The more I think about Tim’s grocery line congestion example, the less useful I think it is as a comparison point for congestion tolling. The grocery market is simply too variegated to tell us much about consumer preferences. Although I do think it’s fair to say that, generally speaking, the fewer grocery-obtaining options a person has, the more likely they are to wait in a line, and not because there’s a correlation between between having few options and enjoyment of queuing. To the extent that we can draw lessons from the grocery example, I think they tell us that congestion pricing would improve user utility.

But the biggest flaw with the grocery analogy is this: checking out takes a non-trivial amount of time, whereas automobile toll-paying does not. So, if we have a toll lane with no item limit, the toll is of limited use to other customers, because they still have to wait for the person in front of them to check out, which can take a while. On the other hand, if you have a toll lane with an item limit, the item limit is doing most of the work in both speeding the flow of the line and deterring sufficient entry to the line to make it a true express lane. Because the toll adds little additional value, customers would be unlikely to pay to use the lane. They would be happy to use untolled, item-limited lanes, however, which are a universal feature of the modern grocery store.

So again, this is not a particularly apt comparison, but to the extent that it is, it suggests that congestion tolls on roads would probably enhance the user experience.