H/t to Barry Burden for sending along this article from the CapTimes in Madison, about a mock election intended to gauge the bottlenecks caused by having to check voter ID’s. The bottom line: if local officials staff their polling places as before, the wait times grow substantially. With some additional help and thoughtfulness in deploying them, the added wait time can drop by 3/4.
One thing not taken into account by this mock election (or at least the account of the mock election) is the timing of new voters joining the queue. The effect of heavy foot traffic tends to grow the length of queues in a highly non-linear fashion. Think about rush hour, where you can go from smooth traffic flow to gridlock with the addition of just a few more cars.