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What Percentage of Parking Spots Would It Take to Build a Bike Network?

A protected bike lane carved from parking in San Francisco.
If we removed parking from major streets to create protected bike lanes, what percentage of the city's parking would that represent?

To find out, I tried to think about how many on-street parking spots there might be in Providence. This turned out to be kind of a hard thing to do. Providence Department of Public Works lists 370 miles of roadway in its care, which presumably does not include streets under RIDOT's watch (RIDOT controls fewer streets than I thought, but still a substantial amount: N. Main, the West Side's Westminster, Elmwood, Allens, and Hartford. I thought they controlled Broad Street, Waterman, and Angell, among others, but I was apparently wrong).

In any case, let's round up the list and say that there are 400 miles of streets in Providence, most of which have double-sided parking (so, we're up to 800 miles). We can probably assume that upwards of 1/3 to 1/2 of that space ist taken up by things like driveways (which of course offer their own parking), crosswalks, and fire hydrants. 

It's hard to estimate what the average block length is in Providence, since the grid is pretty irregular, but when I clicked on blocks in a kind of random fashion throughout the city, it looked like they ranged between 0.1 of a mile and 0.2 of a mile. So let's say 0.15 to be safe. If most streets are 30-40 feet in width, and you've got a crossing every 0.15 mile, that's going to cut into your parking spots a tad too.

So let's say that rather than 800 miles of end-to-end cars, we've got something closer to 400 flat, once all those obstructions have been taken out.

Now, how many miles of protected bike lanes would we need to form a superb network throughout the city?

Two years ago, a temporary protected bike lane went in on
1.7 miles of Broadway in Providence. It required removing
just one side of the street's parking. When will we make
it permanent?
I think if we got up to 50 miles, that would be great. Just estimating off of the East Side and extrapolating-- N. Main, Hope, Blackstone, Waterman, and Angell, and Wickenden-- that's like 10 miles right there). Multiply that to include a variety of neighborhoods, and you're looking at around 50 miles.

50 out of 400*. But, now, keep in mind that on some of these streets parking wouldn't be removed (Blackstone, for instance, could get protected bike lanes without removing parking). On most of these streets, you could remove just one side of the parking, and leave the other side. So maybe we're looking at 20-25 miles of parking, out of 400.

So 1 on-street parking spot out of 16 32 could be removed, and from that we could get a bike network that was unmatched in any place outside of Denmark or the Netherlands.

Even if you drive everywhere, 1 out of 16  out of 32 doesn't sound so bad (and truthfully, we could start by doing a fraction of that-- going for 20 miles of protected bike lanes would be a start towards the goal of 50, and would get a lot of new cyclists on the road). But take a look at these aerial views of neighborhoods to see how little parking is truly taken up (It helps to enlarge these photos and really look-- the parking's pretty empty).

Hope Street

Note how empty the parking is even at the CVS parking lot, off-street. Also, keep in mind that almost every one of these houses has a driveway that can hold two or more cars, which people could use by signing up for the Park with Spotter App.

I chose the busiest area of parking for Hope Street, around the merchant area. However, I think everyone (including the merchants) will agree that the parking is even emptier in between this area and Brown, where there's often only a parked car every several hundred feet or so).


Off Street Parking is Pretty Empty

Behind the Biltmore. I've seen it emptier than this. Yay for building more garages!
Now Let's Add Parking Back In

So we've been working with a 1 to 16 32 ratio-- about 6% 3% of on-street parking-- and leaving all off-street parking alone. We've also shown using Google Maps that parking throughout the city is fairly empty.

But what if we used bike infrastructure to add parking back in?

Creating neighborhood greenways could allow more parking on some streets.

This pedestrian plaza in the Graduate Hospital District in Philadelphia removed some parking spots, but added them back in another place. Removing some parking for protected bike lanes could also involve adding some elsewhere.
A lot of neighborhood streets, like Elmgrove, have too much room, allowing speeding. What if we put large bump-outs in with trees and greenery, and allowed people to have angled parking next to those green areas. As you can see, there's already no shortage of parking, but angled parking adds parking spaces.

Elmgrove has no shortage of parking, and lots of space. But could we add parking spots here by angling parking, and using
bump-outs to narrow the travel space? This could deal with neighborhood speeding issues.
Adding parking is not something I love. It's not a proposal to please me. But if we could add parking spots by changing their orientation, perhaps we could also slow cars. I think streets like Elmgrove would do well with diagonal diverters and periodic roundabouts added to slow cars as well, like with bike boulevards.

Changing Demand

So we should remove about 6% of parking, add some new parking along neighborhood streets, make parking spaces available on driveways using the Park with Spotter App. What else comes into play?

Getting people to bike will also reduce the number of drivers, and reduce the amount of storage space needed, thus opening up more parking.

A single parking space can comfortably hold ten bikes. That means for every ten people you get on a bike, you get 11 9 parking spaces-- one for each of the cars not on the road, and another bonus one minus the spot for the bike corral (It also should be noted that bike corrals can get really intense, like the ones in the Netherlands, which are two-tiered and can hold even more bikes).

When you start to look the math, removing some parking to add protected bike lanes adds up for your business. It means that you're ultimately adding the number of people who can shop at your store. You're making parking available for drivers who decide not to bike. It's an investment towards expanded business.

*So, the more I thought about this after publishing this post, the less it seems relevant to me whether all the space on the street is parking spaces or not. For example, if you'd credit the parking spaces with the areas lost to driveways and fire hydrants and so on, you have to do the same to the protected bike lanes (since an equal ratio of space is going to be taken up by those things as well). So Maybe it's more like 50 out of 800. And in that case we're looking at around 3% of the parking on-street spaces, to create a massive bike network.

You can argue about this in the comments section if you want.

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