I would like to offer this solution to the problem of traffic being blocked by an overflow of drive-thru customers at Chick-fil-A.
The restaurant could charge a higher price for their drive-thru service during the hours when the overflow blocks State Street. It seems that the cost of products and services always determines the number of customers using them. The extra income generated could then be offered as coupons to customers, which could only be used at times when the traffic is usually minimal.
I think this would spread the traffic out to less during high volume times, to lower volume times, without negatively affecting the restaurant’s income and maybe even increasing it. This could be the restaurant’s way to control the traffic, just like a stop light does.