to this result.

If every one of those parked cars carried 1 person, that is 145 transit boardings from that station in the morning (and 145 boardings elsewhere in the evening, assuming symmetry). That generates 290 daily transit trips.

In contrast, let’s say we had zero park and ride spaces. Let’s further assume that adjacent land uses have a 50% transit mode share for work trips and 0% for non-work trips. We would need 300 resident workers on that acre to have a similar number of transit trips generated. Since only half the population works, we are looking at 600 total persons on that acre of land. That is the equivalent of 384,000 persons per square mile. That is a lot of people.

Even if only workers lived there, and they had 100% transit mode share for work trips and another 2 non-work trips per day by transit, that is still 145 people per acre. That is the equivalent of 92,800 people per square mile. That is Manhattan like densities (actually higher). Of course not all of Manhattan is high-rise apartments, so that is not necessarily as high as the highest densities in Manhattan, but it is higher than the lowest densities in Manhattan.

Low, or even medium, density land use around the station will not enable as many transit users  as the park and ride lot.

I still don’t like park and ride lots.

Jarrett Walker has a different take