Decisions based on space, time, and money
Where curb prices are based on demand, parking is more expensive near popular destinations and cheaper farther away. You can spend more money to park closer to your destination, or you can spend more time walking from a spot farther away. The optimal parking spot minimizes the sum of the driver’s money cost of parking and time cost of walking.
The value of saving time spent walking varies by trip and person. If you have plenty of time, you may park free a mile away. If you’re in a hurry, you may pay a high price to park right at your destination.
The value of saving time spent walking depends on the quality of the walk. At its best, walking is useful, safe, interesting, and enjoyable. In a walkable neighborhood, drivers can walk farther to save money and enjoy the stroll. Where the streets and sidewalks are dark, dirty, and unsafe, drivers will pay more to park closer to their destinations.
Market prices for curb parking serve as a buffer allowing late-arriving drivers to buy time when they need it most. Drivers who arrive late can spend more money to park closer to their destination and reduce walking time. Drivers who arrive early can park farther away and save money by spending more time walking. The option of paying more money to save time is a valuable form of travel insurance.
All models are wrong but some are useful
A market-based model cannot predict where all drivers will park, how long they will stay, or how much they will pay, but it is helpful in thinking about public policy.
A model of curb parking choice should include at least four variables: the price of parking at the meter, the number of people in the car, the length of time they want to park, and how fast they walk.
Drivers who buy time in the parking market will sort themselves out according to how long they want to stay, how many people are in the car, how fast they walk, how they value time, and many other factors that differ from one trip to another and that only individual drivers can know. Are they carrying heavy packages? Is it raining? To paraphrase Pascal, parking has reasons that reason will never know.
If parking prices increase as drivers approach their destinations, carpools, short-term parkers, slow walkers, and drivers with a high value of saving time will park closer to their destinations. Solo drivers, long-term parkers, fast walkers, and drivers with a low value of saving time will park farther away. This spontaneous, self-organizing pattern of parking will reduce the overall cost of time spent walking between parking spaces and destinations. The best individual choices will lead to a good collective outcome. If cities charge Goldilocks prices for curb parking, drivers will do the rest of the planning.
The length of time a driver parks for will vary much more than the other three variables. A high price per hour is not much of a problem if you park for a short time but it’s a big problem if you park for a long time. The number of people in the car and their walking speed will vary much less. For this reason, parking duration is the most important variable to consider when estimating how far drivers will walk to their final destinations.
The closer and more expensive spaces will turn over faster than the more distant and cheaper spaces. Convenient spaces will be available for quick trips and thus will increase the number of customers for local businesses.
To create a few open curb spaces everywhere, parking prices must vary by time and location. The peak prices might occur in commercial districts during weekdays and near entertainment venues during the evenings. As demand varies, parking prices at each location will rise or fall, and the local peaks will shift around like kittens fighting under a blanket. Popular places will have higher parking prices, but no one will have to search for parking like panning for gold.
Without any further action, demand-based prices for curb parking will make it hard for low-income residents to park in the highest-demand places. To mitigate this effect and ensure equity, cities can give low-income residents a discount on curb parking, just as they give discounts on electricity and water bills. High-income drivers will pay the market price for curb parking, and low-income drivers will get a subsidy. But if cities subsidize parking for low-income car owners, they should offer an equivalent subsidy (such as free transit passes) for other low-income residents who do not own a car. Subsidies should be for people, not just for drivers.